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kernel/futex.c
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/* * Fast Userspace Mutexes (which I call "Futexes!"). * (C) Rusty Russell, IBM 2002 * * Generalized futexes, futex requeueing, misc fixes by Ingo Molnar * (C) Copyright 2003 Red Hat Inc, All Rights Reserved * * Removed page pinning, fix privately mapped COW pages and other cleanups * (C) Copyright 2003, 2004 Jamie Lokier * |
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* Robust futex support started by Ingo Molnar * (C) Copyright 2006 Red Hat Inc, All Rights Reserved * Thanks to Thomas Gleixner for suggestions, analysis and fixes. * |
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* PI-futex support started by Ingo Molnar and Thomas Gleixner * Copyright (C) 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> * Copyright (C) 2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com> * |
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* PRIVATE futexes by Eric Dumazet * Copyright (C) 2007 Eric Dumazet <dada1@cosmosbay.com> * |
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* Requeue-PI support by Darren Hart <dvhltc@us.ibm.com> * Copyright (C) IBM Corporation, 2009 * Thanks to Thomas Gleixner for conceptual design and careful reviews. * |
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* Thanks to Ben LaHaise for yelling "hashed waitqueues" loudly * enough at me, Linus for the original (flawed) idea, Matthew * Kirkwood for proof-of-concept implementation. * * "The futexes are also cursed." * "But they come in a choice of three flavours!" * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ #include <linux/slab.h> #include <linux/poll.h> #include <linux/fs.h> #include <linux/file.h> #include <linux/jhash.h> #include <linux/init.h> #include <linux/futex.h> #include <linux/mount.h> #include <linux/pagemap.h> #include <linux/syscalls.h> |
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#include <linux/signal.h> |
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#include <linux/export.h> |
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#include <linux/magic.h> |
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#include <linux/pid.h> #include <linux/nsproxy.h> |
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#include <linux/ptrace.h> |
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#include <linux/sched/rt.h> |
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#include <linux/sched/wake_q.h> |
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#include <linux/sched/mm.h> |
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#include <linux/hugetlb.h> |
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#include <linux/freezer.h> |
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#include <linux/bootmem.h> |
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#include <linux/fault-inject.h> |
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#include <asm/futex.h> |
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#include "locking/rtmutex_common.h" |
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/* |
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* READ this before attempting to hack on futexes! * * Basic futex operation and ordering guarantees * ============================================= |
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* * The waiter reads the futex value in user space and calls * futex_wait(). This function computes the hash bucket and acquires * the hash bucket lock. After that it reads the futex user space value |
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* again and verifies that the data has not changed. If it has not changed * it enqueues itself into the hash bucket, releases the hash bucket lock * and schedules. |
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* * The waker side modifies the user space value of the futex and calls |
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* futex_wake(). This function computes the hash bucket and acquires the * hash bucket lock. Then it looks for waiters on that futex in the hash * bucket and wakes them. |
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* |
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* In futex wake up scenarios where no tasks are blocked on a futex, taking * the hb spinlock can be avoided and simply return. In order for this * optimization to work, ordering guarantees must exist so that the waiter * being added to the list is acknowledged when the list is concurrently being * checked by the waker, avoiding scenarios like the following: |
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* * CPU 0 CPU 1 * val = *futex; * sys_futex(WAIT, futex, val); * futex_wait(futex, val); * uval = *futex; * *futex = newval; * sys_futex(WAKE, futex); * futex_wake(futex); * if (queue_empty()) * return; * if (uval == val) * lock(hash_bucket(futex)); * queue(); * unlock(hash_bucket(futex)); * schedule(); * * This would cause the waiter on CPU 0 to wait forever because it * missed the transition of the user space value from val to newval * and the waker did not find the waiter in the hash bucket queue. |
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* |
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* The correct serialization ensures that a waiter either observes * the changed user space value before blocking or is woken by a * concurrent waker: * * CPU 0 CPU 1 |
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* val = *futex; * sys_futex(WAIT, futex, val); * futex_wait(futex, val); |
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* |
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* waiters++; (a) |
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* smp_mb(); (A) <-- paired with -. * | * lock(hash_bucket(futex)); | * | * uval = *futex; | * | *futex = newval; * | sys_futex(WAKE, futex); * | futex_wake(futex); * | * `--------> smp_mb(); (B) |
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* if (uval == val) |
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* queue(); |
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* unlock(hash_bucket(futex)); |
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* schedule(); if (waiters) * lock(hash_bucket(futex)); |
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* else wake_waiters(futex); * waiters--; (b) unlock(hash_bucket(futex)); |
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* |
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* Where (A) orders the waiters increment and the futex value read through * atomic operations (see hb_waiters_inc) and where (B) orders the write |
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* to futex and the waiters read -- this is done by the barriers for both * shared and private futexes in get_futex_key_refs(). |
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* * This yields the following case (where X:=waiters, Y:=futex): * * X = Y = 0 * * w[X]=1 w[Y]=1 * MB MB * r[Y]=y r[X]=x * * Which guarantees that x==0 && y==0 is impossible; which translates back into * the guarantee that we cannot both miss the futex variable change and the * enqueue. |
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* * Note that a new waiter is accounted for in (a) even when it is possible that * the wait call can return error, in which case we backtrack from it in (b). * Refer to the comment in queue_lock(). * * Similarly, in order to account for waiters being requeued on another * address we always increment the waiters for the destination bucket before * acquiring the lock. It then decrements them again after releasing it - * the code that actually moves the futex(es) between hash buckets (requeue_futex) * will do the additional required waiter count housekeeping. This is done for * double_lock_hb() and double_unlock_hb(), respectively. |
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*/ |
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#ifndef CONFIG_HAVE_FUTEX_CMPXCHG |
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int __read_mostly futex_cmpxchg_enabled; |
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#endif |
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/* |
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* Futex flags used to encode options to functions and preserve them across * restarts. */ |
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#ifdef CONFIG_MMU # define FLAGS_SHARED 0x01 #else /* * NOMMU does not have per process address space. Let the compiler optimize * code away. */ # define FLAGS_SHARED 0x00 #endif |
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#define FLAGS_CLOCKRT 0x02 #define FLAGS_HAS_TIMEOUT 0x04 /* |
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* Priority Inheritance state: */ struct futex_pi_state { /* * list of 'owned' pi_state instances - these have to be * cleaned up in do_exit() if the task exits prematurely: */ struct list_head list; /* * The PI object: */ struct rt_mutex pi_mutex; struct task_struct *owner; atomic_t refcount; union futex_key key; |
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} __randomize_layout; |
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/** * struct futex_q - The hashed futex queue entry, one per waiting task |
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* @list: priority-sorted list of tasks waiting on this futex |
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* @task: the task waiting on the futex * @lock_ptr: the hash bucket lock * @key: the key the futex is hashed on * @pi_state: optional priority inheritance state * @rt_waiter: rt_waiter storage for use with requeue_pi * @requeue_pi_key: the requeue_pi target futex key * @bitset: bitset for the optional bitmasked wakeup * |
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* We use this hashed waitqueue, instead of a normal wait_queue_entry_t, so |
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* we can wake only the relevant ones (hashed queues may be shared). * * A futex_q has a woken state, just like tasks have TASK_RUNNING. |
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* It is considered woken when plist_node_empty(&q->list) || q->lock_ptr == 0. |
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* The order of wakeup is always to make the first condition true, then |
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* the second. * * PI futexes are typically woken before they are removed from the hash list via * the rt_mutex code. See unqueue_me_pi(). |
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*/ struct futex_q { |
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struct plist_node list; |
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|
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struct task_struct *task; |
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spinlock_t *lock_ptr; |
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union futex_key key; |
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struct futex_pi_state *pi_state; |
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struct rt_mutex_waiter *rt_waiter; |
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union futex_key *requeue_pi_key; |
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u32 bitset; |
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} __randomize_layout; |
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static const struct futex_q futex_q_init = { /* list gets initialized in queue_me()*/ .key = FUTEX_KEY_INIT, .bitset = FUTEX_BITSET_MATCH_ANY }; |
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/* |
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* Hash buckets are shared by all the futex_keys that hash to the same * location. Each key may have multiple futex_q structures, one for each task * waiting on a futex. |
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*/ struct futex_hash_bucket { |
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atomic_t waiters; |
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spinlock_t lock; struct plist_head chain; |
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} ____cacheline_aligned_in_smp; |
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/* * The base of the bucket array and its size are always used together * (after initialization only in hash_futex()), so ensure that they * reside in the same cacheline. */ static struct { struct futex_hash_bucket *queues; unsigned long hashsize; } __futex_data __read_mostly __aligned(2*sizeof(long)); #define futex_queues (__futex_data.queues) #define futex_hashsize (__futex_data.hashsize) |
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/* * Fault injections for futexes. */ #ifdef CONFIG_FAIL_FUTEX static struct { struct fault_attr attr; |
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bool ignore_private; |
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} fail_futex = { .attr = FAULT_ATTR_INITIALIZER, |
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.ignore_private = false, |
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}; static int __init setup_fail_futex(char *str) { return setup_fault_attr(&fail_futex.attr, str); } __setup("fail_futex=", setup_fail_futex); |
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static bool should_fail_futex(bool fshared) |
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{ if (fail_futex.ignore_private && !fshared) return false; return should_fail(&fail_futex.attr, 1); } #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS static int __init fail_futex_debugfs(void) { umode_t mode = S_IFREG | S_IRUSR | S_IWUSR; struct dentry *dir; dir = fault_create_debugfs_attr("fail_futex", NULL, &fail_futex.attr); if (IS_ERR(dir)) return PTR_ERR(dir); if (!debugfs_create_bool("ignore-private", mode, dir, &fail_futex.ignore_private)) { debugfs_remove_recursive(dir); return -ENOMEM; } return 0; } late_initcall(fail_futex_debugfs); #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */ #else static inline bool should_fail_futex(bool fshared) { return false; } #endif /* CONFIG_FAIL_FUTEX */ |
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static inline void futex_get_mm(union futex_key *key) { |
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mmgrab(key->private.mm); |
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/* * Ensure futex_get_mm() implies a full barrier such that * get_futex_key() implies a full barrier. This is relied upon |
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* as smp_mb(); (B), see the ordering comment above. |
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*/ |
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smp_mb__after_atomic(); |
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} |
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/* * Reflects a new waiter being added to the waitqueue. */ static inline void hb_waiters_inc(struct futex_hash_bucket *hb) |
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{ #ifdef CONFIG_SMP |
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atomic_inc(&hb->waiters); |
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/* |
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* Full barrier (A), see the ordering comment above. |
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*/ |
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smp_mb__after_atomic(); |
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#endif } /* * Reflects a waiter being removed from the waitqueue by wakeup * paths. */ static inline void hb_waiters_dec(struct futex_hash_bucket *hb) { #ifdef CONFIG_SMP atomic_dec(&hb->waiters); #endif } |
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static inline int hb_waiters_pending(struct futex_hash_bucket *hb) { #ifdef CONFIG_SMP return atomic_read(&hb->waiters); |
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#else |
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return 1; |
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#endif } |
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/** * hash_futex - Return the hash bucket in the global hash * @key: Pointer to the futex key for which the hash is calculated * * We hash on the keys returned from get_futex_key (see below) and return the * corresponding hash bucket in the global hash. |
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*/ static struct futex_hash_bucket *hash_futex(union futex_key *key) { u32 hash = jhash2((u32*)&key->both.word, (sizeof(key->both.word)+sizeof(key->both.ptr))/4, key->both.offset); |
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return &futex_queues[hash & (futex_hashsize - 1)]; |
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} |
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/** * match_futex - Check whether two futex keys are equal * @key1: Pointer to key1 * @key2: Pointer to key2 * |
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* Return 1 if two futex_keys are equal, 0 otherwise. */ static inline int match_futex(union futex_key *key1, union futex_key *key2) { |
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return (key1 && key2 && key1->both.word == key2->both.word |
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&& key1->both.ptr == key2->both.ptr && key1->both.offset == key2->both.offset); } |
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/* * Take a reference to the resource addressed by a key. * Can be called while holding spinlocks. * */ static void get_futex_key_refs(union futex_key *key) { if (!key->both.ptr) return; |
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/* * On MMU less systems futexes are always "private" as there is no per * process address space. We need the smp wmb nevertheless - yes, * arch/blackfin has MMU less SMP ... */ if (!IS_ENABLED(CONFIG_MMU)) { smp_mb(); /* explicit smp_mb(); (B) */ return; } |
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switch (key->both.offset & (FUT_OFF_INODE|FUT_OFF_MMSHARED)) { case FUT_OFF_INODE: |
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ihold(key->shared.inode); /* implies smp_mb(); (B) */ |
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break; case FUT_OFF_MMSHARED: |
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futex_get_mm(key); /* implies smp_mb(); (B) */ |
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break; |
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default: |
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/* * Private futexes do not hold reference on an inode or * mm, therefore the only purpose of calling get_futex_key_refs * is because we need the barrier for the lockless waiter check. */ |
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smp_mb(); /* explicit smp_mb(); (B) */ |
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} } /* * Drop a reference to the resource addressed by a key. |
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* The hash bucket spinlock must not be held. This is * a no-op for private futexes, see comment in the get * counterpart. |
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*/ static void drop_futex_key_refs(union futex_key *key) { |
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if (!key->both.ptr) { /* If we're here then we tried to put a key we failed to get */ WARN_ON_ONCE(1); |
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return; |
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} |
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if (!IS_ENABLED(CONFIG_MMU)) return; |
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switch (key->both.offset & (FUT_OFF_INODE|FUT_OFF_MMSHARED)) { case FUT_OFF_INODE: iput(key->shared.inode); break; case FUT_OFF_MMSHARED: mmdrop(key->private.mm); break; } } |
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/** |
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* get_futex_key() - Get parameters which are the keys for a futex * @uaddr: virtual address of the futex * @fshared: 0 for a PROCESS_PRIVATE futex, 1 for PROCESS_SHARED * @key: address where result is stored. |
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* @rw: mapping needs to be read/write (values: VERIFY_READ, * VERIFY_WRITE) |
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* |
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* Return: a negative error code or 0 * |
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* The key words are stored in @key on success. |
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* |
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* For shared mappings, it's (page->index, file_inode(vma->vm_file), |
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* offset_within_page). For private mappings, it's (uaddr, current->mm). * We can usually work out the index without swapping in the page. * |
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* lock_page() might sleep, the caller should not hold a spinlock. |
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*/ |
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486 |
static int |
9ea71503a futex: Fix regres... |
487 |
get_futex_key(u32 __user *uaddr, int fshared, union futex_key *key, int rw) |
1da177e4c Linux-2.6.12-rc2 |
488 |
{ |
e2970f2fb [PATCH] pi-futex:... |
489 |
unsigned long address = (unsigned long)uaddr; |
1da177e4c Linux-2.6.12-rc2 |
490 |
struct mm_struct *mm = current->mm; |
077fa7aed futex: Calculate ... |
491 |
struct page *page, *tail; |
14d27abd1 futex, thp: remov... |
492 |
struct address_space *mapping; |
9ea71503a futex: Fix regres... |
493 |
int err, ro = 0; |
1da177e4c Linux-2.6.12-rc2 |
494 495 496 497 |
/* * The futex address must be "naturally" aligned. */ |
e2970f2fb [PATCH] pi-futex:... |
498 |
key->both.offset = address % PAGE_SIZE; |
34f01cc1f FUTEX: new PRIVAT... |
499 |
if (unlikely((address % sizeof(u32)) != 0)) |
1da177e4c Linux-2.6.12-rc2 |
500 |
return -EINVAL; |
e2970f2fb [PATCH] pi-futex:... |
501 |
address -= key->both.offset; |
1da177e4c Linux-2.6.12-rc2 |
502 |
|
5cdec2d83 futex: move user ... |
503 504 |
if (unlikely(!access_ok(rw, uaddr, sizeof(u32)))) return -EFAULT; |
ab51fbab3 futex: Fault/erro... |
505 506 |
if (unlikely(should_fail_futex(fshared))) return -EFAULT; |
1da177e4c Linux-2.6.12-rc2 |
507 |
/* |
34f01cc1f FUTEX: new PRIVAT... |
508 509 510 511 512 513 514 |
* PROCESS_PRIVATE futexes are fast. * As the mm cannot disappear under us and the 'key' only needs * virtual address, we dont even have to find the underlying vma. * Note : We do have to check 'uaddr' is a valid user address, * but access_ok() should be faster than find_vma() */ if (!fshared) { |
34f01cc1f FUTEX: new PRIVAT... |
515 516 |
key->private.mm = mm; key->private.address = address; |
8ad7b378d futex: Rename bar... |
517 |
get_futex_key_refs(key); /* implies smp_mb(); (B) */ |
34f01cc1f FUTEX: new PRIVAT... |
518 519 |
return 0; } |
1da177e4c Linux-2.6.12-rc2 |
520 |
|
38d47c1b7 futex: rely on ge... |
521 |
again: |
ab51fbab3 futex: Fault/erro... |
522 523 524 |
/* Ignore any VERIFY_READ mapping (futex common case) */ if (unlikely(should_fail_futex(fshared))) return -EFAULT; |
7485d0d37 futexes: Remove r... |
525 |
err = get_user_pages_fast(address, 1, 1, &page); |
9ea71503a futex: Fix regres... |
526 527 528 529 530 531 532 533 |
/* * If write access is not required (eg. FUTEX_WAIT), try * and get read-only access. */ if (err == -EFAULT && rw == VERIFY_READ) { err = get_user_pages_fast(address, 1, 0, &page); ro = 1; } |
38d47c1b7 futex: rely on ge... |
534 535 |
if (err < 0) return err; |
9ea71503a futex: Fix regres... |
536 537 |
else err = 0; |
38d47c1b7 futex: rely on ge... |
538 |
|
65d8fc777 futex: Remove req... |
539 540 541 542 543 544 545 546 547 548 |
/* * The treatment of mapping from this point on is critical. The page * lock protects many things but in this context the page lock * stabilizes mapping, prevents inode freeing in the shared * file-backed region case and guards against movement to swap cache. * * Strictly speaking the page lock is not needed in all cases being * considered here and page lock forces unnecessarily serialization * From this point on, mapping will be re-verified if necessary and * page lock will be acquired only if it is unavoidable |
077fa7aed futex: Calculate ... |
549 550 551 552 553 554 555 |
* * Mapping checks require the head page for any compound page so the * head page and mapping is looked up now. For anonymous pages, it * does not matter if the page splits in the future as the key is * based on the address. For filesystem-backed pages, the tail is * required as the index of the page determines the key. For * base pages, there is no tail page and tail == page. |
65d8fc777 futex: Remove req... |
556 |
*/ |
077fa7aed futex: Calculate ... |
557 |
tail = page; |
65d8fc777 futex: Remove req... |
558 559 |
page = compound_head(page); mapping = READ_ONCE(page->mapping); |
e6780f724 futex: Fix uninte... |
560 |
/* |
14d27abd1 futex, thp: remov... |
561 |
* If page->mapping is NULL, then it cannot be a PageAnon |
e6780f724 futex: Fix uninte... |
562 563 564 565 566 567 568 569 570 571 572 |
* page; but it might be the ZERO_PAGE or in the gate area or * in a special mapping (all cases which we are happy to fail); * or it may have been a good file page when get_user_pages_fast * found it, but truncated or holepunched or subjected to * invalidate_complete_page2 before we got the page lock (also * cases which we are happy to fail). And we hold a reference, * so refcount care in invalidate_complete_page's remove_mapping * prevents drop_caches from setting mapping to NULL beneath us. * * The case we do have to guard against is when memory pressure made * shmem_writepage move it from filecache to swapcache beneath us: |
14d27abd1 futex, thp: remov... |
573 |
* an unlikely race, but we do need to retry for page->mapping. |
e6780f724 futex: Fix uninte... |
574 |
*/ |
65d8fc777 futex: Remove req... |
575 576 577 578 579 580 581 582 583 584 |
if (unlikely(!mapping)) { int shmem_swizzled; /* * Page lock is required to identify which special case above * applies. If this is really a shmem page then the page lock * will prevent unexpected transitions. */ lock_page(page); shmem_swizzled = PageSwapCache(page) || page->mapping; |
14d27abd1 futex, thp: remov... |
585 586 |
unlock_page(page); put_page(page); |
65d8fc777 futex: Remove req... |
587 |
|
e6780f724 futex: Fix uninte... |
588 589 |
if (shmem_swizzled) goto again; |
65d8fc777 futex: Remove req... |
590 |
|
e6780f724 futex: Fix uninte... |
591 |
return -EFAULT; |
38d47c1b7 futex: rely on ge... |
592 |
} |
1da177e4c Linux-2.6.12-rc2 |
593 594 595 596 |
/* * Private mappings are handled in a simple way. * |
65d8fc777 futex: Remove req... |
597 598 599 |
* If the futex key is stored on an anonymous page, then the associated * object is the mm which is implicitly pinned by the calling process. * |
1da177e4c Linux-2.6.12-rc2 |
600 601 |
* NOTE: When userspace waits on a MAP_SHARED mapping, even if * it's a read-only handle, it's expected that futexes attach to |
38d47c1b7 futex: rely on ge... |
602 |
* the object not the particular process. |
1da177e4c Linux-2.6.12-rc2 |
603 |
*/ |
14d27abd1 futex, thp: remov... |
604 |
if (PageAnon(page)) { |
9ea71503a futex: Fix regres... |
605 606 607 608 |
/* * A RO anonymous page will never change and thus doesn't make * sense for futex operations. */ |
ab51fbab3 futex: Fault/erro... |
609 |
if (unlikely(should_fail_futex(fshared)) || ro) { |
9ea71503a futex: Fix regres... |
610 611 612 |
err = -EFAULT; goto out; } |
38d47c1b7 futex: rely on ge... |
613 |
key->both.offset |= FUT_OFF_MMSHARED; /* ref taken on mm */ |
1da177e4c Linux-2.6.12-rc2 |
614 |
key->private.mm = mm; |
e2970f2fb [PATCH] pi-futex:... |
615 |
key->private.address = address; |
65d8fc777 futex: Remove req... |
616 617 |
get_futex_key_refs(key); /* implies smp_mb(); (B) */ |
38d47c1b7 futex: rely on ge... |
618 |
} else { |
65d8fc777 futex: Remove req... |
619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 |
struct inode *inode; /* * The associated futex object in this case is the inode and * the page->mapping must be traversed. Ordinarily this should * be stabilised under page lock but it's not strictly * necessary in this case as we just want to pin the inode, not * update the radix tree or anything like that. * * The RCU read lock is taken as the inode is finally freed * under RCU. If the mapping still matches expectations then the * mapping->host can be safely accessed as being a valid inode. */ rcu_read_lock(); if (READ_ONCE(page->mapping) != mapping) { rcu_read_unlock(); put_page(page); goto again; } inode = READ_ONCE(mapping->host); if (!inode) { rcu_read_unlock(); put_page(page); goto again; } /* * Take a reference unless it is about to be freed. Previously * this reference was taken by ihold under the page lock * pinning the inode in place so i_lock was unnecessary. The * only way for this check to fail is if the inode was |
48fb6f4db futex: Remove unn... |
654 655 |
* truncated in parallel which is almost certainly an * application bug. In such a case, just retry. |
65d8fc777 futex: Remove req... |
656 657 658 659 660 |
* * We are not calling into get_futex_key_refs() in file-backed * cases, therefore a successful atomic_inc return below will * guarantee that get_futex_key() will still imply smp_mb(); (B). */ |
48fb6f4db futex: Remove unn... |
661 |
if (!atomic_inc_not_zero(&inode->i_count)) { |
65d8fc777 futex: Remove req... |
662 663 664 665 666 667 668 669 670 671 672 673 674 675 |
rcu_read_unlock(); put_page(page); goto again; } /* Should be impossible but lets be paranoid for now */ if (WARN_ON_ONCE(inode->i_mapping != mapping)) { err = -EFAULT; rcu_read_unlock(); iput(inode); goto out; } |
38d47c1b7 futex: rely on ge... |
676 |
key->both.offset |= FUT_OFF_INODE; /* inode-based key */ |
65d8fc777 futex: Remove req... |
677 |
key->shared.inode = inode; |
077fa7aed futex: Calculate ... |
678 |
key->shared.pgoff = basepage_index(tail); |
65d8fc777 futex: Remove req... |
679 |
rcu_read_unlock(); |
1da177e4c Linux-2.6.12-rc2 |
680 |
} |
9ea71503a futex: Fix regres... |
681 |
out: |
14d27abd1 futex, thp: remov... |
682 |
put_page(page); |
9ea71503a futex: Fix regres... |
683 |
return err; |
1da177e4c Linux-2.6.12-rc2 |
684 |
} |
ae791a2d2 futex: Cleanup st... |
685 |
static inline void put_futex_key(union futex_key *key) |
1da177e4c Linux-2.6.12-rc2 |
686 |
{ |
38d47c1b7 futex: rely on ge... |
687 |
drop_futex_key_refs(key); |
1da177e4c Linux-2.6.12-rc2 |
688 |
} |
d96ee56ce futex: Make funct... |
689 690 |
/** * fault_in_user_writeable() - Fault in user address and verify RW access |
d0725992c futex: Fix the wr... |
691 692 693 694 695 |
* @uaddr: pointer to faulting user space address * * Slow path to fixup the fault we just took in the atomic write * access to @uaddr. * |
fb62db2ba futex: Fix kernel... |
696 |
* We have no generic implementation of a non-destructive write to the |
d0725992c futex: Fix the wr... |
697 698 699 700 701 702 |
* user address. We know that we faulted in the atomic pagefault * disabled section so we can as well avoid the #PF overhead by * calling get_user_pages() right away. */ static int fault_in_user_writeable(u32 __user *uaddr) { |
722d01723 futex: Take mmap_... |
703 704 705 706 |
struct mm_struct *mm = current->mm; int ret; down_read(&mm->mmap_sem); |
2efaca927 mm/futex: fix fut... |
707 |
ret = fixup_user_fault(current, mm, (unsigned long)uaddr, |
4a9e1cda2 mm: bring in addi... |
708 |
FAULT_FLAG_WRITE, NULL); |
722d01723 futex: Take mmap_... |
709 |
up_read(&mm->mmap_sem); |
d0725992c futex: Fix the wr... |
710 711 |
return ret < 0 ? ret : 0; } |
4b1c486b3 futex: add helper... |
712 713 |
/** * futex_top_waiter() - Return the highest priority waiter on a futex |
d96ee56ce futex: Make funct... |
714 715 |
* @hb: the hash bucket the futex_q's reside in * @key: the futex key (to distinguish it from other futex futex_q's) |
4b1c486b3 futex: add helper... |
716 717 718 719 720 721 722 723 724 725 726 727 728 729 |
* * Must be called with the hb lock held. */ static struct futex_q *futex_top_waiter(struct futex_hash_bucket *hb, union futex_key *key) { struct futex_q *this; plist_for_each_entry(this, &hb->chain, list) { if (match_futex(&this->key, key)) return this; } return NULL; } |
37a9d912b futex: Sanitize c... |
730 731 |
static int cmpxchg_futex_value_locked(u32 *curval, u32 __user *uaddr, u32 uval, u32 newval) |
36cf3b5c3 FUTEX: Tidy up th... |
732 |
{ |
37a9d912b futex: Sanitize c... |
733 |
int ret; |
36cf3b5c3 FUTEX: Tidy up th... |
734 735 |
pagefault_disable(); |
37a9d912b futex: Sanitize c... |
736 |
ret = futex_atomic_cmpxchg_inatomic(curval, uaddr, uval, newval); |
36cf3b5c3 FUTEX: Tidy up th... |
737 |
pagefault_enable(); |
37a9d912b futex: Sanitize c... |
738 |
return ret; |
36cf3b5c3 FUTEX: Tidy up th... |
739 740 741 |
} static int get_futex_value_locked(u32 *dest, u32 __user *from) |
1da177e4c Linux-2.6.12-rc2 |
742 743 |
{ int ret; |
a866374ae [PATCH] mm: pagef... |
744 |
pagefault_disable(); |
bd28b1459 x86: remove more ... |
745 |
ret = __get_user(*dest, from); |
a866374ae [PATCH] mm: pagef... |
746 |
pagefault_enable(); |
1da177e4c Linux-2.6.12-rc2 |
747 748 749 |
return ret ? -EFAULT : 0; } |
c87e2837b [PATCH] pi-futex:... |
750 751 752 753 754 755 756 757 758 759 |
/* * PI code: */ static int refill_pi_state_cache(void) { struct futex_pi_state *pi_state; if (likely(current->pi_state_cache)) return 0; |
4668edc33 [PATCH] kernel co... |
760 |
pi_state = kzalloc(sizeof(*pi_state), GFP_KERNEL); |
c87e2837b [PATCH] pi-futex:... |
761 762 763 |
if (!pi_state) return -ENOMEM; |
c87e2837b [PATCH] pi-futex:... |
764 765 766 767 |
INIT_LIST_HEAD(&pi_state->list); /* pi_mutex gets initialized later */ pi_state->owner = NULL; atomic_set(&pi_state->refcount, 1); |
38d47c1b7 futex: rely on ge... |
768 |
pi_state->key = FUTEX_KEY_INIT; |
c87e2837b [PATCH] pi-futex:... |
769 770 771 772 773 |
current->pi_state_cache = pi_state; return 0; } |
bf92cf3a5 futex: Cleanup re... |
774 |
static struct futex_pi_state *alloc_pi_state(void) |
c87e2837b [PATCH] pi-futex:... |
775 776 777 778 779 780 781 782 |
{ struct futex_pi_state *pi_state = current->pi_state_cache; WARN_ON(!pi_state); current->pi_state_cache = NULL; return pi_state; } |
bf92cf3a5 futex: Cleanup re... |
783 784 785 786 |
static void get_pi_state(struct futex_pi_state *pi_state) { WARN_ON_ONCE(!atomic_inc_not_zero(&pi_state->refcount)); } |
30a6b8031 futex: Fix a race... |
787 |
/* |
29e9ee5d4 futex: Rename fre... |
788 789 790 |
* Drops a reference to the pi_state object and frees or caches it * when the last reference is gone. * |
30a6b8031 futex: Fix a race... |
791 792 |
* Must be called with the hb lock held. */ |
29e9ee5d4 futex: Rename fre... |
793 |
static void put_pi_state(struct futex_pi_state *pi_state) |
c87e2837b [PATCH] pi-futex:... |
794 |
{ |
30a6b8031 futex: Fix a race... |
795 796 |
if (!pi_state) return; |
c87e2837b [PATCH] pi-futex:... |
797 798 799 800 801 802 803 804 |
if (!atomic_dec_and_test(&pi_state->refcount)) return; /* * If pi_state->owner is NULL, the owner is most probably dying * and has cleaned up the pi_state already */ if (pi_state->owner) { |
1d6154825 sched: Convert pi... |
805 |
raw_spin_lock_irq(&pi_state->owner->pi_lock); |
c87e2837b [PATCH] pi-futex:... |
806 |
list_del_init(&pi_state->list); |
1d6154825 sched: Convert pi... |
807 |
raw_spin_unlock_irq(&pi_state->owner->pi_lock); |
c87e2837b [PATCH] pi-futex:... |
808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 |
rt_mutex_proxy_unlock(&pi_state->pi_mutex, pi_state->owner); } if (current->pi_state_cache) kfree(pi_state); else { /* * pi_state->list is already empty. * clear pi_state->owner. * refcount is at 0 - put it back to 1. */ pi_state->owner = NULL; atomic_set(&pi_state->refcount, 1); current->pi_state_cache = pi_state; } } /* * Look up the task based on what TID userspace gave us. * We dont trust it. */ |
bf92cf3a5 futex: Cleanup re... |
830 |
static struct task_struct *futex_find_get_task(pid_t pid) |
c87e2837b [PATCH] pi-futex:... |
831 832 |
{ struct task_struct *p; |
d359b549b [PATCH] futex_fin... |
833 |
rcu_read_lock(); |
228ebcbe6 Uninline find_tas... |
834 |
p = find_task_by_vpid(pid); |
7a0ea09ad futex: futex_find... |
835 836 |
if (p) get_task_struct(p); |
a06381fec FUTEX: Restore th... |
837 |
|
d359b549b [PATCH] futex_fin... |
838 |
rcu_read_unlock(); |
c87e2837b [PATCH] pi-futex:... |
839 840 841 |
return p; } |
bc2eecd7e futex: Allow for ... |
842 |
#ifdef CONFIG_FUTEX_PI |
c87e2837b [PATCH] pi-futex:... |
843 844 845 846 847 848 849 |
/* * This task is holding PI mutexes at exit time => bad. * Kernel cleans up PI-state, but userspace is likely hosed. * (Robust-futex cleanup is separate and might save the day for userspace.) */ void exit_pi_state_list(struct task_struct *curr) { |
c87e2837b [PATCH] pi-futex:... |
850 851 |
struct list_head *next, *head = &curr->pi_state_list; struct futex_pi_state *pi_state; |
627371d73 [PATCH] pi-futex:... |
852 |
struct futex_hash_bucket *hb; |
38d47c1b7 futex: rely on ge... |
853 |
union futex_key key = FUTEX_KEY_INIT; |
c87e2837b [PATCH] pi-futex:... |
854 |
|
a0c1e9073 futex: runtime en... |
855 856 |
if (!futex_cmpxchg_enabled) return; |
c87e2837b [PATCH] pi-futex:... |
857 858 859 |
/* * We are a ZOMBIE and nobody can enqueue itself on * pi_state_list anymore, but we have to be careful |
627371d73 [PATCH] pi-futex:... |
860 |
* versus waiters unqueueing themselves: |
c87e2837b [PATCH] pi-futex:... |
861 |
*/ |
1d6154825 sched: Convert pi... |
862 |
raw_spin_lock_irq(&curr->pi_lock); |
c87e2837b [PATCH] pi-futex:... |
863 864 865 866 867 |
while (!list_empty(head)) { next = head->next; pi_state = list_entry(next, struct futex_pi_state, list); key = pi_state->key; |
627371d73 [PATCH] pi-futex:... |
868 |
hb = hash_futex(&key); |
1d6154825 sched: Convert pi... |
869 |
raw_spin_unlock_irq(&curr->pi_lock); |
c87e2837b [PATCH] pi-futex:... |
870 |
|
c87e2837b [PATCH] pi-futex:... |
871 |
spin_lock(&hb->lock); |
1d6154825 sched: Convert pi... |
872 |
raw_spin_lock_irq(&curr->pi_lock); |
627371d73 [PATCH] pi-futex:... |
873 874 875 876 |
/* * We dropped the pi-lock, so re-check whether this * task still owns the PI-state: */ |
c87e2837b [PATCH] pi-futex:... |
877 878 879 880 |
if (head->next != next) { spin_unlock(&hb->lock); continue; } |
c87e2837b [PATCH] pi-futex:... |
881 |
WARN_ON(pi_state->owner != curr); |
627371d73 [PATCH] pi-futex:... |
882 883 |
WARN_ON(list_empty(&pi_state->list)); list_del_init(&pi_state->list); |
c87e2837b [PATCH] pi-futex:... |
884 |
pi_state->owner = NULL; |
1d6154825 sched: Convert pi... |
885 |
raw_spin_unlock_irq(&curr->pi_lock); |
c87e2837b [PATCH] pi-futex:... |
886 |
|
16ffa12d7 futex: Pull rt_mu... |
887 |
get_pi_state(pi_state); |
c87e2837b [PATCH] pi-futex:... |
888 |
spin_unlock(&hb->lock); |
16ffa12d7 futex: Pull rt_mu... |
889 890 |
rt_mutex_futex_unlock(&pi_state->pi_mutex); put_pi_state(pi_state); |
1d6154825 sched: Convert pi... |
891 |
raw_spin_lock_irq(&curr->pi_lock); |
c87e2837b [PATCH] pi-futex:... |
892 |
} |
1d6154825 sched: Convert pi... |
893 |
raw_spin_unlock_irq(&curr->pi_lock); |
c87e2837b [PATCH] pi-futex:... |
894 |
} |
bc2eecd7e futex: Allow for ... |
895 |
#endif |
54a217887 futex: Make looku... |
896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 |
/* * We need to check the following states: * * Waiter | pi_state | pi->owner | uTID | uODIED | ? * * [1] NULL | --- | --- | 0 | 0/1 | Valid * [2] NULL | --- | --- | >0 | 0/1 | Valid * * [3] Found | NULL | -- | Any | 0/1 | Invalid * * [4] Found | Found | NULL | 0 | 1 | Valid * [5] Found | Found | NULL | >0 | 1 | Invalid * * [6] Found | Found | task | 0 | 1 | Valid * * [7] Found | Found | NULL | Any | 0 | Invalid * * [8] Found | Found | task | ==taskTID | 0/1 | Valid * [9] Found | Found | task | 0 | 0 | Invalid * [10] Found | Found | task | !=taskTID | 0/1 | Invalid * * [1] Indicates that the kernel can acquire the futex atomically. We * came came here due to a stale FUTEX_WAITERS/FUTEX_OWNER_DIED bit. * * [2] Valid, if TID does not belong to a kernel thread. If no matching * thread is found then it indicates that the owner TID has died. * * [3] Invalid. The waiter is queued on a non PI futex * * [4] Valid state after exit_robust_list(), which sets the user space * value to FUTEX_WAITERS | FUTEX_OWNER_DIED. * * [5] The user space value got manipulated between exit_robust_list() * and exit_pi_state_list() * * [6] Valid state after exit_pi_state_list() which sets the new owner in * the pi_state but cannot access the user space value. * * [7] pi_state->owner can only be NULL when the OWNER_DIED bit is set. * * [8] Owner and user space value match * * [9] There is no transient state which sets the user space TID to 0 * except exit_robust_list(), but this is indicated by the * FUTEX_OWNER_DIED bit. See [4] * * [10] There is no transient state which leaves owner and user space * TID out of sync. |
734009e96 futex: Change loc... |
944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 |
* * * Serialization and lifetime rules: * * hb->lock: * * hb -> futex_q, relation * futex_q -> pi_state, relation * * (cannot be raw because hb can contain arbitrary amount * of futex_q's) * * pi_mutex->wait_lock: * * {uval, pi_state} * * (and pi_mutex 'obviously') * * p->pi_lock: * * p->pi_state_list -> pi_state->list, relation * * pi_state->refcount: * * pi_state lifetime * * * Lock order: * * hb->lock * pi_mutex->wait_lock * p->pi_lock * |
54a217887 futex: Make looku... |
977 |
*/ |
e60cbc5ce futex: Split out ... |
978 979 980 981 982 983 |
/* * Validate that the existing waiter has a pi_state and sanity check * the pi_state against the user space value. If correct, attach to * it. */ |
734009e96 futex: Change loc... |
984 985 |
static int attach_to_pi_state(u32 __user *uaddr, u32 uval, struct futex_pi_state *pi_state, |
e60cbc5ce futex: Split out ... |
986 |
struct futex_pi_state **ps) |
c87e2837b [PATCH] pi-futex:... |
987 |
{ |
778e9a9c3 pi-futex: fix exi... |
988 |
pid_t pid = uval & FUTEX_TID_MASK; |
94ffac5d8 futex: Fix small ... |
989 990 |
u32 uval2; int ret; |
c87e2837b [PATCH] pi-futex:... |
991 |
|
e60cbc5ce futex: Split out ... |
992 993 994 995 996 |
/* * Userspace might have messed up non-PI and PI futexes [3] */ if (unlikely(!pi_state)) return -EINVAL; |
06a9ec291 [PATCH] pi-futex:... |
997 |
|
734009e96 futex: Change loc... |
998 999 1000 1001 1002 1003 |
/* * We get here with hb->lock held, and having found a * futex_top_waiter(). This means that futex_lock_pi() of said futex_q * has dropped the hb->lock in between queue_me() and unqueue_me_pi(), * which in turn means that futex_lock_pi() still has a reference on * our pi_state. |
16ffa12d7 futex: Pull rt_mu... |
1004 1005 1006 1007 1008 |
* * The waiter holding a reference on @pi_state also protects against * the unlocked put_pi_state() in futex_unlock_pi(), futex_lock_pi() * and futex_wait_requeue_pi() as it cannot go to 0 and consequently * free pi_state before we can take a reference ourselves. |
734009e96 futex: Change loc... |
1009 |
*/ |
e60cbc5ce futex: Split out ... |
1010 |
WARN_ON(!atomic_read(&pi_state->refcount)); |
59647b6ac futex: Handle fut... |
1011 |
|
e60cbc5ce futex: Split out ... |
1012 |
/* |
734009e96 futex: Change loc... |
1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 |
* Now that we have a pi_state, we can acquire wait_lock * and do the state validation. */ raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock); /* * Since {uval, pi_state} is serialized by wait_lock, and our current * uval was read without holding it, it can have changed. Verify it * still is what we expect it to be, otherwise retry the entire * operation. */ if (get_futex_value_locked(&uval2, uaddr)) goto out_efault; if (uval != uval2) goto out_eagain; /* |
e60cbc5ce futex: Split out ... |
1031 1032 1033 |
* Handle the owner died case: */ if (uval & FUTEX_OWNER_DIED) { |
bd1dbcc67 futex: Use futex_... |
1034 |
/* |
e60cbc5ce futex: Split out ... |
1035 1036 1037 |
* exit_pi_state_list sets owner to NULL and wakes the * topmost waiter. The task which acquires the * pi_state->rt_mutex will fixup owner. |
bd1dbcc67 futex: Use futex_... |
1038 |
*/ |
e60cbc5ce futex: Split out ... |
1039 |
if (!pi_state->owner) { |
59647b6ac futex: Handle fut... |
1040 |
/* |
e60cbc5ce futex: Split out ... |
1041 1042 |
* No pi state owner, but the user space TID * is not 0. Inconsistent state. [5] |
59647b6ac futex: Handle fut... |
1043 |
*/ |
e60cbc5ce futex: Split out ... |
1044 |
if (pid) |
734009e96 futex: Change loc... |
1045 |
goto out_einval; |
bd1dbcc67 futex: Use futex_... |
1046 |
/* |
e60cbc5ce futex: Split out ... |
1047 |
* Take a ref on the state and return success. [4] |
866293ee5 futex: Add anothe... |
1048 |
*/ |
734009e96 futex: Change loc... |
1049 |
goto out_attach; |
c87e2837b [PATCH] pi-futex:... |
1050 |
} |
bd1dbcc67 futex: Use futex_... |
1051 1052 |
/* |
e60cbc5ce futex: Split out ... |
1053 1054 1055 1056 1057 1058 1059 1060 |
* If TID is 0, then either the dying owner has not * yet executed exit_pi_state_list() or some waiter * acquired the rtmutex in the pi state, but did not * yet fixup the TID in user space. * * Take a ref on the state and return success. [6] */ if (!pid) |
734009e96 futex: Change loc... |
1061 |
goto out_attach; |
e60cbc5ce futex: Split out ... |
1062 1063 1064 1065 |
} else { /* * If the owner died bit is not set, then the pi_state * must have an owner. [7] |
bd1dbcc67 futex: Use futex_... |
1066 |
*/ |
e60cbc5ce futex: Split out ... |
1067 |
if (!pi_state->owner) |
734009e96 futex: Change loc... |
1068 |
goto out_einval; |
c87e2837b [PATCH] pi-futex:... |
1069 1070 1071 |
} /* |
e60cbc5ce futex: Split out ... |
1072 1073 1074 1075 1076 |
* Bail out if user space manipulated the futex value. If pi * state exists then the owner TID must be the same as the * user space TID. [9/10] */ if (pid != task_pid_vnr(pi_state->owner)) |
734009e96 futex: Change loc... |
1077 1078 1079 |
goto out_einval; out_attach: |
bf92cf3a5 futex: Cleanup re... |
1080 |
get_pi_state(pi_state); |
734009e96 futex: Change loc... |
1081 |
raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock); |
e60cbc5ce futex: Split out ... |
1082 1083 |
*ps = pi_state; return 0; |
734009e96 futex: Change loc... |
1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 |
out_einval: ret = -EINVAL; goto out_error; out_eagain: ret = -EAGAIN; goto out_error; out_efault: ret = -EFAULT; goto out_error; out_error: raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock); return ret; |
e60cbc5ce futex: Split out ... |
1100 |
} |
04e1b2e52 futex: Split out ... |
1101 1102 1103 1104 1105 1106 |
/* * Lookup the task for the TID provided from user space and attach to * it after doing proper sanity checks. */ static int attach_to_pi_owner(u32 uval, union futex_key *key, struct futex_pi_state **ps) |
e60cbc5ce futex: Split out ... |
1107 |
{ |
e60cbc5ce futex: Split out ... |
1108 |
pid_t pid = uval & FUTEX_TID_MASK; |
04e1b2e52 futex: Split out ... |
1109 1110 |
struct futex_pi_state *pi_state; struct task_struct *p; |
e60cbc5ce futex: Split out ... |
1111 1112 |
/* |
e3f2ddeac [PATCH] pi-futex:... |
1113 |
* We are the first waiter - try to look up the real owner and attach |
54a217887 futex: Make looku... |
1114 |
* the new pi_state to it, but bail out when TID = 0 [1] |
c87e2837b [PATCH] pi-futex:... |
1115 |
*/ |
778e9a9c3 pi-futex: fix exi... |
1116 |
if (!pid) |
e3f2ddeac [PATCH] pi-futex:... |
1117 |
return -ESRCH; |
c87e2837b [PATCH] pi-futex:... |
1118 |
p = futex_find_get_task(pid); |
7a0ea09ad futex: futex_find... |
1119 1120 |
if (!p) return -ESRCH; |
778e9a9c3 pi-futex: fix exi... |
1121 |
|
a21294644 locking/futex: Ch... |
1122 |
if (unlikely(p->flags & PF_KTHREAD)) { |
f0d71b3dc futex: Prevent at... |
1123 1124 1125 |
put_task_struct(p); return -EPERM; } |
778e9a9c3 pi-futex: fix exi... |
1126 1127 1128 1129 1130 1131 |
/* * We need to look at the task state flags to figure out, * whether the task is exiting. To protect against the do_exit * change of the task flags, we do this protected by * p->pi_lock: */ |
1d6154825 sched: Convert pi... |
1132 |
raw_spin_lock_irq(&p->pi_lock); |
778e9a9c3 pi-futex: fix exi... |
1133 1134 1135 1136 1137 1138 1139 |
if (unlikely(p->flags & PF_EXITING)) { /* * The task is on the way out. When PF_EXITPIDONE is * set, we know that the task has finished the * cleanup: */ int ret = (p->flags & PF_EXITPIDONE) ? -ESRCH : -EAGAIN; |
1d6154825 sched: Convert pi... |
1140 |
raw_spin_unlock_irq(&p->pi_lock); |
778e9a9c3 pi-futex: fix exi... |
1141 1142 1143 |
put_task_struct(p); return ret; } |
c87e2837b [PATCH] pi-futex:... |
1144 |
|
54a217887 futex: Make looku... |
1145 1146 |
/* * No existing pi state. First waiter. [2] |
734009e96 futex: Change loc... |
1147 1148 1149 |
* * This creates pi_state, we have hb->lock held, this means nothing can * observe this state, wait_lock is irrelevant. |
54a217887 futex: Make looku... |
1150 |
*/ |
c87e2837b [PATCH] pi-futex:... |
1151 1152 1153 |
pi_state = alloc_pi_state(); /* |
04e1b2e52 futex: Split out ... |
1154 |
* Initialize the pi_mutex in locked state and make @p |
c87e2837b [PATCH] pi-futex:... |
1155 1156 1157 1158 1159 |
* the owner of it: */ rt_mutex_init_proxy_locked(&pi_state->pi_mutex, p); /* Store the key for possible exit cleanups: */ |
d0aa7a70b futex_requeue_pi ... |
1160 |
pi_state->key = *key; |
c87e2837b [PATCH] pi-futex:... |
1161 |
|
627371d73 [PATCH] pi-futex:... |
1162 |
WARN_ON(!list_empty(&pi_state->list)); |
c87e2837b [PATCH] pi-futex:... |
1163 1164 |
list_add(&pi_state->list, &p->pi_state_list); pi_state->owner = p; |
1d6154825 sched: Convert pi... |
1165 |
raw_spin_unlock_irq(&p->pi_lock); |
c87e2837b [PATCH] pi-futex:... |
1166 1167 |
put_task_struct(p); |
d0aa7a70b futex_requeue_pi ... |
1168 |
*ps = pi_state; |
c87e2837b [PATCH] pi-futex:... |
1169 1170 1171 |
return 0; } |
734009e96 futex: Change loc... |
1172 1173 |
static int lookup_pi_state(u32 __user *uaddr, u32 uval, struct futex_hash_bucket *hb, |
04e1b2e52 futex: Split out ... |
1174 1175 |
union futex_key *key, struct futex_pi_state **ps) { |
499f5aca2 futex: Cleanup va... |
1176 |
struct futex_q *top_waiter = futex_top_waiter(hb, key); |
04e1b2e52 futex: Split out ... |
1177 1178 1179 1180 1181 |
/* * If there is a waiter on that futex, validate it and * attach to the pi_state when the validation succeeds. */ |
499f5aca2 futex: Cleanup va... |
1182 |
if (top_waiter) |
734009e96 futex: Change loc... |
1183 |
return attach_to_pi_state(uaddr, uval, top_waiter->pi_state, ps); |
04e1b2e52 futex: Split out ... |
1184 1185 1186 1187 1188 1189 1190 |
/* * We are the first waiter - try to look up the owner based on * @uval and attach to it. */ return attach_to_pi_owner(uval, key, ps); } |
af54d6a1c futex: Simplify f... |
1191 1192 1193 |
static int lock_pi_update_atomic(u32 __user *uaddr, u32 uval, u32 newval) { u32 uninitialized_var(curval); |
ab51fbab3 futex: Fault/erro... |
1194 1195 |
if (unlikely(should_fail_futex(true))) return -EFAULT; |
af54d6a1c futex: Simplify f... |
1196 1197 |
if (unlikely(cmpxchg_futex_value_locked(&curval, uaddr, uval, newval))) return -EFAULT; |
734009e96 futex: Change loc... |
1198 |
/* If user space value changed, let the caller retry */ |
af54d6a1c futex: Simplify f... |
1199 1200 |
return curval != uval ? -EAGAIN : 0; } |
1a52084d0 futex: split out ... |
1201 |
/** |
d96ee56ce futex: Make funct... |
1202 |
* futex_lock_pi_atomic() - Atomic work required to acquire a pi aware futex |
bab5bc9e8 futex: fixup unlo... |
1203 1204 1205 1206 1207 1208 1209 1210 |
* @uaddr: the pi futex user address * @hb: the pi futex hash bucket * @key: the futex key associated with uaddr and hb * @ps: the pi_state pointer where we store the result of the * lookup * @task: the task to perform the atomic lock work for. This will * be "current" except in the case of requeue pi. * @set_waiters: force setting the FUTEX_WAITERS bit (1) or not (0) |
1a52084d0 futex: split out ... |
1211 |
* |
6c23cbbd5 futex: fix kernel... |
1212 |
* Return: |
7b4ff1adb mutex, futex: adj... |
1213 1214 1215 |
* - 0 - ready to wait; * - 1 - acquired the lock; * - <0 - error |
1a52084d0 futex: split out ... |
1216 1217 1218 1219 1220 1221 |
* * The hb->lock and futex_key refs shall be held by the caller. */ static int futex_lock_pi_atomic(u32 __user *uaddr, struct futex_hash_bucket *hb, union futex_key *key, struct futex_pi_state **ps, |
bab5bc9e8 futex: fixup unlo... |
1222 |
struct task_struct *task, int set_waiters) |
1a52084d0 futex: split out ... |
1223 |
{ |
af54d6a1c futex: Simplify f... |
1224 |
u32 uval, newval, vpid = task_pid_vnr(task); |
499f5aca2 futex: Cleanup va... |
1225 |
struct futex_q *top_waiter; |
af54d6a1c futex: Simplify f... |
1226 |
int ret; |
1a52084d0 futex: split out ... |
1227 1228 |
/* |
af54d6a1c futex: Simplify f... |
1229 1230 |
* Read the user space value first so we can validate a few * things before proceeding further. |
1a52084d0 futex: split out ... |
1231 |
*/ |
af54d6a1c futex: Simplify f... |
1232 |
if (get_futex_value_locked(&uval, uaddr)) |
1a52084d0 futex: split out ... |
1233 |
return -EFAULT; |
ab51fbab3 futex: Fault/erro... |
1234 1235 |
if (unlikely(should_fail_futex(true))) return -EFAULT; |
1a52084d0 futex: split out ... |
1236 1237 1238 |
/* * Detect deadlocks. */ |
af54d6a1c futex: Simplify f... |
1239 |
if ((unlikely((uval & FUTEX_TID_MASK) == vpid))) |
1a52084d0 futex: split out ... |
1240 |
return -EDEADLK; |
ab51fbab3 futex: Fault/erro... |
1241 1242 |
if ((unlikely(should_fail_futex(true)))) return -EDEADLK; |
1a52084d0 futex: split out ... |
1243 |
/* |
af54d6a1c futex: Simplify f... |
1244 1245 |
* Lookup existing state first. If it exists, try to attach to * its pi_state. |
1a52084d0 futex: split out ... |
1246 |
*/ |
499f5aca2 futex: Cleanup va... |
1247 1248 |
top_waiter = futex_top_waiter(hb, key); if (top_waiter) |
734009e96 futex: Change loc... |
1249 |
return attach_to_pi_state(uaddr, uval, top_waiter->pi_state, ps); |
1a52084d0 futex: split out ... |
1250 1251 |
/* |
af54d6a1c futex: Simplify f... |
1252 1253 1254 1255 |
* No waiter and user TID is 0. We are here because the * waiters or the owner died bit is set or called from * requeue_cmp_pi or for whatever reason something took the * syscall. |
1a52084d0 futex: split out ... |
1256 |
*/ |
af54d6a1c futex: Simplify f... |
1257 |
if (!(uval & FUTEX_TID_MASK)) { |
59fa62451 futex: Handle fut... |
1258 |
/* |
af54d6a1c futex: Simplify f... |
1259 1260 |
* We take over the futex. No other waiters and the user space * TID is 0. We preserve the owner died bit. |
59fa62451 futex: Handle fut... |
1261 |
*/ |
af54d6a1c futex: Simplify f... |
1262 1263 |
newval = uval & FUTEX_OWNER_DIED; newval |= vpid; |
1a52084d0 futex: split out ... |
1264 |
|
af54d6a1c futex: Simplify f... |
1265 1266 1267 1268 1269 1270 1271 1272 |
/* The futex requeue_pi code can enforce the waiters bit */ if (set_waiters) newval |= FUTEX_WAITERS; ret = lock_pi_update_atomic(uaddr, uval, newval); /* If the take over worked, return 1 */ return ret < 0 ? ret : 1; } |
1a52084d0 futex: split out ... |
1273 1274 |
/* |
af54d6a1c futex: Simplify f... |
1275 1276 1277 |
* First waiter. Set the waiters bit before attaching ourself to * the owner. If owner tries to unlock, it will be forced into * the kernel and blocked on hb->lock. |
1a52084d0 futex: split out ... |
1278 |
*/ |
af54d6a1c futex: Simplify f... |
1279 1280 1281 1282 |
newval = uval | FUTEX_WAITERS; ret = lock_pi_update_atomic(uaddr, uval, newval); if (ret) return ret; |
1a52084d0 futex: split out ... |
1283 |
/* |
af54d6a1c futex: Simplify f... |
1284 1285 1286 |
* If the update of the user space value succeeded, we try to * attach to the owner. If that fails, no harm done, we only * set the FUTEX_WAITERS bit in the user space variable. |
1a52084d0 futex: split out ... |
1287 |
*/ |
af54d6a1c futex: Simplify f... |
1288 |
return attach_to_pi_owner(uval, key, ps); |
1a52084d0 futex: split out ... |
1289 |
} |
2e12978a9 futex,plist: Pass... |
1290 1291 1292 1293 1294 1295 1296 1297 1298 |
/** * __unqueue_futex() - Remove the futex_q from its futex_hash_bucket * @q: The futex_q to unqueue * * The q->lock_ptr must not be NULL and must be held by the caller. */ static void __unqueue_futex(struct futex_q *q) { struct futex_hash_bucket *hb; |
290962021 futex: Fix WARN_O... |
1299 1300 |
if (WARN_ON_SMP(!q->lock_ptr || !spin_is_locked(q->lock_ptr)) || WARN_ON(plist_node_empty(&q->list))) |
2e12978a9 futex,plist: Pass... |
1301 1302 1303 1304 |
return; hb = container_of(q->lock_ptr, struct futex_hash_bucket, lock); plist_del(&q->list, &hb->chain); |
11d4616bd futex: revert bac... |
1305 |
hb_waiters_dec(hb); |
2e12978a9 futex,plist: Pass... |
1306 |
} |
c87e2837b [PATCH] pi-futex:... |
1307 |
/* |
1da177e4c Linux-2.6.12-rc2 |
1308 |
* The hash bucket lock must be held when this is called. |
1d0dcb3ad futex: Implement ... |
1309 1310 1311 |
* Afterwards, the futex_q must not be accessed. Callers * must ensure to later call wake_up_q() for the actual * wakeups to occur. |
1da177e4c Linux-2.6.12-rc2 |
1312 |
*/ |
1d0dcb3ad futex: Implement ... |
1313 |
static void mark_wake_futex(struct wake_q_head *wake_q, struct futex_q *q) |
1da177e4c Linux-2.6.12-rc2 |
1314 |
{ |
f1a11e057 futex: remove the... |
1315 |
struct task_struct *p = q->task; |
aa10990e0 futex: avoid wake... |
1316 1317 1318 |
if (WARN(q->pi_state || q->rt_waiter, "refusing to wake PI futex ")) return; |
1da177e4c Linux-2.6.12-rc2 |
1319 |
/* |
1d0dcb3ad futex: Implement ... |
1320 1321 |
* Queue the task for later wakeup for after we've released * the hb->lock. wake_q_add() grabs reference to p. |
1da177e4c Linux-2.6.12-rc2 |
1322 |
*/ |
1d0dcb3ad futex: Implement ... |
1323 |
wake_q_add(wake_q, p); |
2e12978a9 futex,plist: Pass... |
1324 |
__unqueue_futex(q); |
1da177e4c Linux-2.6.12-rc2 |
1325 |
/* |
38fcd06e9 futex: Clarify ma... |
1326 1327 1328 1329 1330 |
* The waiting task can free the futex_q as soon as q->lock_ptr = NULL * is written, without taking any locks. This is possible in the event * of a spurious wakeup, for example. A memory barrier is required here * to prevent the following store to lock_ptr from getting ahead of the * plist_del in __unqueue_futex(). |
1da177e4c Linux-2.6.12-rc2 |
1331 |
*/ |
1b367ece0 futex: Use smp_st... |
1332 |
smp_store_release(&q->lock_ptr, NULL); |
1da177e4c Linux-2.6.12-rc2 |
1333 |
} |
16ffa12d7 futex: Pull rt_mu... |
1334 1335 1336 1337 |
/* * Caller must hold a reference on @pi_state. */ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_pi_state *pi_state) |
c87e2837b [PATCH] pi-futex:... |
1338 |
{ |
7cfdaf38d futex: uninitiali... |
1339 |
u32 uninitialized_var(curval), newval; |
16ffa12d7 futex: Pull rt_mu... |
1340 |
struct task_struct *new_owner; |
aa2bfe553 rtmutex: Clean up |
1341 |
bool postunlock = false; |
194a6b5b9 sched/wake_q: Ren... |
1342 |
DEFINE_WAKE_Q(wake_q); |
13fbca4c6 futex: Always cle... |
1343 |
int ret = 0; |
c87e2837b [PATCH] pi-futex:... |
1344 |
|
c87e2837b [PATCH] pi-futex:... |
1345 |
new_owner = rt_mutex_next_owner(&pi_state->pi_mutex); |
bebe5b514 futex: Futex_unlo... |
1346 |
if (WARN_ON_ONCE(!new_owner)) { |
16ffa12d7 futex: Pull rt_mu... |
1347 |
/* |
bebe5b514 futex: Futex_unlo... |
1348 |
* As per the comment in futex_unlock_pi() this should not happen. |
16ffa12d7 futex: Pull rt_mu... |
1349 1350 1351 1352 1353 1354 1355 1356 |
* * When this happens, give up our locks and try again, giving * the futex_lock_pi() instance time to complete, either by * waiting on the rtmutex or removing itself from the futex * queue. */ ret = -EAGAIN; goto out_unlock; |
73d786bd0 futex: Rework inc... |
1357 |
} |
c87e2837b [PATCH] pi-futex:... |
1358 1359 |
/* |
16ffa12d7 futex: Pull rt_mu... |
1360 1361 1362 |
* We pass it to the next owner. The WAITERS bit is always kept * enabled while there is PI state around. We cleanup the owner * died bit, because we are the owner. |
c87e2837b [PATCH] pi-futex:... |
1363 |
*/ |
13fbca4c6 futex: Always cle... |
1364 |
newval = FUTEX_WAITERS | task_pid_vnr(new_owner); |
e3f2ddeac [PATCH] pi-futex:... |
1365 |
|
ab51fbab3 futex: Fault/erro... |
1366 1367 |
if (unlikely(should_fail_futex(true))) ret = -EFAULT; |
89e9e66ba futex: Handle unl... |
1368 |
if (cmpxchg_futex_value_locked(&curval, uaddr, uval, newval)) { |
13fbca4c6 futex: Always cle... |
1369 |
ret = -EFAULT; |
734009e96 futex: Change loc... |
1370 |
|
89e9e66ba futex: Handle unl... |
1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 |
} else if (curval != uval) { /* * If a unconditional UNLOCK_PI operation (user space did not * try the TID->0 transition) raced with a waiter setting the * FUTEX_WAITERS flag between get_user() and locking the hash * bucket lock, retry the operation. */ if ((FUTEX_TID_MASK & curval) == uval) ret = -EAGAIN; else ret = -EINVAL; } |
734009e96 futex: Change loc... |
1383 |
|
16ffa12d7 futex: Pull rt_mu... |
1384 1385 |
if (ret) goto out_unlock; |
c87e2837b [PATCH] pi-futex:... |
1386 |
|
94ffac5d8 futex: Fix small ... |
1387 1388 1389 1390 |
/* * This is a point of no return; once we modify the uval there is no * going back and subsequent operations must not fail. */ |
b4abf9104 rtmutex: Make wai... |
1391 |
raw_spin_lock(&pi_state->owner->pi_lock); |
627371d73 [PATCH] pi-futex:... |
1392 1393 |
WARN_ON(list_empty(&pi_state->list)); list_del_init(&pi_state->list); |
b4abf9104 rtmutex: Make wai... |
1394 |
raw_spin_unlock(&pi_state->owner->pi_lock); |
627371d73 [PATCH] pi-futex:... |
1395 |
|
b4abf9104 rtmutex: Make wai... |
1396 |
raw_spin_lock(&new_owner->pi_lock); |
627371d73 [PATCH] pi-futex:... |
1397 |
WARN_ON(!list_empty(&pi_state->list)); |
c87e2837b [PATCH] pi-futex:... |
1398 1399 |
list_add(&pi_state->list, &new_owner->pi_state_list); pi_state->owner = new_owner; |
b4abf9104 rtmutex: Make wai... |
1400 |
raw_spin_unlock(&new_owner->pi_lock); |
627371d73 [PATCH] pi-futex:... |
1401 |
|
aa2bfe553 rtmutex: Clean up |
1402 |
postunlock = __rt_mutex_futex_unlock(&pi_state->pi_mutex, &wake_q); |
5293c2efd futex,rt_mutex: P... |
1403 |
|
16ffa12d7 futex: Pull rt_mu... |
1404 |
out_unlock: |
5293c2efd futex,rt_mutex: P... |
1405 |
raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock); |
5293c2efd futex,rt_mutex: P... |
1406 |
|
aa2bfe553 rtmutex: Clean up |
1407 1408 |
if (postunlock) rt_mutex_postunlock(&wake_q); |
c87e2837b [PATCH] pi-futex:... |
1409 |
|
16ffa12d7 futex: Pull rt_mu... |
1410 |
return ret; |
c87e2837b [PATCH] pi-futex:... |
1411 |
} |
1da177e4c Linux-2.6.12-rc2 |
1412 |
/* |
8b8f319fc [PATCH] lockdep: ... |
1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 |
* Express the locking dependencies for lockdep: */ static inline void double_lock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2) { if (hb1 <= hb2) { spin_lock(&hb1->lock); if (hb1 < hb2) spin_lock_nested(&hb2->lock, SINGLE_DEPTH_NESTING); } else { /* hb1 > hb2 */ spin_lock(&hb2->lock); spin_lock_nested(&hb1->lock, SINGLE_DEPTH_NESTING); } } |
5eb3dc62f futex: add double... |
1427 1428 1429 |
static inline void double_unlock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2) { |
f061d3515 futex: remove the... |
1430 |
spin_unlock(&hb1->lock); |
88f502fed futex: remove the... |
1431 1432 |
if (hb1 != hb2) spin_unlock(&hb2->lock); |
5eb3dc62f futex: add double... |
1433 |
} |
8b8f319fc [PATCH] lockdep: ... |
1434 |
/* |
b2d0994b1 futex: update fut... |
1435 |
* Wake up waiters matching bitset queued on this futex (uaddr). |
1da177e4c Linux-2.6.12-rc2 |
1436 |
*/ |
b41277dc7 futex: Replace fs... |
1437 1438 |
static int futex_wake(u32 __user *uaddr, unsigned int flags, int nr_wake, u32 bitset) |
1da177e4c Linux-2.6.12-rc2 |
1439 |
{ |
e2970f2fb [PATCH] pi-futex:... |
1440 |
struct futex_hash_bucket *hb; |
1da177e4c Linux-2.6.12-rc2 |
1441 |
struct futex_q *this, *next; |
38d47c1b7 futex: rely on ge... |
1442 |
union futex_key key = FUTEX_KEY_INIT; |
1da177e4c Linux-2.6.12-rc2 |
1443 |
int ret; |
194a6b5b9 sched/wake_q: Ren... |
1444 |
DEFINE_WAKE_Q(wake_q); |
1da177e4c Linux-2.6.12-rc2 |
1445 |
|
cd689985c futex: Add bitset... |
1446 1447 |
if (!bitset) return -EINVAL; |
9ea71503a futex: Fix regres... |
1448 |
ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &key, VERIFY_READ); |
1da177e4c Linux-2.6.12-rc2 |
1449 1450 |
if (unlikely(ret != 0)) goto out; |
e2970f2fb [PATCH] pi-futex:... |
1451 |
hb = hash_futex(&key); |
b0c29f79e futexes: Avoid ta... |
1452 1453 1454 1455 |
/* Make sure we really have tasks to wakeup */ if (!hb_waiters_pending(hb)) goto out_put_key; |
e2970f2fb [PATCH] pi-futex:... |
1456 |
spin_lock(&hb->lock); |
1da177e4c Linux-2.6.12-rc2 |
1457 |
|
0d00c7b20 futexes: Clean up... |
1458 |
plist_for_each_entry_safe(this, next, &hb->chain, list) { |
1da177e4c Linux-2.6.12-rc2 |
1459 |
if (match_futex (&this->key, &key)) { |
52400ba94 futex: add requeu... |
1460 |
if (this->pi_state || this->rt_waiter) { |
ed6f7b10e [PATCH] pi-futex:... |
1461 1462 1463 |
ret = -EINVAL; break; } |
cd689985c futex: Add bitset... |
1464 1465 1466 1467 |
/* Check if one of the bits is set in both bitsets */ if (!(this->bitset & bitset)) continue; |
1d0dcb3ad futex: Implement ... |
1468 |
mark_wake_futex(&wake_q, this); |
1da177e4c Linux-2.6.12-rc2 |
1469 1470 1471 1472 |
if (++ret >= nr_wake) break; } } |
e2970f2fb [PATCH] pi-futex:... |
1473 |
spin_unlock(&hb->lock); |
1d0dcb3ad futex: Implement ... |
1474 |
wake_up_q(&wake_q); |
b0c29f79e futexes: Avoid ta... |
1475 |
out_put_key: |
ae791a2d2 futex: Cleanup st... |
1476 |
put_futex_key(&key); |
42d35d48c futex: make futex... |
1477 |
out: |
1da177e4c Linux-2.6.12-rc2 |
1478 1479 |
return ret; } |
30d6e0a41 futex: Remove dup... |
1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 |
static int futex_atomic_op_inuser(unsigned int encoded_op, u32 __user *uaddr) { unsigned int op = (encoded_op & 0x70000000) >> 28; unsigned int cmp = (encoded_op & 0x0f000000) >> 24; int oparg = sign_extend32((encoded_op & 0x00fff000) >> 12, 12); int cmparg = sign_extend32(encoded_op & 0x00000fff, 12); int oldval, ret; if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28)) { if (oparg < 0 || oparg > 31) return -EINVAL; oparg = 1 << oparg; } if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32))) return -EFAULT; ret = arch_futex_atomic_op_inuser(op, oparg, &oldval, uaddr); if (ret) return ret; switch (cmp) { case FUTEX_OP_CMP_EQ: return oldval == cmparg; case FUTEX_OP_CMP_NE: return oldval != cmparg; case FUTEX_OP_CMP_LT: return oldval < cmparg; case FUTEX_OP_CMP_GE: return oldval >= cmparg; case FUTEX_OP_CMP_LE: return oldval <= cmparg; case FUTEX_OP_CMP_GT: return oldval > cmparg; default: return -ENOSYS; } } |
1da177e4c Linux-2.6.12-rc2 |
1518 |
/* |
4732efbeb [PATCH] FUTEX_WAK... |
1519 1520 1521 |
* Wake up all waiters hashed on the physical page that is mapped * to this virtual address: */ |
e2970f2fb [PATCH] pi-futex:... |
1522 |
static int |
b41277dc7 futex: Replace fs... |
1523 |
futex_wake_op(u32 __user *uaddr1, unsigned int flags, u32 __user *uaddr2, |
e2970f2fb [PATCH] pi-futex:... |
1524 |
int nr_wake, int nr_wake2, int op) |
4732efbeb [PATCH] FUTEX_WAK... |
1525 |
{ |
38d47c1b7 futex: rely on ge... |
1526 |
union futex_key key1 = FUTEX_KEY_INIT, key2 = FUTEX_KEY_INIT; |
e2970f2fb [PATCH] pi-futex:... |
1527 |
struct futex_hash_bucket *hb1, *hb2; |
4732efbeb [PATCH] FUTEX_WAK... |
1528 |
struct futex_q *this, *next; |
e4dc5b7a3 futex: clean up f... |
1529 |
int ret, op_ret; |
194a6b5b9 sched/wake_q: Ren... |
1530 |
DEFINE_WAKE_Q(wake_q); |
4732efbeb [PATCH] FUTEX_WAK... |
1531 |
|
e4dc5b7a3 futex: clean up f... |
1532 |
retry: |
9ea71503a futex: Fix regres... |
1533 |
ret = get_futex_key(uaddr1, flags & FLAGS_SHARED, &key1, VERIFY_READ); |
4732efbeb [PATCH] FUTEX_WAK... |
1534 1535 |
if (unlikely(ret != 0)) goto out; |
9ea71503a futex: Fix regres... |
1536 |
ret = get_futex_key(uaddr2, flags & FLAGS_SHARED, &key2, VERIFY_WRITE); |
4732efbeb [PATCH] FUTEX_WAK... |
1537 |
if (unlikely(ret != 0)) |
42d35d48c futex: make futex... |
1538 |
goto out_put_key1; |
4732efbeb [PATCH] FUTEX_WAK... |
1539 |
|
e2970f2fb [PATCH] pi-futex:... |
1540 1541 |
hb1 = hash_futex(&key1); hb2 = hash_futex(&key2); |
4732efbeb [PATCH] FUTEX_WAK... |
1542 |
|
e4dc5b7a3 futex: clean up f... |
1543 |
retry_private: |
eaaea8036 futex: Fix lockin... |
1544 |
double_lock_hb(hb1, hb2); |
e2970f2fb [PATCH] pi-futex:... |
1545 |
op_ret = futex_atomic_op_inuser(op, uaddr2); |
4732efbeb [PATCH] FUTEX_WAK... |
1546 |
if (unlikely(op_ret < 0)) { |
4732efbeb [PATCH] FUTEX_WAK... |
1547 |
|
5eb3dc62f futex: add double... |
1548 |
double_unlock_hb(hb1, hb2); |
4732efbeb [PATCH] FUTEX_WAK... |
1549 |
|
7ee1dd3fe [PATCH] FRV: Make... |
1550 |
#ifndef CONFIG_MMU |
e2970f2fb [PATCH] pi-futex:... |
1551 1552 1553 1554 |
/* * we don't get EFAULT from MMU faults if we don't have an MMU, * but we might get them from range checking */ |
7ee1dd3fe [PATCH] FRV: Make... |
1555 |
ret = op_ret; |
42d35d48c futex: make futex... |
1556 |
goto out_put_keys; |
7ee1dd3fe [PATCH] FRV: Make... |
1557 |
#endif |
796f8d9b9 [PATCH] FUTEX_WAK... |
1558 1559 |
if (unlikely(op_ret != -EFAULT)) { ret = op_ret; |
42d35d48c futex: make futex... |
1560 |
goto out_put_keys; |
796f8d9b9 [PATCH] FUTEX_WAK... |
1561 |
} |
d0725992c futex: Fix the wr... |
1562 |
ret = fault_in_user_writeable(uaddr2); |
4732efbeb [PATCH] FUTEX_WAK... |
1563 |
if (ret) |
de87fcc12 futex: additional... |
1564 |
goto out_put_keys; |
4732efbeb [PATCH] FUTEX_WAK... |
1565 |
|
b41277dc7 futex: Replace fs... |
1566 |
if (!(flags & FLAGS_SHARED)) |
e4dc5b7a3 futex: clean up f... |
1567 |
goto retry_private; |
ae791a2d2 futex: Cleanup st... |
1568 1569 |
put_futex_key(&key2); put_futex_key(&key1); |
e4dc5b7a3 futex: clean up f... |
1570 |
goto retry; |
4732efbeb [PATCH] FUTEX_WAK... |
1571 |
} |
0d00c7b20 futexes: Clean up... |
1572 |
plist_for_each_entry_safe(this, next, &hb1->chain, list) { |
4732efbeb [PATCH] FUTEX_WAK... |
1573 |
if (match_futex (&this->key, &key1)) { |
aa10990e0 futex: avoid wake... |
1574 1575 1576 1577 |
if (this->pi_state || this->rt_waiter) { ret = -EINVAL; goto out_unlock; } |
1d0dcb3ad futex: Implement ... |
1578 |
mark_wake_futex(&wake_q, this); |
4732efbeb [PATCH] FUTEX_WAK... |
1579 1580 1581 1582 1583 1584 |
if (++ret >= nr_wake) break; } } if (op_ret > 0) { |
4732efbeb [PATCH] FUTEX_WAK... |
1585 |
op_ret = 0; |
0d00c7b20 futexes: Clean up... |
1586 |
plist_for_each_entry_safe(this, next, &hb2->chain, list) { |
4732efbeb [PATCH] FUTEX_WAK... |
1587 |
if (match_futex (&this->key, &key2)) { |
aa10990e0 futex: avoid wake... |
1588 1589 1590 1591 |
if (this->pi_state || this->rt_waiter) { ret = -EINVAL; goto out_unlock; } |
1d0dcb3ad futex: Implement ... |
1592 |
mark_wake_futex(&wake_q, this); |
4732efbeb [PATCH] FUTEX_WAK... |
1593 1594 1595 1596 1597 1598 |
if (++op_ret >= nr_wake2) break; } } ret += op_ret; } |
aa10990e0 futex: avoid wake... |
1599 |
out_unlock: |
5eb3dc62f futex: add double... |
1600 |
double_unlock_hb(hb1, hb2); |
1d0dcb3ad futex: Implement ... |
1601 |
wake_up_q(&wake_q); |
42d35d48c futex: make futex... |
1602 |
out_put_keys: |
ae791a2d2 futex: Cleanup st... |
1603 |
put_futex_key(&key2); |
42d35d48c futex: make futex... |
1604 |
out_put_key1: |
ae791a2d2 futex: Cleanup st... |
1605 |
put_futex_key(&key1); |
42d35d48c futex: make futex... |
1606 |
out: |
4732efbeb [PATCH] FUTEX_WAK... |
1607 1608 |
return ret; } |
9121e4783 futex: distangle ... |
1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 |
/** * requeue_futex() - Requeue a futex_q from one hb to another * @q: the futex_q to requeue * @hb1: the source hash_bucket * @hb2: the target hash_bucket * @key2: the new key for the requeued futex_q */ static inline void requeue_futex(struct futex_q *q, struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2, union futex_key *key2) { /* * If key1 and key2 hash to the same bucket, no need to * requeue. */ if (likely(&hb1->chain != &hb2->chain)) { plist_del(&q->list, &hb1->chain); |
11d4616bd futex: revert bac... |
1627 |
hb_waiters_dec(hb1); |
11d4616bd futex: revert bac... |
1628 |
hb_waiters_inc(hb2); |
fe1bce9e2 futex: Acknowledg... |
1629 |
plist_add(&q->list, &hb2->chain); |
9121e4783 futex: distangle ... |
1630 |
q->lock_ptr = &hb2->lock; |
9121e4783 futex: distangle ... |
1631 1632 1633 1634 |
} get_futex_key_refs(key2); q->key = *key2; } |
52400ba94 futex: add requeu... |
1635 1636 |
/** * requeue_pi_wake_futex() - Wake a task that acquired the lock during requeue |
d96ee56ce futex: Make funct... |
1637 1638 1639 |
* @q: the futex_q * @key: the key of the requeue target futex * @hb: the hash_bucket of the requeue target futex |
52400ba94 futex: add requeu... |
1640 1641 1642 1643 1644 |
* * During futex_requeue, with requeue_pi=1, it is possible to acquire the * target futex if it is uncontended or via a lock steal. Set the futex_q key * to the requeue target futex so the waiter can detect the wakeup on the right * futex, but remove it from the hb and NULL the rt_waiter so it can detect |
beda2c7ea futex: Update fut... |
1645 1646 1647 |
* atomic lock acquisition. Set the q->lock_ptr to the requeue target hb->lock * to protect access to the pi_state to fixup the owner later. Must be called * with both q->lock_ptr and hb->lock held. |
52400ba94 futex: add requeu... |
1648 1649 |
*/ static inline |
beda2c7ea futex: Update fut... |
1650 1651 |
void requeue_pi_wake_futex(struct futex_q *q, union futex_key *key, struct futex_hash_bucket *hb) |
52400ba94 futex: add requeu... |
1652 |
{ |
52400ba94 futex: add requeu... |
1653 1654 |
get_futex_key_refs(key); q->key = *key; |
2e12978a9 futex,plist: Pass... |
1655 |
__unqueue_futex(q); |
52400ba94 futex: add requeu... |
1656 1657 1658 |
WARN_ON(!q->rt_waiter); q->rt_waiter = NULL; |
beda2c7ea futex: Update fut... |
1659 |
q->lock_ptr = &hb->lock; |
beda2c7ea futex: Update fut... |
1660 |
|
f1a11e057 futex: remove the... |
1661 |
wake_up_state(q->task, TASK_NORMAL); |
52400ba94 futex: add requeu... |
1662 1663 1664 1665 |
} /** * futex_proxy_trylock_atomic() - Attempt an atomic lock for the top waiter |
bab5bc9e8 futex: fixup unlo... |
1666 1667 1668 1669 1670 1671 1672 |
* @pifutex: the user address of the to futex * @hb1: the from futex hash bucket, must be locked by the caller * @hb2: the to futex hash bucket, must be locked by the caller * @key1: the from futex key * @key2: the to futex key * @ps: address to store the pi_state pointer * @set_waiters: force setting the FUTEX_WAITERS bit (1) or not (0) |
52400ba94 futex: add requeu... |
1673 1674 |
* * Try and get the lock on behalf of the top waiter if we can do it atomically. |
bab5bc9e8 futex: fixup unlo... |
1675 1676 1677 |
* Wake the top waiter if we succeed. If the caller specified set_waiters, * then direct futex_lock_pi_atomic() to force setting the FUTEX_WAITERS bit. * hb1 and hb2 must be held by the caller. |
52400ba94 futex: add requeu... |
1678 |
* |
6c23cbbd5 futex: fix kernel... |
1679 |
* Return: |
7b4ff1adb mutex, futex: adj... |
1680 1681 1682 |
* - 0 - failed to acquire the lock atomically; * - >0 - acquired the lock, return value is vpid of the top_waiter * - <0 - error |
52400ba94 futex: add requeu... |
1683 1684 1685 1686 1687 |
*/ static int futex_proxy_trylock_atomic(u32 __user *pifutex, struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2, union futex_key *key1, union futex_key *key2, |
bab5bc9e8 futex: fixup unlo... |
1688 |
struct futex_pi_state **ps, int set_waiters) |
52400ba94 futex: add requeu... |
1689 |
{ |
bab5bc9e8 futex: fixup unlo... |
1690 |
struct futex_q *top_waiter = NULL; |
52400ba94 futex: add requeu... |
1691 |
u32 curval; |
866293ee5 futex: Add anothe... |
1692 |
int ret, vpid; |
52400ba94 futex: add requeu... |
1693 1694 1695 |
if (get_futex_value_locked(&curval, pifutex)) return -EFAULT; |
ab51fbab3 futex: Fault/erro... |
1696 1697 |
if (unlikely(should_fail_futex(true))) return -EFAULT; |
bab5bc9e8 futex: fixup unlo... |
1698 1699 1700 1701 1702 1703 1704 1705 |
/* * Find the top_waiter and determine if there are additional waiters. * If the caller intends to requeue more than 1 waiter to pifutex, * force futex_lock_pi_atomic() to set the FUTEX_WAITERS bit now, * as we have means to handle the possible fault. If not, don't set * the bit unecessarily as it will force the subsequent unlock to enter * the kernel. */ |
52400ba94 futex: add requeu... |
1706 1707 1708 1709 1710 |
top_waiter = futex_top_waiter(hb1, key1); /* There are no waiters, nothing for us to do. */ if (!top_waiter) return 0; |
84bc4af59 futex: Detect mis... |
1711 1712 1713 |
/* Ensure we requeue to the expected futex. */ if (!match_futex(top_waiter->requeue_pi_key, key2)) return -EINVAL; |
52400ba94 futex: add requeu... |
1714 |
/* |
bab5bc9e8 futex: fixup unlo... |
1715 1716 1717 |
* Try to take the lock for top_waiter. Set the FUTEX_WAITERS bit in * the contended case or if set_waiters is 1. The pi_state is returned * in ps in contended cases. |
52400ba94 futex: add requeu... |
1718 |
*/ |
866293ee5 futex: Add anothe... |
1719 |
vpid = task_pid_vnr(top_waiter->task); |
bab5bc9e8 futex: fixup unlo... |
1720 1721 |
ret = futex_lock_pi_atomic(pifutex, hb2, key2, ps, top_waiter->task, set_waiters); |
866293ee5 futex: Add anothe... |
1722 |
if (ret == 1) { |
beda2c7ea futex: Update fut... |
1723 |
requeue_pi_wake_futex(top_waiter, key2, hb2); |
866293ee5 futex: Add anothe... |
1724 1725 |
return vpid; } |
52400ba94 futex: add requeu... |
1726 1727 1728 1729 1730 |
return ret; } /** * futex_requeue() - Requeue waiters from uaddr1 to uaddr2 |
fb62db2ba futex: Fix kernel... |
1731 |
* @uaddr1: source futex user address |
b41277dc7 futex: Replace fs... |
1732 |
* @flags: futex flags (FLAGS_SHARED, etc.) |
fb62db2ba futex: Fix kernel... |
1733 1734 1735 1736 1737 |
* @uaddr2: target futex user address * @nr_wake: number of waiters to wake (must be 1 for requeue_pi) * @nr_requeue: number of waiters to requeue (0-INT_MAX) * @cmpval: @uaddr1 expected value (or %NULL) * @requeue_pi: if we are attempting to requeue from a non-pi futex to a |
b41277dc7 futex: Replace fs... |
1738 |
* pi futex (pi to pi requeue is not supported) |
52400ba94 futex: add requeu... |
1739 1740 1741 1742 |
* * Requeue waiters on uaddr1 to uaddr2. In the requeue_pi case, try to acquire * uaddr2 atomically on behalf of the top waiter. * |
6c23cbbd5 futex: fix kernel... |
1743 |
* Return: |
7b4ff1adb mutex, futex: adj... |
1744 1745 |
* - >=0 - on success, the number of tasks requeued or woken; * - <0 - on error |
1da177e4c Linux-2.6.12-rc2 |
1746 |
*/ |
b41277dc7 futex: Replace fs... |
1747 1748 1749 |
static int futex_requeue(u32 __user *uaddr1, unsigned int flags, u32 __user *uaddr2, int nr_wake, int nr_requeue, u32 *cmpval, int requeue_pi) |
1da177e4c Linux-2.6.12-rc2 |
1750 |
{ |
38d47c1b7 futex: rely on ge... |
1751 |
union futex_key key1 = FUTEX_KEY_INIT, key2 = FUTEX_KEY_INIT; |
52400ba94 futex: add requeu... |
1752 1753 |
int drop_count = 0, task_count = 0, ret; struct futex_pi_state *pi_state = NULL; |
e2970f2fb [PATCH] pi-futex:... |
1754 |
struct futex_hash_bucket *hb1, *hb2; |
1da177e4c Linux-2.6.12-rc2 |
1755 |
struct futex_q *this, *next; |
194a6b5b9 sched/wake_q: Ren... |
1756 |
DEFINE_WAKE_Q(wake_q); |
52400ba94 futex: add requeu... |
1757 |
|
bc2eecd7e futex: Allow for ... |
1758 1759 1760 1761 1762 1763 1764 1765 |
/* * When PI not supported: return -ENOSYS if requeue_pi is true, * consequently the compiler knows requeue_pi is always false past * this point which will optimize away all the conditional code * further down. */ if (!IS_ENABLED(CONFIG_FUTEX_PI) && requeue_pi) return -ENOSYS; |
52400ba94 futex: add requeu... |
1766 1767 |
if (requeue_pi) { /* |
e9c243a5a futex-prevent-req... |
1768 1769 1770 1771 1772 1773 1774 |
* Requeue PI only works on two distinct uaddrs. This * check is only valid for private futexes. See below. */ if (uaddr1 == uaddr2) return -EINVAL; /* |
52400ba94 futex: add requeu... |
1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 |
* requeue_pi requires a pi_state, try to allocate it now * without any locks in case it fails. */ if (refill_pi_state_cache()) return -ENOMEM; /* * requeue_pi must wake as many tasks as it can, up to nr_wake * + nr_requeue, since it acquires the rt_mutex prior to * returning to userspace, so as to not leave the rt_mutex with * waiters and no owner. However, second and third wake-ups * cannot be predicted as they involve race conditions with the * first wake and a fault while looking up the pi_state. Both * pthread_cond_signal() and pthread_cond_broadcast() should * use nr_wake=1. */ if (nr_wake != 1) return -EINVAL; } |
1da177e4c Linux-2.6.12-rc2 |
1793 |
|
42d35d48c futex: make futex... |
1794 |
retry: |
9ea71503a futex: Fix regres... |
1795 |
ret = get_futex_key(uaddr1, flags & FLAGS_SHARED, &key1, VERIFY_READ); |
1da177e4c Linux-2.6.12-rc2 |
1796 1797 |
if (unlikely(ret != 0)) goto out; |
9ea71503a futex: Fix regres... |
1798 1799 |
ret = get_futex_key(uaddr2, flags & FLAGS_SHARED, &key2, requeue_pi ? VERIFY_WRITE : VERIFY_READ); |
1da177e4c Linux-2.6.12-rc2 |
1800 |
if (unlikely(ret != 0)) |
42d35d48c futex: make futex... |
1801 |
goto out_put_key1; |
1da177e4c Linux-2.6.12-rc2 |
1802 |
|
e9c243a5a futex-prevent-req... |
1803 1804 1805 1806 1807 1808 1809 1810 |
/* * The check above which compares uaddrs is not sufficient for * shared futexes. We need to compare the keys: */ if (requeue_pi && match_futex(&key1, &key2)) { ret = -EINVAL; goto out_put_keys; } |
e2970f2fb [PATCH] pi-futex:... |
1811 1812 |
hb1 = hash_futex(&key1); hb2 = hash_futex(&key2); |
1da177e4c Linux-2.6.12-rc2 |
1813 |
|
e4dc5b7a3 futex: clean up f... |
1814 |
retry_private: |
69cd9eba3 futex: avoid race... |
1815 |
hb_waiters_inc(hb2); |
8b8f319fc [PATCH] lockdep: ... |
1816 |
double_lock_hb(hb1, hb2); |
1da177e4c Linux-2.6.12-rc2 |
1817 |
|
e2970f2fb [PATCH] pi-futex:... |
1818 1819 |
if (likely(cmpval != NULL)) { u32 curval; |
1da177e4c Linux-2.6.12-rc2 |
1820 |
|
e2970f2fb [PATCH] pi-futex:... |
1821 |
ret = get_futex_value_locked(&curval, uaddr1); |
1da177e4c Linux-2.6.12-rc2 |
1822 1823 |
if (unlikely(ret)) { |
5eb3dc62f futex: add double... |
1824 |
double_unlock_hb(hb1, hb2); |
69cd9eba3 futex: avoid race... |
1825 |
hb_waiters_dec(hb2); |
1da177e4c Linux-2.6.12-rc2 |
1826 |
|
e2970f2fb [PATCH] pi-futex:... |
1827 |
ret = get_user(curval, uaddr1); |
e4dc5b7a3 futex: clean up f... |
1828 1829 |
if (ret) goto out_put_keys; |
1da177e4c Linux-2.6.12-rc2 |
1830 |
|
b41277dc7 futex: Replace fs... |
1831 |
if (!(flags & FLAGS_SHARED)) |
e4dc5b7a3 futex: clean up f... |
1832 |
goto retry_private; |
1da177e4c Linux-2.6.12-rc2 |
1833 |
|
ae791a2d2 futex: Cleanup st... |
1834 1835 |
put_futex_key(&key2); put_futex_key(&key1); |
e4dc5b7a3 futex: clean up f... |
1836 |
goto retry; |
1da177e4c Linux-2.6.12-rc2 |
1837 |
} |
e2970f2fb [PATCH] pi-futex:... |
1838 |
if (curval != *cmpval) { |
1da177e4c Linux-2.6.12-rc2 |
1839 1840 1841 1842 |
ret = -EAGAIN; goto out_unlock; } } |
52400ba94 futex: add requeu... |
1843 |
if (requeue_pi && (task_count - nr_wake < nr_requeue)) { |
bab5bc9e8 futex: fixup unlo... |
1844 1845 1846 1847 1848 1849 |
/* * Attempt to acquire uaddr2 and wake the top waiter. If we * intend to requeue waiters, force setting the FUTEX_WAITERS * bit. We force this here where we are able to easily handle * faults rather in the requeue loop below. */ |
52400ba94 futex: add requeu... |
1850 |
ret = futex_proxy_trylock_atomic(uaddr2, hb1, hb2, &key1, |
bab5bc9e8 futex: fixup unlo... |
1851 |
&key2, &pi_state, nr_requeue); |
52400ba94 futex: add requeu... |
1852 1853 1854 1855 1856 |
/* * At this point the top_waiter has either taken uaddr2 or is * waiting on it. If the former, then the pi_state will not * exist yet, look it up one more time to ensure we have a |
866293ee5 futex: Add anothe... |
1857 1858 |
* reference to it. If the lock was taken, ret contains the * vpid of the top waiter task. |
ecb38b78f futex: Document p... |
1859 1860 |
* If the lock was not taken, we have pi_state and an initial * refcount on it. In case of an error we have nothing. |
52400ba94 futex: add requeu... |
1861 |
*/ |
866293ee5 futex: Add anothe... |
1862 |
if (ret > 0) { |
52400ba94 futex: add requeu... |
1863 |
WARN_ON(pi_state); |
89061d3d5 futex: Move drop_... |
1864 |
drop_count++; |
52400ba94 futex: add requeu... |
1865 |
task_count++; |
866293ee5 futex: Add anothe... |
1866 |
/* |
ecb38b78f futex: Document p... |
1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 |
* If we acquired the lock, then the user space value * of uaddr2 should be vpid. It cannot be changed by * the top waiter as it is blocked on hb2 lock if it * tries to do so. If something fiddled with it behind * our back the pi state lookup might unearth it. So * we rather use the known value than rereading and * handing potential crap to lookup_pi_state. * * If that call succeeds then we have pi_state and an * initial refcount on it. |
866293ee5 futex: Add anothe... |
1877 |
*/ |
734009e96 futex: Change loc... |
1878 |
ret = lookup_pi_state(uaddr2, ret, hb2, &key2, &pi_state); |
52400ba94 futex: add requeu... |
1879 1880 1881 1882 |
} switch (ret) { case 0: |
ecb38b78f futex: Document p... |
1883 |
/* We hold a reference on the pi state. */ |
52400ba94 futex: add requeu... |
1884 |
break; |
4959f2de1 futex: Remove poi... |
1885 1886 |
/* If the above failed, then pi_state is NULL */ |
52400ba94 futex: add requeu... |
1887 1888 |
case -EFAULT: double_unlock_hb(hb1, hb2); |
69cd9eba3 futex: avoid race... |
1889 |
hb_waiters_dec(hb2); |
ae791a2d2 futex: Cleanup st... |
1890 1891 |
put_futex_key(&key2); put_futex_key(&key1); |
d0725992c futex: Fix the wr... |
1892 |
ret = fault_in_user_writeable(uaddr2); |
52400ba94 futex: add requeu... |
1893 1894 1895 1896 |
if (!ret) goto retry; goto out; case -EAGAIN: |
af54d6a1c futex: Simplify f... |
1897 1898 1899 1900 1901 1902 |
/* * Two reasons for this: * - Owner is exiting and we just wait for the * exit to complete. * - The user space value changed. */ |
52400ba94 futex: add requeu... |
1903 |
double_unlock_hb(hb1, hb2); |
69cd9eba3 futex: avoid race... |
1904 |
hb_waiters_dec(hb2); |
ae791a2d2 futex: Cleanup st... |
1905 1906 |
put_futex_key(&key2); put_futex_key(&key1); |
52400ba94 futex: add requeu... |
1907 1908 1909 1910 1911 1912 |
cond_resched(); goto retry; default: goto out_unlock; } } |
0d00c7b20 futexes: Clean up... |
1913 |
plist_for_each_entry_safe(this, next, &hb1->chain, list) { |
52400ba94 futex: add requeu... |
1914 1915 1916 1917 |
if (task_count - nr_wake >= nr_requeue) break; if (!match_futex(&this->key, &key1)) |
1da177e4c Linux-2.6.12-rc2 |
1918 |
continue; |
52400ba94 futex: add requeu... |
1919 |
|
392741e0a futex: Fix handli... |
1920 1921 1922 |
/* * FUTEX_WAIT_REQEUE_PI and FUTEX_CMP_REQUEUE_PI should always * be paired with each other and no other futex ops. |
aa10990e0 futex: avoid wake... |
1923 1924 1925 |
* * We should never be requeueing a futex_q with a pi_state, * which is awaiting a futex_unlock_pi(). |
392741e0a futex: Fix handli... |
1926 1927 |
*/ if ((requeue_pi && !this->rt_waiter) || |
aa10990e0 futex: avoid wake... |
1928 1929 |
(!requeue_pi && this->rt_waiter) || this->pi_state) { |
392741e0a futex: Fix handli... |
1930 1931 1932 |
ret = -EINVAL; break; } |
52400ba94 futex: add requeu... |
1933 1934 1935 1936 1937 1938 1939 |
/* * Wake nr_wake waiters. For requeue_pi, if we acquired the * lock, we already woke the top_waiter. If not, it will be * woken by futex_unlock_pi(). */ if (++task_count <= nr_wake && !requeue_pi) { |
1d0dcb3ad futex: Implement ... |
1940 |
mark_wake_futex(&wake_q, this); |
52400ba94 futex: add requeu... |
1941 1942 |
continue; } |
1da177e4c Linux-2.6.12-rc2 |
1943 |
|
84bc4af59 futex: Detect mis... |
1944 1945 1946 1947 1948 |
/* Ensure we requeue to the expected futex for requeue_pi. */ if (requeue_pi && !match_futex(this->requeue_pi_key, &key2)) { ret = -EINVAL; break; } |
52400ba94 futex: add requeu... |
1949 1950 1951 1952 1953 |
/* * Requeue nr_requeue waiters and possibly one more in the case * of requeue_pi if we couldn't acquire the lock atomically. */ if (requeue_pi) { |
ecb38b78f futex: Document p... |
1954 1955 1956 1957 1958 |
/* * Prepare the waiter to take the rt_mutex. Take a * refcount on the pi_state and store the pointer in * the futex_q object of the waiter. */ |
bf92cf3a5 futex: Cleanup re... |
1959 |
get_pi_state(pi_state); |
52400ba94 futex: add requeu... |
1960 1961 1962 |
this->pi_state = pi_state; ret = rt_mutex_start_proxy_lock(&pi_state->pi_mutex, this->rt_waiter, |
c051b21f7 rtmutex: Confine ... |
1963 |
this->task); |
52400ba94 futex: add requeu... |
1964 |
if (ret == 1) { |
ecb38b78f futex: Document p... |
1965 1966 1967 1968 1969 1970 1971 1972 |
/* * We got the lock. We do neither drop the * refcount on pi_state nor clear * this->pi_state because the waiter needs the * pi_state for cleaning up the user space * value. It will drop the refcount after * doing so. */ |
beda2c7ea futex: Update fut... |
1973 |
requeue_pi_wake_futex(this, &key2, hb2); |
89061d3d5 futex: Move drop_... |
1974 |
drop_count++; |
52400ba94 futex: add requeu... |
1975 1976 |
continue; } else if (ret) { |
ecb38b78f futex: Document p... |
1977 1978 1979 1980 1981 1982 1983 1984 |
/* * rt_mutex_start_proxy_lock() detected a * potential deadlock when we tried to queue * that waiter. Drop the pi_state reference * which we took above and remove the pointer * to the state from the waiters futex_q * object. */ |
52400ba94 futex: add requeu... |
1985 |
this->pi_state = NULL; |
29e9ee5d4 futex: Rename fre... |
1986 |
put_pi_state(pi_state); |
885c2cb77 futex: Cleanup th... |
1987 1988 1989 1990 1991 |
/* * We stop queueing more waiters and let user * space deal with the mess. */ break; |
52400ba94 futex: add requeu... |
1992 |
} |
1da177e4c Linux-2.6.12-rc2 |
1993 |
} |
52400ba94 futex: add requeu... |
1994 1995 |
requeue_futex(this, hb1, hb2, &key2); drop_count++; |
1da177e4c Linux-2.6.12-rc2 |
1996 |
} |
ecb38b78f futex: Document p... |
1997 1998 1999 2000 2001 |
/* * We took an extra initial reference to the pi_state either * in futex_proxy_trylock_atomic() or in lookup_pi_state(). We * need to drop it here again. */ |
29e9ee5d4 futex: Rename fre... |
2002 |
put_pi_state(pi_state); |
885c2cb77 futex: Cleanup th... |
2003 2004 |
out_unlock: |
5eb3dc62f futex: add double... |
2005 |
double_unlock_hb(hb1, hb2); |
1d0dcb3ad futex: Implement ... |
2006 |
wake_up_q(&wake_q); |
69cd9eba3 futex: avoid race... |
2007 |
hb_waiters_dec(hb2); |
1da177e4c Linux-2.6.12-rc2 |
2008 |
|
cd84a42f3 futex: comment re... |
2009 2010 2011 2012 2013 2014 |
/* * drop_futex_key_refs() must be called outside the spinlocks. During * the requeue we moved futex_q's from the hash bucket at key1 to the * one at key2 and updated their key pointer. We no longer need to * hold the references to key1. */ |
1da177e4c Linux-2.6.12-rc2 |
2015 |
while (--drop_count >= 0) |
9adef58b1 futex: get_futex_... |
2016 |
drop_futex_key_refs(&key1); |
1da177e4c Linux-2.6.12-rc2 |
2017 |
|
42d35d48c futex: make futex... |
2018 |
out_put_keys: |
ae791a2d2 futex: Cleanup st... |
2019 |
put_futex_key(&key2); |
42d35d48c futex: make futex... |
2020 |
out_put_key1: |
ae791a2d2 futex: Cleanup st... |
2021 |
put_futex_key(&key1); |
42d35d48c futex: make futex... |
2022 |
out: |
52400ba94 futex: add requeu... |
2023 |
return ret ? ret : task_count; |
1da177e4c Linux-2.6.12-rc2 |
2024 2025 2026 |
} /* The key must be already stored in q->key. */ |
82af7aca5 Removal of FUTEX_FD |
2027 |
static inline struct futex_hash_bucket *queue_lock(struct futex_q *q) |
15e408cd6 futex: Add lock c... |
2028 |
__acquires(&hb->lock) |
1da177e4c Linux-2.6.12-rc2 |
2029 |
{ |
e2970f2fb [PATCH] pi-futex:... |
2030 |
struct futex_hash_bucket *hb; |
1da177e4c Linux-2.6.12-rc2 |
2031 |
|
e2970f2fb [PATCH] pi-futex:... |
2032 |
hb = hash_futex(&q->key); |
11d4616bd futex: revert bac... |
2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 |
/* * Increment the counter before taking the lock so that * a potential waker won't miss a to-be-slept task that is * waiting for the spinlock. This is safe as all queue_lock() * users end up calling queue_me(). Similarly, for housekeeping, * decrement the counter at queue_unlock() when some error has * occurred and we don't end up adding the task to the list. */ hb_waiters_inc(hb); |
e2970f2fb [PATCH] pi-futex:... |
2043 |
q->lock_ptr = &hb->lock; |
1da177e4c Linux-2.6.12-rc2 |
2044 |
|
8ad7b378d futex: Rename bar... |
2045 |
spin_lock(&hb->lock); /* implies smp_mb(); (A) */ |
e2970f2fb [PATCH] pi-futex:... |
2046 |
return hb; |
1da177e4c Linux-2.6.12-rc2 |
2047 |
} |
d40d65c8d futex: Correct qu... |
2048 |
static inline void |
0d00c7b20 futexes: Clean up... |
2049 |
queue_unlock(struct futex_hash_bucket *hb) |
15e408cd6 futex: Add lock c... |
2050 |
__releases(&hb->lock) |
d40d65c8d futex: Correct qu... |
2051 2052 |
{ spin_unlock(&hb->lock); |
11d4616bd futex: revert bac... |
2053 |
hb_waiters_dec(hb); |
d40d65c8d futex: Correct qu... |
2054 |
} |
cfafcd117 futex: Rework fut... |
2055 |
static inline void __queue_me(struct futex_q *q, struct futex_hash_bucket *hb) |
1da177e4c Linux-2.6.12-rc2 |
2056 |
{ |
ec92d0829 futex priority ba... |
2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 |
int prio; /* * The priority used to register this element is * - either the real thread-priority for the real-time threads * (i.e. threads with a priority lower than MAX_RT_PRIO) * - or MAX_RT_PRIO for non-RT threads. * Thus, all RT-threads are woken first in priority order, and * the others are woken last, in FIFO order. */ prio = min(current->normal_prio, MAX_RT_PRIO); plist_node_init(&q->list, prio); |
ec92d0829 futex priority ba... |
2070 |
plist_add(&q->list, &hb->chain); |
c87e2837b [PATCH] pi-futex:... |
2071 |
q->task = current; |
cfafcd117 futex: Rework fut... |
2072 2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 |
} /** * queue_me() - Enqueue the futex_q on the futex_hash_bucket * @q: The futex_q to enqueue * @hb: The destination hash bucket * * The hb->lock must be held by the caller, and is released here. A call to * queue_me() is typically paired with exactly one call to unqueue_me(). The * exceptions involve the PI related operations, which may use unqueue_me_pi() * or nothing if the unqueue is done as part of the wake process and the unqueue * state is implicit in the state of woken task (see futex_wait_requeue_pi() for * an example). */ static inline void queue_me(struct futex_q *q, struct futex_hash_bucket *hb) __releases(&hb->lock) { __queue_me(q, hb); |
e2970f2fb [PATCH] pi-futex:... |
2090 |
spin_unlock(&hb->lock); |
1da177e4c Linux-2.6.12-rc2 |
2091 |
} |
d40d65c8d futex: Correct qu... |
2092 2093 2094 2095 2096 2097 2098 |
/** * unqueue_me() - Remove the futex_q from its futex_hash_bucket * @q: The futex_q to unqueue * * The q->lock_ptr must not be held by the caller. A call to unqueue_me() must * be paired with exactly one earlier call to queue_me(). * |
6c23cbbd5 futex: fix kernel... |
2099 |
* Return: |
7b4ff1adb mutex, futex: adj... |
2100 2101 |
* - 1 - if the futex_q was still queued (and we removed unqueued it); * - 0 - if the futex_q was already removed by the waking thread |
1da177e4c Linux-2.6.12-rc2 |
2102 |
*/ |
1da177e4c Linux-2.6.12-rc2 |
2103 2104 |
static int unqueue_me(struct futex_q *q) { |
1da177e4c Linux-2.6.12-rc2 |
2105 |
spinlock_t *lock_ptr; |
e2970f2fb [PATCH] pi-futex:... |
2106 |
int ret = 0; |
1da177e4c Linux-2.6.12-rc2 |
2107 2108 |
/* In the common case we don't take the spinlock, which is nice. */ |
42d35d48c futex: make futex... |
2109 |
retry: |
29b75eb2d futex: Replace ba... |
2110 2111 2112 2113 2114 2115 |
/* * q->lock_ptr can change between this read and the following spin_lock. * Use READ_ONCE to forbid the compiler from reloading q->lock_ptr and * optimizing lock_ptr out of the logic below. */ lock_ptr = READ_ONCE(q->lock_ptr); |
c80544dc0 sparse pointer us... |
2116 |
if (lock_ptr != NULL) { |
1da177e4c Linux-2.6.12-rc2 |
2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 |
spin_lock(lock_ptr); /* * q->lock_ptr can change between reading it and * spin_lock(), causing us to take the wrong lock. This * corrects the race condition. * * Reasoning goes like this: if we have the wrong lock, * q->lock_ptr must have changed (maybe several times) * between reading it and the spin_lock(). It can * change again after the spin_lock() but only if it was * already changed before the spin_lock(). It cannot, * however, change back to the original value. Therefore * we can detect whether we acquired the correct lock. */ if (unlikely(lock_ptr != q->lock_ptr)) { spin_unlock(lock_ptr); goto retry; } |
2e12978a9 futex,plist: Pass... |
2135 |
__unqueue_futex(q); |
c87e2837b [PATCH] pi-futex:... |
2136 2137 |
BUG_ON(q->pi_state); |
1da177e4c Linux-2.6.12-rc2 |
2138 2139 2140 |
spin_unlock(lock_ptr); ret = 1; } |
9adef58b1 futex: get_futex_... |
2141 |
drop_futex_key_refs(&q->key); |
1da177e4c Linux-2.6.12-rc2 |
2142 2143 |
return ret; } |
c87e2837b [PATCH] pi-futex:... |
2144 2145 |
/* * PI futexes can not be requeued and must remove themself from the |
d0aa7a70b futex_requeue_pi ... |
2146 2147 |
* hash bucket. The hash bucket lock (i.e. lock_ptr) is held on entry * and dropped here. |
c87e2837b [PATCH] pi-futex:... |
2148 |
*/ |
d0aa7a70b futex_requeue_pi ... |
2149 |
static void unqueue_me_pi(struct futex_q *q) |
15e408cd6 futex: Add lock c... |
2150 |
__releases(q->lock_ptr) |
c87e2837b [PATCH] pi-futex:... |
2151 |
{ |
2e12978a9 futex,plist: Pass... |
2152 |
__unqueue_futex(q); |
c87e2837b [PATCH] pi-futex:... |
2153 2154 |
BUG_ON(!q->pi_state); |
29e9ee5d4 futex: Rename fre... |
2155 |
put_pi_state(q->pi_state); |
c87e2837b [PATCH] pi-futex:... |
2156 |
q->pi_state = NULL; |
d0aa7a70b futex_requeue_pi ... |
2157 |
spin_unlock(q->lock_ptr); |
c87e2837b [PATCH] pi-futex:... |
2158 |
} |
d0aa7a70b futex_requeue_pi ... |
2159 |
/* |
cdf71a10c futex: Prevent st... |
2160 |
* Fixup the pi_state owner with the new owner. |
d0aa7a70b futex_requeue_pi ... |
2161 |
* |
778e9a9c3 pi-futex: fix exi... |
2162 2163 |
* Must be called with hash bucket lock held and mm->sem held for non * private futexes. |
d0aa7a70b futex_requeue_pi ... |
2164 |
*/ |
778e9a9c3 pi-futex: fix exi... |
2165 |
static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q, |
ae791a2d2 futex: Cleanup st... |
2166 |
struct task_struct *newowner) |
d0aa7a70b futex_requeue_pi ... |
2167 |
{ |
cdf71a10c futex: Prevent st... |
2168 |
u32 newtid = task_pid_vnr(newowner) | FUTEX_WAITERS; |
d0aa7a70b futex_requeue_pi ... |
2169 |
struct futex_pi_state *pi_state = q->pi_state; |
7cfdaf38d futex: uninitiali... |
2170 |
u32 uval, uninitialized_var(curval), newval; |
734009e96 futex: Change loc... |
2171 |
struct task_struct *oldowner; |
e4dc5b7a3 futex: clean up f... |
2172 |
int ret; |
d0aa7a70b futex_requeue_pi ... |
2173 |
|
734009e96 futex: Change loc... |
2174 2175 2176 |
raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock); oldowner = pi_state->owner; |
d0aa7a70b futex_requeue_pi ... |
2177 |
/* Owner died? */ |
1b7558e45 futexes: fix faul... |
2178 2179 2180 2181 2182 |
if (!pi_state->owner) newtid |= FUTEX_OWNER_DIED; /* * We are here either because we stole the rtmutex from the |
8161239a8 rtmutex: Simplify... |
2183 |
* previous highest priority waiter or we are the highest priority |
16ffa12d7 futex: Pull rt_mu... |
2184 2185 |
* waiter but have failed to get the rtmutex the first time. * |
8161239a8 rtmutex: Simplify... |
2186 2187 |
* We have to replace the newowner TID in the user space variable. * This must be atomic as we have to preserve the owner died bit here. |
1b7558e45 futexes: fix faul... |
2188 |
* |
b2d0994b1 futex: update fut... |
2189 2190 2191 |
* Note: We write the user space value _before_ changing the pi_state * because we can fault here. Imagine swapped out pages or a fork * that marked all the anonymous memory readonly for cow. |
1b7558e45 futexes: fix faul... |
2192 |
* |
734009e96 futex: Change loc... |
2193 2194 2195 2196 |
* Modifying pi_state _before_ the user space value would leave the * pi_state in an inconsistent state when we fault here, because we * need to drop the locks to handle the fault. This might be observed * in the PID check in lookup_pi_state. |
1b7558e45 futexes: fix faul... |
2197 2198 2199 2200 |
*/ retry: if (get_futex_value_locked(&uval, uaddr)) goto handle_fault; |
16ffa12d7 futex: Pull rt_mu... |
2201 |
for (;;) { |
1b7558e45 futexes: fix faul... |
2202 |
newval = (uval & FUTEX_OWNER_DIED) | newtid; |
37a9d912b futex: Sanitize c... |
2203 |
if (cmpxchg_futex_value_locked(&curval, uaddr, uval, newval)) |
1b7558e45 futexes: fix faul... |
2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 |
goto handle_fault; if (curval == uval) break; uval = curval; } /* * We fixed up user space. Now we need to fix the pi_state * itself. */ |
d0aa7a70b futex_requeue_pi ... |
2214 |
if (pi_state->owner != NULL) { |
734009e96 futex: Change loc... |
2215 |
raw_spin_lock(&pi_state->owner->pi_lock); |
d0aa7a70b futex_requeue_pi ... |
2216 2217 |
WARN_ON(list_empty(&pi_state->list)); list_del_init(&pi_state->list); |
734009e96 futex: Change loc... |
2218 |
raw_spin_unlock(&pi_state->owner->pi_lock); |
1b7558e45 futexes: fix faul... |
2219 |
} |
d0aa7a70b futex_requeue_pi ... |
2220 |
|
cdf71a10c futex: Prevent st... |
2221 |
pi_state->owner = newowner; |
d0aa7a70b futex_requeue_pi ... |
2222 |
|
734009e96 futex: Change loc... |
2223 |
raw_spin_lock(&newowner->pi_lock); |
d0aa7a70b futex_requeue_pi ... |
2224 |
WARN_ON(!list_empty(&pi_state->list)); |
cdf71a10c futex: Prevent st... |
2225 |
list_add(&pi_state->list, &newowner->pi_state_list); |
734009e96 futex: Change loc... |
2226 2227 |
raw_spin_unlock(&newowner->pi_lock); raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock); |
1b7558e45 futexes: fix faul... |
2228 |
return 0; |
d0aa7a70b futex_requeue_pi ... |
2229 |
|
d0aa7a70b futex_requeue_pi ... |
2230 |
/* |
734009e96 futex: Change loc... |
2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 |
* To handle the page fault we need to drop the locks here. That gives * the other task (either the highest priority waiter itself or the * task which stole the rtmutex) the chance to try the fixup of the * pi_state. So once we are back from handling the fault we need to * check the pi_state after reacquiring the locks and before trying to * do another fixup. When the fixup has been done already we simply * return. * * Note: we hold both hb->lock and pi_mutex->wait_lock. We can safely * drop hb->lock since the caller owns the hb -> futex_q relation. * Dropping the pi_mutex->wait_lock requires the state revalidate. |
d0aa7a70b futex_requeue_pi ... |
2242 |
*/ |
1b7558e45 futexes: fix faul... |
2243 |
handle_fault: |
734009e96 futex: Change loc... |
2244 |
raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock); |
1b7558e45 futexes: fix faul... |
2245 |
spin_unlock(q->lock_ptr); |
778e9a9c3 pi-futex: fix exi... |
2246 |
|
d0725992c futex: Fix the wr... |
2247 |
ret = fault_in_user_writeable(uaddr); |
778e9a9c3 pi-futex: fix exi... |
2248 |
|
1b7558e45 futexes: fix faul... |
2249 |
spin_lock(q->lock_ptr); |
734009e96 futex: Change loc... |
2250 |
raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock); |
778e9a9c3 pi-futex: fix exi... |
2251 |
|
1b7558e45 futexes: fix faul... |
2252 2253 2254 |
/* * Check if someone else fixed it for us: */ |
734009e96 futex: Change loc... |
2255 2256 2257 2258 |
if (pi_state->owner != oldowner) { ret = 0; goto out_unlock; } |
1b7558e45 futexes: fix faul... |
2259 2260 |
if (ret) |
734009e96 futex: Change loc... |
2261 |
goto out_unlock; |
1b7558e45 futexes: fix faul... |
2262 2263 |
goto retry; |
734009e96 futex: Change loc... |
2264 2265 2266 2267 |
out_unlock: raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock); return ret; |
d0aa7a70b futex_requeue_pi ... |
2268 |
} |
72c1bbf30 futex: restartabl... |
2269 |
static long futex_wait_restart(struct restart_block *restart); |
36cf3b5c3 FUTEX: Tidy up th... |
2270 |
|
ca5f9524d futex: separate f... |
2271 |
/** |
dd9739980 futex: split out ... |
2272 2273 |
* fixup_owner() - Post lock pi_state and corner case management * @uaddr: user address of the futex |
dd9739980 futex: split out ... |
2274 2275 2276 2277 2278 2279 2280 |
* @q: futex_q (contains pi_state and access to the rt_mutex) * @locked: if the attempt to take the rt_mutex succeeded (1) or not (0) * * After attempting to lock an rt_mutex, this function is called to cleanup * the pi_state owner as well as handle race conditions that may allow us to * acquire the lock. Must be called with the hb lock held. * |
6c23cbbd5 futex: fix kernel... |
2281 |
* Return: |
7b4ff1adb mutex, futex: adj... |
2282 2283 2284 |
* - 1 - success, lock taken; * - 0 - success, lock not taken; * - <0 - on error (-EFAULT) |
dd9739980 futex: split out ... |
2285 |
*/ |
ae791a2d2 futex: Cleanup st... |
2286 |
static int fixup_owner(u32 __user *uaddr, struct futex_q *q, int locked) |
dd9739980 futex: split out ... |
2287 |
{ |
dd9739980 futex: split out ... |
2288 2289 2290 2291 2292 2293 |
int ret = 0; if (locked) { /* * Got the lock. We might not be the anticipated owner if we * did a lock-steal - fix up the PI-state in that case: |
16ffa12d7 futex: Pull rt_mu... |
2294 2295 2296 2297 |
* * We can safely read pi_state->owner without holding wait_lock * because we now own the rt_mutex, only the owner will attempt * to change it. |
dd9739980 futex: split out ... |
2298 2299 |
*/ if (q->pi_state->owner != current) |
ae791a2d2 futex: Cleanup st... |
2300 |
ret = fixup_pi_state_owner(uaddr, q, current); |
dd9739980 futex: split out ... |
2301 2302 2303 2304 |
goto out; } /* |
dd9739980 futex: split out ... |
2305 |
* Paranoia check. If we did not take the lock, then we should not be |
8161239a8 rtmutex: Simplify... |
2306 |
* the owner of the rt_mutex. |
dd9739980 futex: split out ... |
2307 |
*/ |
73d786bd0 futex: Rework inc... |
2308 |
if (rt_mutex_owner(&q->pi_state->pi_mutex) == current) { |
dd9739980 futex: split out ... |
2309 2310 2311 2312 2313 |
printk(KERN_ERR "fixup_owner: ret = %d pi-mutex: %p " "pi-state %p ", ret, q->pi_state->pi_mutex.owner, q->pi_state->owner); |
73d786bd0 futex: Rework inc... |
2314 |
} |
dd9739980 futex: split out ... |
2315 2316 2317 2318 2319 2320 |
out: return ret ? ret : locked; } /** |
ca5f9524d futex: separate f... |
2321 2322 2323 2324 |
* futex_wait_queue_me() - queue_me() and wait for wakeup, timeout, or signal * @hb: the futex hash bucket, must be locked by the caller * @q: the futex_q to queue up on * @timeout: the prepared hrtimer_sleeper, or null for no timeout |
ca5f9524d futex: separate f... |
2325 2326 |
*/ static void futex_wait_queue_me(struct futex_hash_bucket *hb, struct futex_q *q, |
f1a11e057 futex: remove the... |
2327 |
struct hrtimer_sleeper *timeout) |
ca5f9524d futex: separate f... |
2328 |
{ |
9beba3c54 futex: Add memory... |
2329 2330 |
/* * The task state is guaranteed to be set before another task can |
b92b8b35a locking/arch: Ren... |
2331 |
* wake it. set_current_state() is implemented using smp_store_mb() and |
9beba3c54 futex: Add memory... |
2332 2333 2334 |
* queue_me() calls spin_unlock() upon completion, both serializing * access to the hash list and forcing another memory barrier. */ |
f1a11e057 futex: remove the... |
2335 |
set_current_state(TASK_INTERRUPTIBLE); |
0729e1961 futex: Fix wakeup... |
2336 |
queue_me(q, hb); |
ca5f9524d futex: separate f... |
2337 2338 |
/* Arm the timer */ |
2e4b0d3fe futex: Remove bog... |
2339 |
if (timeout) |
ca5f9524d futex: separate f... |
2340 |
hrtimer_start_expires(&timeout->timer, HRTIMER_MODE_ABS); |
ca5f9524d futex: separate f... |
2341 2342 |
/* |
0729e1961 futex: Fix wakeup... |
2343 2344 |
* If we have been removed from the hash list, then another task * has tried to wake us, and we can skip the call to schedule(). |
ca5f9524d futex: separate f... |
2345 2346 2347 2348 2349 2350 2351 2352 |
*/ if (likely(!plist_node_empty(&q->list))) { /* * If the timer has already expired, current will already be * flagged for rescheduling. Only call schedule if there * is no timeout, or if it has yet to expire. */ if (!timeout || timeout->task) |
88c8004fd futex: Use freeza... |
2353 |
freezable_schedule(); |
ca5f9524d futex: separate f... |
2354 2355 2356 |
} __set_current_state(TASK_RUNNING); } |
f801073f8 futex: split out ... |
2357 2358 2359 2360 |
/** * futex_wait_setup() - Prepare to wait on a futex * @uaddr: the futex userspace address * @val: the expected value |
b41277dc7 futex: Replace fs... |
2361 |
* @flags: futex flags (FLAGS_SHARED, etc.) |
f801073f8 futex: split out ... |
2362 2363 2364 2365 2366 2367 2368 2369 |
* @q: the associated futex_q * @hb: storage for hash_bucket pointer to be returned to caller * * Setup the futex_q and locate the hash_bucket. Get the futex value and * compare it with the expected value. Handle atomic faults internally. * Return with the hb lock held and a q.key reference on success, and unlocked * with no q.key reference on failure. * |
6c23cbbd5 futex: fix kernel... |
2370 |
* Return: |
7b4ff1adb mutex, futex: adj... |
2371 2372 |
* - 0 - uaddr contains val and hb has been locked; * - <1 - -EFAULT or -EWOULDBLOCK (uaddr does not contain val) and hb is unlocked |
f801073f8 futex: split out ... |
2373 |
*/ |
b41277dc7 futex: Replace fs... |
2374 |
static int futex_wait_setup(u32 __user *uaddr, u32 val, unsigned int flags, |
f801073f8 futex: split out ... |
2375 |
struct futex_q *q, struct futex_hash_bucket **hb) |
1da177e4c Linux-2.6.12-rc2 |
2376 |
{ |
e2970f2fb [PATCH] pi-futex:... |
2377 2378 |
u32 uval; int ret; |
1da177e4c Linux-2.6.12-rc2 |
2379 |
|
1da177e4c Linux-2.6.12-rc2 |
2380 |
/* |
b2d0994b1 futex: update fut... |
2381 |
* Access the page AFTER the hash-bucket is locked. |
1da177e4c Linux-2.6.12-rc2 |
2382 2383 2384 2385 2386 2387 2388 |
* Order is important: * * Userspace waiter: val = var; if (cond(val)) futex_wait(&var, val); * Userspace waker: if (cond(var)) { var = new; futex_wake(&var); } * * The basic logical guarantee of a futex is that it blocks ONLY * if cond(var) is known to be true at the time of blocking, for |
8fe8f545c futex: Update fut... |
2389 2390 |
* any cond. If we locked the hash-bucket after testing *uaddr, that * would open a race condition where we could block indefinitely with |
1da177e4c Linux-2.6.12-rc2 |
2391 2392 |
* cond(var) false, which would violate the guarantee. * |
8fe8f545c futex: Update fut... |
2393 2394 2395 2396 |
* On the other hand, we insert q and release the hash-bucket only * after testing *uaddr. This guarantees that futex_wait() will NOT * absorb a wakeup if *uaddr does not match the desired values * while the syscall executes. |
1da177e4c Linux-2.6.12-rc2 |
2397 |
*/ |
f801073f8 futex: split out ... |
2398 |
retry: |
9ea71503a futex: Fix regres... |
2399 |
ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &q->key, VERIFY_READ); |
f801073f8 futex: split out ... |
2400 |
if (unlikely(ret != 0)) |
a5a2a0c7f futex: fix futex_... |
2401 |
return ret; |
f801073f8 futex: split out ... |
2402 2403 2404 |
retry_private: *hb = queue_lock(q); |
e2970f2fb [PATCH] pi-futex:... |
2405 |
ret = get_futex_value_locked(&uval, uaddr); |
1da177e4c Linux-2.6.12-rc2 |
2406 |
|
f801073f8 futex: split out ... |
2407 |
if (ret) { |
0d00c7b20 futexes: Clean up... |
2408 |
queue_unlock(*hb); |
1da177e4c Linux-2.6.12-rc2 |
2409 |
|
e2970f2fb [PATCH] pi-futex:... |
2410 |
ret = get_user(uval, uaddr); |
e4dc5b7a3 futex: clean up f... |
2411 |
if (ret) |
f801073f8 futex: split out ... |
2412 |
goto out; |
1da177e4c Linux-2.6.12-rc2 |
2413 |
|
b41277dc7 futex: Replace fs... |
2414 |
if (!(flags & FLAGS_SHARED)) |
e4dc5b7a3 futex: clean up f... |
2415 |
goto retry_private; |
ae791a2d2 futex: Cleanup st... |
2416 |
put_futex_key(&q->key); |
e4dc5b7a3 futex: clean up f... |
2417 |
goto retry; |
1da177e4c Linux-2.6.12-rc2 |
2418 |
} |
ca5f9524d futex: separate f... |
2419 |
|
f801073f8 futex: split out ... |
2420 |
if (uval != val) { |
0d00c7b20 futexes: Clean up... |
2421 |
queue_unlock(*hb); |
f801073f8 futex: split out ... |
2422 |
ret = -EWOULDBLOCK; |
2fff78c78 futex: fix refere... |
2423 |
} |
1da177e4c Linux-2.6.12-rc2 |
2424 |
|
f801073f8 futex: split out ... |
2425 2426 |
out: if (ret) |
ae791a2d2 futex: Cleanup st... |
2427 |
put_futex_key(&q->key); |
f801073f8 futex: split out ... |
2428 2429 |
return ret; } |
b41277dc7 futex: Replace fs... |
2430 2431 |
static int futex_wait(u32 __user *uaddr, unsigned int flags, u32 val, ktime_t *abs_time, u32 bitset) |
f801073f8 futex: split out ... |
2432 2433 |
{ struct hrtimer_sleeper timeout, *to = NULL; |
f801073f8 futex: split out ... |
2434 2435 |
struct restart_block *restart; struct futex_hash_bucket *hb; |
5bdb05f91 futex: Add futex_... |
2436 |
struct futex_q q = futex_q_init; |
f801073f8 futex: split out ... |
2437 2438 2439 2440 |
int ret; if (!bitset) return -EINVAL; |
f801073f8 futex: split out ... |
2441 2442 2443 2444 |
q.bitset = bitset; if (abs_time) { to = &timeout; |
b41277dc7 futex: Replace fs... |
2445 2446 2447 |
hrtimer_init_on_stack(&to->timer, (flags & FLAGS_CLOCKRT) ? CLOCK_REALTIME : CLOCK_MONOTONIC, HRTIMER_MODE_ABS); |
f801073f8 futex: split out ... |
2448 2449 2450 2451 |
hrtimer_init_sleeper(to, current); hrtimer_set_expires_range_ns(&to->timer, *abs_time, current->timer_slack_ns); } |
d58e6576b futex: Handle spu... |
2452 |
retry: |
7ada876a8 futex: Fix errors... |
2453 2454 2455 2456 |
/* * Prepare to wait on uaddr. On success, holds hb lock and increments * q.key refs. */ |
b41277dc7 futex: Replace fs... |
2457 |
ret = futex_wait_setup(uaddr, val, flags, &q, &hb); |
f801073f8 futex: split out ... |
2458 2459 |
if (ret) goto out; |
ca5f9524d futex: separate f... |
2460 |
/* queue_me and wait for wakeup, timeout, or a signal. */ |
f1a11e057 futex: remove the... |
2461 |
futex_wait_queue_me(hb, &q, to); |
1da177e4c Linux-2.6.12-rc2 |
2462 2463 |
/* If we were woken (and unqueued), we succeeded, whatever. */ |
2fff78c78 futex: fix refere... |
2464 |
ret = 0; |
7ada876a8 futex: Fix errors... |
2465 |
/* unqueue_me() drops q.key ref */ |
1da177e4c Linux-2.6.12-rc2 |
2466 |
if (!unqueue_me(&q)) |
7ada876a8 futex: Fix errors... |
2467 |
goto out; |
2fff78c78 futex: fix refere... |
2468 |
ret = -ETIMEDOUT; |
ca5f9524d futex: separate f... |
2469 |
if (to && !to->task) |
7ada876a8 futex: Fix errors... |
2470 |
goto out; |
72c1bbf30 futex: restartabl... |
2471 |
|
e2970f2fb [PATCH] pi-futex:... |
2472 |
/* |
d58e6576b futex: Handle spu... |
2473 2474 |
* We expect signal_pending(current), but we might be the * victim of a spurious wakeup as well. |
e2970f2fb [PATCH] pi-futex:... |
2475 |
*/ |
7ada876a8 futex: Fix errors... |
2476 |
if (!signal_pending(current)) |
d58e6576b futex: Handle spu... |
2477 |
goto retry; |
d58e6576b futex: Handle spu... |
2478 |
|
2fff78c78 futex: fix refere... |
2479 |
ret = -ERESTARTSYS; |
c19384b5b Make futex_wait()... |
2480 |
if (!abs_time) |
7ada876a8 futex: Fix errors... |
2481 |
goto out; |
1da177e4c Linux-2.6.12-rc2 |
2482 |
|
f56141e3e all arches, signa... |
2483 |
restart = ¤t->restart_block; |
2fff78c78 futex: fix refere... |
2484 |
restart->fn = futex_wait_restart; |
a3c74c525 futex: Mark resta... |
2485 |
restart->futex.uaddr = uaddr; |
2fff78c78 futex: fix refere... |
2486 |
restart->futex.val = val; |
2456e8553 ktime: Get rid of... |
2487 |
restart->futex.time = *abs_time; |
2fff78c78 futex: fix refere... |
2488 |
restart->futex.bitset = bitset; |
0cd9c6494 futex: Set FLAGS_... |
2489 |
restart->futex.flags = flags | FLAGS_HAS_TIMEOUT; |
42d35d48c futex: make futex... |
2490 |
|
2fff78c78 futex: fix refere... |
2491 |
ret = -ERESTART_RESTARTBLOCK; |
42d35d48c futex: make futex... |
2492 |
out: |
ca5f9524d futex: separate f... |
2493 2494 2495 2496 |
if (to) { hrtimer_cancel(&to->timer); destroy_hrtimer_on_stack(&to->timer); } |
c87e2837b [PATCH] pi-futex:... |
2497 2498 |
return ret; } |
72c1bbf30 futex: restartabl... |
2499 2500 2501 |
static long futex_wait_restart(struct restart_block *restart) { |
a3c74c525 futex: Mark resta... |
2502 |
u32 __user *uaddr = restart->futex.uaddr; |
a72188d8a futex: add FUTEX_... |
2503 |
ktime_t t, *tp = NULL; |
72c1bbf30 futex: restartabl... |
2504 |
|
a72188d8a futex: add FUTEX_... |
2505 |
if (restart->futex.flags & FLAGS_HAS_TIMEOUT) { |
2456e8553 ktime: Get rid of... |
2506 |
t = restart->futex.time; |
a72188d8a futex: add FUTEX_... |
2507 2508 |
tp = &t; } |
72c1bbf30 futex: restartabl... |
2509 |
restart->fn = do_no_restart_syscall; |
b41277dc7 futex: Replace fs... |
2510 2511 2512 |
return (long)futex_wait(uaddr, restart->futex.flags, restart->futex.val, tp, restart->futex.bitset); |
72c1bbf30 futex: restartabl... |
2513 |
} |
c87e2837b [PATCH] pi-futex:... |
2514 2515 2516 |
/* * Userspace tried a 0 -> TID atomic transition of the futex value * and failed. The kernel side here does the whole locking operation: |
767f509ca futex: Enhance co... |
2517 2518 2519 2520 2521 |
* if there are waiters then it will block as a consequence of relying * on rt-mutexes, it does PI, etc. (Due to races the kernel might see * a 0 value of the futex too.). * * Also serves as futex trylock_pi()'ing, and due semantics. |
c87e2837b [PATCH] pi-futex:... |
2522 |
*/ |
996636dda futex: Fix argume... |
2523 |
static int futex_lock_pi(u32 __user *uaddr, unsigned int flags, |
b41277dc7 futex: Replace fs... |
2524 |
ktime_t *time, int trylock) |
c87e2837b [PATCH] pi-futex:... |
2525 |
{ |
c5780e976 [PATCH] Use the c... |
2526 |
struct hrtimer_sleeper timeout, *to = NULL; |
16ffa12d7 futex: Pull rt_mu... |
2527 |
struct futex_pi_state *pi_state = NULL; |
cfafcd117 futex: Rework fut... |
2528 |
struct rt_mutex_waiter rt_waiter; |
c87e2837b [PATCH] pi-futex:... |
2529 |
struct futex_hash_bucket *hb; |
5bdb05f91 futex: Add futex_... |
2530 |
struct futex_q q = futex_q_init; |
dd9739980 futex: split out ... |
2531 |
int res, ret; |
c87e2837b [PATCH] pi-futex:... |
2532 |
|
bc2eecd7e futex: Allow for ... |
2533 2534 |
if (!IS_ENABLED(CONFIG_FUTEX_PI)) return -ENOSYS; |
c87e2837b [PATCH] pi-futex:... |
2535 2536 |
if (refill_pi_state_cache()) return -ENOMEM; |
c19384b5b Make futex_wait()... |
2537 |
if (time) { |
c5780e976 [PATCH] Use the c... |
2538 |
to = &timeout; |
237fc6e7a add hrtimer speci... |
2539 2540 |
hrtimer_init_on_stack(&to->timer, CLOCK_REALTIME, HRTIMER_MODE_ABS); |
c5780e976 [PATCH] Use the c... |
2541 |
hrtimer_init_sleeper(to, current); |
cc584b213 hrtimer: convert ... |
2542 |
hrtimer_set_expires(&to->timer, *time); |
c5780e976 [PATCH] Use the c... |
2543 |
} |
42d35d48c futex: make futex... |
2544 |
retry: |
9ea71503a futex: Fix regres... |
2545 |
ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &q.key, VERIFY_WRITE); |
c87e2837b [PATCH] pi-futex:... |
2546 |
if (unlikely(ret != 0)) |
42d35d48c futex: make futex... |
2547 |
goto out; |
c87e2837b [PATCH] pi-futex:... |
2548 |
|
e4dc5b7a3 futex: clean up f... |
2549 |
retry_private: |
82af7aca5 Removal of FUTEX_FD |
2550 |
hb = queue_lock(&q); |
c87e2837b [PATCH] pi-futex:... |
2551 |
|
bab5bc9e8 futex: fixup unlo... |
2552 |
ret = futex_lock_pi_atomic(uaddr, hb, &q.key, &q.pi_state, current, 0); |
c87e2837b [PATCH] pi-futex:... |
2553 |
if (unlikely(ret)) { |
767f509ca futex: Enhance co... |
2554 2555 2556 2557 |
/* * Atomic work succeeded and we got the lock, * or failed. Either way, we do _not_ block. */ |
778e9a9c3 pi-futex: fix exi... |
2558 |
switch (ret) { |
1a52084d0 futex: split out ... |
2559 2560 2561 2562 2563 2564 |
case 1: /* We got the lock. */ ret = 0; goto out_unlock_put_key; case -EFAULT: goto uaddr_faulted; |
778e9a9c3 pi-futex: fix exi... |
2565 2566 |
case -EAGAIN: /* |
af54d6a1c futex: Simplify f... |
2567 2568 2569 2570 |
* Two reasons for this: * - Task is exiting and we just wait for the * exit to complete. * - The user space value changed. |
778e9a9c3 pi-futex: fix exi... |
2571 |
*/ |
0d00c7b20 futexes: Clean up... |
2572 |
queue_unlock(hb); |
ae791a2d2 futex: Cleanup st... |
2573 |
put_futex_key(&q.key); |
778e9a9c3 pi-futex: fix exi... |
2574 2575 |
cond_resched(); goto retry; |
778e9a9c3 pi-futex: fix exi... |
2576 |
default: |
42d35d48c futex: make futex... |
2577 |
goto out_unlock_put_key; |
c87e2837b [PATCH] pi-futex:... |
2578 |
} |
c87e2837b [PATCH] pi-futex:... |
2579 |
} |
cfafcd117 futex: Rework fut... |
2580 |
WARN_ON(!q.pi_state); |
c87e2837b [PATCH] pi-futex:... |
2581 2582 2583 |
/* * Only actually queue now that the atomic ops are done: */ |
cfafcd117 futex: Rework fut... |
2584 |
__queue_me(&q, hb); |
c87e2837b [PATCH] pi-futex:... |
2585 |
|
cfafcd117 futex: Rework fut... |
2586 |
if (trylock) { |
5293c2efd futex,rt_mutex: P... |
2587 |
ret = rt_mutex_futex_trylock(&q.pi_state->pi_mutex); |
c87e2837b [PATCH] pi-futex:... |
2588 2589 |
/* Fixup the trylock return value: */ ret = ret ? 0 : -EWOULDBLOCK; |
cfafcd117 futex: Rework fut... |
2590 |
goto no_block; |
c87e2837b [PATCH] pi-futex:... |
2591 |
} |
56222b212 futex: Drop hb->l... |
2592 |
rt_mutex_init_waiter(&rt_waiter); |
cfafcd117 futex: Rework fut... |
2593 |
/* |
56222b212 futex: Drop hb->l... |
2594 2595 2596 2597 2598 2599 2600 2601 2602 2603 |
* On PREEMPT_RT_FULL, when hb->lock becomes an rt_mutex, we must not * hold it while doing rt_mutex_start_proxy(), because then it will * include hb->lock in the blocking chain, even through we'll not in * fact hold it while blocking. This will lead it to report -EDEADLK * and BUG when futex_unlock_pi() interleaves with this. * * Therefore acquire wait_lock while holding hb->lock, but drop the * latter before calling rt_mutex_start_proxy_lock(). This still fully * serializes against futex_unlock_pi() as that does the exact same * lock handoff sequence. |
cfafcd117 futex: Rework fut... |
2604 |
*/ |
56222b212 futex: Drop hb->l... |
2605 2606 2607 2608 |
raw_spin_lock_irq(&q.pi_state->pi_mutex.wait_lock); spin_unlock(q.lock_ptr); ret = __rt_mutex_start_proxy_lock(&q.pi_state->pi_mutex, &rt_waiter, current); raw_spin_unlock_irq(&q.pi_state->pi_mutex.wait_lock); |
cfafcd117 futex: Rework fut... |
2609 2610 2611 |
if (ret) { if (ret == 1) ret = 0; |
56222b212 futex: Drop hb->l... |
2612 |
spin_lock(q.lock_ptr); |
cfafcd117 futex: Rework fut... |
2613 2614 |
goto no_block; } |
cfafcd117 futex: Rework fut... |
2615 2616 2617 2618 2619 |
if (unlikely(to)) hrtimer_start_expires(&to->timer, HRTIMER_MODE_ABS); ret = rt_mutex_wait_proxy_lock(&q.pi_state->pi_mutex, to, &rt_waiter); |
a99e4e413 [PATCH] pi-futex:... |
2620 |
spin_lock(q.lock_ptr); |
dd9739980 futex: split out ... |
2621 |
/* |
cfafcd117 futex: Rework fut... |
2622 2623 2624 2625 |
* If we failed to acquire the lock (signal/timeout), we must * first acquire the hb->lock before removing the lock from the * rt_mutex waitqueue, such that we can keep the hb and rt_mutex * wait lists consistent. |
56222b212 futex: Drop hb->l... |
2626 2627 2628 |
* * In particular; it is important that futex_unlock_pi() can not * observe this inconsistency. |
cfafcd117 futex: Rework fut... |
2629 2630 2631 2632 2633 2634 |
*/ if (ret && !rt_mutex_cleanup_proxy_lock(&q.pi_state->pi_mutex, &rt_waiter)) ret = 0; no_block: /* |
dd9739980 futex: split out ... |
2635 2636 2637 |
* Fixup the pi_state owner and possibly acquire the lock if we * haven't already. */ |
ae791a2d2 futex: Cleanup st... |
2638 |
res = fixup_owner(uaddr, &q, !ret); |
dd9739980 futex: split out ... |
2639 2640 2641 2642 2643 2644 |
/* * If fixup_owner() returned an error, proprogate that. If it acquired * the lock, clear our -ETIMEDOUT or -EINTR. */ if (res) ret = (res < 0) ? res : 0; |
c87e2837b [PATCH] pi-futex:... |
2645 |
|
e8f6386c0 futex: unlock bef... |
2646 |
/* |
dd9739980 futex: split out ... |
2647 2648 |
* If fixup_owner() faulted and was unable to handle the fault, unlock * it and return the fault to userspace. |
e8f6386c0 futex: unlock bef... |
2649 |
*/ |
16ffa12d7 futex: Pull rt_mu... |
2650 2651 2652 2653 |
if (ret && (rt_mutex_owner(&q.pi_state->pi_mutex) == current)) { pi_state = q.pi_state; get_pi_state(pi_state); } |
e8f6386c0 futex: unlock bef... |
2654 |
|
778e9a9c3 pi-futex: fix exi... |
2655 2656 |
/* Unqueue and drop the lock */ unqueue_me_pi(&q); |
c87e2837b [PATCH] pi-futex:... |
2657 |
|
16ffa12d7 futex: Pull rt_mu... |
2658 2659 2660 2661 |
if (pi_state) { rt_mutex_futex_unlock(&pi_state->pi_mutex); put_pi_state(pi_state); } |
5ecb01cfd futex_lock_pi() k... |
2662 |
goto out_put_key; |
c87e2837b [PATCH] pi-futex:... |
2663 |
|
42d35d48c futex: make futex... |
2664 |
out_unlock_put_key: |
0d00c7b20 futexes: Clean up... |
2665 |
queue_unlock(hb); |
c87e2837b [PATCH] pi-futex:... |
2666 |
|
42d35d48c futex: make futex... |
2667 |
out_put_key: |
ae791a2d2 futex: Cleanup st... |
2668 |
put_futex_key(&q.key); |
42d35d48c futex: make futex... |
2669 |
out: |
97181f9bd futex: Avoid free... |
2670 2671 |
if (to) { hrtimer_cancel(&to->timer); |
237fc6e7a add hrtimer speci... |
2672 |
destroy_hrtimer_on_stack(&to->timer); |
97181f9bd futex: Avoid free... |
2673 |
} |
dd9739980 futex: split out ... |
2674 |
return ret != -EINTR ? ret : -ERESTARTNOINTR; |
c87e2837b [PATCH] pi-futex:... |
2675 |
|
42d35d48c futex: make futex... |
2676 |
uaddr_faulted: |
0d00c7b20 futexes: Clean up... |
2677 |
queue_unlock(hb); |
778e9a9c3 pi-futex: fix exi... |
2678 |
|
d0725992c futex: Fix the wr... |
2679 |
ret = fault_in_user_writeable(uaddr); |
e4dc5b7a3 futex: clean up f... |
2680 2681 |
if (ret) goto out_put_key; |
c87e2837b [PATCH] pi-futex:... |
2682 |
|
b41277dc7 futex: Replace fs... |
2683 |
if (!(flags & FLAGS_SHARED)) |
e4dc5b7a3 futex: clean up f... |
2684 |
goto retry_private; |
ae791a2d2 futex: Cleanup st... |
2685 |
put_futex_key(&q.key); |
e4dc5b7a3 futex: clean up f... |
2686 |
goto retry; |
c87e2837b [PATCH] pi-futex:... |
2687 2688 2689 |
} /* |
c87e2837b [PATCH] pi-futex:... |
2690 2691 2692 2693 |
* Userspace attempted a TID -> 0 atomic transition, and failed. * This is the in-kernel slowpath: we look up the PI state (if any), * and do the rt-mutex unlock. */ |
b41277dc7 futex: Replace fs... |
2694 |
static int futex_unlock_pi(u32 __user *uaddr, unsigned int flags) |
c87e2837b [PATCH] pi-futex:... |
2695 |
{ |
ccf9e6a80 futex: Make unloc... |
2696 |
u32 uninitialized_var(curval), uval, vpid = task_pid_vnr(current); |
38d47c1b7 futex: rely on ge... |
2697 |
union futex_key key = FUTEX_KEY_INIT; |
ccf9e6a80 futex: Make unloc... |
2698 |
struct futex_hash_bucket *hb; |
499f5aca2 futex: Cleanup va... |
2699 |
struct futex_q *top_waiter; |
e4dc5b7a3 futex: clean up f... |
2700 |
int ret; |
c87e2837b [PATCH] pi-futex:... |
2701 |
|
bc2eecd7e futex: Allow for ... |
2702 2703 |
if (!IS_ENABLED(CONFIG_FUTEX_PI)) return -ENOSYS; |
c87e2837b [PATCH] pi-futex:... |
2704 2705 2706 2707 2708 2709 |
retry: if (get_user(uval, uaddr)) return -EFAULT; /* * We release only a lock we actually own: */ |
c0c9ed150 futex: Avoid redu... |
2710 |
if ((uval & FUTEX_TID_MASK) != vpid) |
c87e2837b [PATCH] pi-futex:... |
2711 |
return -EPERM; |
c87e2837b [PATCH] pi-futex:... |
2712 |
|
9ea71503a futex: Fix regres... |
2713 |
ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &key, VERIFY_WRITE); |
ccf9e6a80 futex: Make unloc... |
2714 2715 |
if (ret) return ret; |
c87e2837b [PATCH] pi-futex:... |
2716 2717 2718 |
hb = hash_futex(&key); spin_lock(&hb->lock); |
c87e2837b [PATCH] pi-futex:... |
2719 |
/* |
ccf9e6a80 futex: Make unloc... |
2720 2721 2722 |
* Check waiters first. We do not trust user space values at * all and we at least want to know if user space fiddled * with the futex value instead of blindly unlocking. |
c87e2837b [PATCH] pi-futex:... |
2723 |
*/ |
499f5aca2 futex: Cleanup va... |
2724 2725 |
top_waiter = futex_top_waiter(hb, &key); if (top_waiter) { |
16ffa12d7 futex: Pull rt_mu... |
2726 2727 2728 2729 2730 2731 2732 2733 2734 2735 2736 2737 |
struct futex_pi_state *pi_state = top_waiter->pi_state; ret = -EINVAL; if (!pi_state) goto out_unlock; /* * If current does not own the pi_state then the futex is * inconsistent and user space fiddled with the futex value. */ if (pi_state->owner != current) goto out_unlock; |
bebe5b514 futex: Futex_unlo... |
2738 |
get_pi_state(pi_state); |
802ab58da futex: Lower the ... |
2739 |
/* |
bebe5b514 futex: Futex_unlo... |
2740 2741 2742 2743 |
* By taking wait_lock while still holding hb->lock, we ensure * there is no point where we hold neither; and therefore * wake_futex_pi() must observe a state consistent with what we * observed. |
16ffa12d7 futex: Pull rt_mu... |
2744 |
*/ |
bebe5b514 futex: Futex_unlo... |
2745 |
raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock); |
16ffa12d7 futex: Pull rt_mu... |
2746 2747 2748 2749 2750 2751 2752 2753 |
spin_unlock(&hb->lock); ret = wake_futex_pi(uaddr, uval, pi_state); put_pi_state(pi_state); /* * Success, we're done! No tricky corner cases. |
802ab58da futex: Lower the ... |
2754 2755 2756 |
*/ if (!ret) goto out_putkey; |
c87e2837b [PATCH] pi-futex:... |
2757 |
/* |
ccf9e6a80 futex: Make unloc... |
2758 2759 |
* The atomic access to the futex value generated a * pagefault, so retry the user-access and the wakeup: |
c87e2837b [PATCH] pi-futex:... |
2760 2761 2762 |
*/ if (ret == -EFAULT) goto pi_faulted; |
802ab58da futex: Lower the ... |
2763 |
/* |
89e9e66ba futex: Handle unl... |
2764 2765 2766 2767 |
* A unconditional UNLOCK_PI op raced against a waiter * setting the FUTEX_WAITERS bit. Try again. */ if (ret == -EAGAIN) { |
89e9e66ba futex: Handle unl... |
2768 2769 2770 2771 |
put_futex_key(&key); goto retry; } /* |
802ab58da futex: Lower the ... |
2772 2773 2774 |
* wake_futex_pi has detected invalid state. Tell user * space. */ |
16ffa12d7 futex: Pull rt_mu... |
2775 |
goto out_putkey; |
c87e2837b [PATCH] pi-futex:... |
2776 |
} |
ccf9e6a80 futex: Make unloc... |
2777 |
|
c87e2837b [PATCH] pi-futex:... |
2778 |
/* |
ccf9e6a80 futex: Make unloc... |
2779 2780 2781 2782 2783 |
* We have no kernel internal state, i.e. no waiters in the * kernel. Waiters which are about to queue themselves are stuck * on hb->lock. So we can safely ignore them. We do neither * preserve the WAITERS bit not the OWNER_DIED one. We are the * owner. |
c87e2837b [PATCH] pi-futex:... |
2784 |
*/ |
16ffa12d7 futex: Pull rt_mu... |
2785 2786 |
if (cmpxchg_futex_value_locked(&curval, uaddr, uval, 0)) { spin_unlock(&hb->lock); |
13fbca4c6 futex: Always cle... |
2787 |
goto pi_faulted; |
16ffa12d7 futex: Pull rt_mu... |
2788 |
} |
c87e2837b [PATCH] pi-futex:... |
2789 |
|
ccf9e6a80 futex: Make unloc... |
2790 2791 2792 2793 |
/* * If uval has changed, let user space handle it. */ ret = (curval == uval) ? 0 : -EAGAIN; |
c87e2837b [PATCH] pi-futex:... |
2794 2795 |
out_unlock: spin_unlock(&hb->lock); |
802ab58da futex: Lower the ... |
2796 |
out_putkey: |
ae791a2d2 futex: Cleanup st... |
2797 |
put_futex_key(&key); |
c87e2837b [PATCH] pi-futex:... |
2798 2799 2800 |
return ret; pi_faulted: |
ae791a2d2 futex: Cleanup st... |
2801 |
put_futex_key(&key); |
c87e2837b [PATCH] pi-futex:... |
2802 |
|
d0725992c futex: Fix the wr... |
2803 |
ret = fault_in_user_writeable(uaddr); |
b56863630 futex: clean up f... |
2804 |
if (!ret) |
c87e2837b [PATCH] pi-futex:... |
2805 |
goto retry; |
1da177e4c Linux-2.6.12-rc2 |
2806 2807 |
return ret; } |
52400ba94 futex: add requeu... |
2808 2809 2810 2811 2812 2813 2814 2815 2816 2817 2818 2819 |
/** * handle_early_requeue_pi_wakeup() - Detect early wakeup on the initial futex * @hb: the hash_bucket futex_q was original enqueued on * @q: the futex_q woken while waiting to be requeued * @key2: the futex_key of the requeue target futex * @timeout: the timeout associated with the wait (NULL if none) * * Detect if the task was woken on the initial futex as opposed to the requeue * target futex. If so, determine if it was a timeout or a signal that caused * the wakeup and return the appropriate error code to the caller. Must be * called with the hb lock held. * |
6c23cbbd5 futex: fix kernel... |
2820 |
* Return: |
7b4ff1adb mutex, futex: adj... |
2821 2822 |
* - 0 = no early wakeup detected; * - <0 = -ETIMEDOUT or -ERESTARTNOINTR |
52400ba94 futex: add requeu... |
2823 2824 2825 2826 2827 2828 2829 2830 2831 2832 2833 2834 2835 2836 2837 2838 2839 2840 2841 2842 2843 |
*/ static inline int handle_early_requeue_pi_wakeup(struct futex_hash_bucket *hb, struct futex_q *q, union futex_key *key2, struct hrtimer_sleeper *timeout) { int ret = 0; /* * With the hb lock held, we avoid races while we process the wakeup. * We only need to hold hb (and not hb2) to ensure atomicity as the * wakeup code can't change q.key from uaddr to uaddr2 if we hold hb. * It can't be requeued from uaddr2 to something else since we don't * support a PI aware source futex for requeue. */ if (!match_futex(&q->key, key2)) { WARN_ON(q->lock_ptr && (&hb->lock != q->lock_ptr)); /* * We were woken prior to requeue by a timeout or a signal. * Unqueue the futex_q and determine which it was. */ |
2e12978a9 futex,plist: Pass... |
2844 |
plist_del(&q->list, &hb->chain); |
11d4616bd futex: revert bac... |
2845 |
hb_waiters_dec(hb); |
52400ba94 futex: add requeu... |
2846 |
|
d58e6576b futex: Handle spu... |
2847 |
/* Handle spurious wakeups gracefully */ |
11df6dddc futex: Fix spurio... |
2848 |
ret = -EWOULDBLOCK; |
52400ba94 futex: add requeu... |
2849 2850 |
if (timeout && !timeout->task) ret = -ETIMEDOUT; |
d58e6576b futex: Handle spu... |
2851 |
else if (signal_pending(current)) |
1c840c149 futex: fix restar... |
2852 |
ret = -ERESTARTNOINTR; |
52400ba94 futex: add requeu... |
2853 2854 2855 2856 2857 2858 |
} return ret; } /** * futex_wait_requeue_pi() - Wait on uaddr and take uaddr2 |
56ec1607b futex: Correct fu... |
2859 |
* @uaddr: the futex we initially wait on (non-pi) |
b41277dc7 futex: Replace fs... |
2860 |
* @flags: futex flags (FLAGS_SHARED, FLAGS_CLOCKRT, etc.), they must be |
ab51fbab3 futex: Fault/erro... |
2861 |
* the same type, no requeueing from private to shared, etc. |
52400ba94 futex: add requeu... |
2862 2863 |
* @val: the expected value of uaddr * @abs_time: absolute timeout |
56ec1607b futex: Correct fu... |
2864 |
* @bitset: 32 bit wakeup bitset set by userspace, defaults to all |
52400ba94 futex: add requeu... |
2865 2866 2867 |
* @uaddr2: the pi futex we will take prior to returning to user-space * * The caller will wait on uaddr and will be requeued by futex_requeue() to |
6f7b0a2a5 futex: Forbid uad... |
2868 2869 2870 2871 2872 |
* uaddr2 which must be PI aware and unique from uaddr. Normal wakeup will wake * on uaddr2 and complete the acquisition of the rt_mutex prior to returning to * userspace. This ensures the rt_mutex maintains an owner when it has waiters; * without one, the pi logic would not know which task to boost/deboost, if * there was a need to. |
52400ba94 futex: add requeu... |
2873 2874 |
* * We call schedule in futex_wait_queue_me() when we enqueue and return there |
6c23cbbd5 futex: fix kernel... |
2875 |
* via the following-- |
52400ba94 futex: add requeu... |
2876 |
* 1) wakeup on uaddr2 after an atomic lock acquisition by futex_requeue() |
cc6db4e60 futex: Correct fu... |
2877 2878 2879 |
* 2) wakeup on uaddr2 after a requeue * 3) signal * 4) timeout |
52400ba94 futex: add requeu... |
2880 |
* |
cc6db4e60 futex: Correct fu... |
2881 |
* If 3, cleanup and return -ERESTARTNOINTR. |
52400ba94 futex: add requeu... |
2882 2883 2884 2885 2886 2887 2888 |
* * If 2, we may then block on trying to take the rt_mutex and return via: * 5) successful lock * 6) signal * 7) timeout * 8) other lock acquisition failure * |
cc6db4e60 futex: Correct fu... |
2889 |
* If 6, return -EWOULDBLOCK (restarting the syscall would do the same). |
52400ba94 futex: add requeu... |
2890 2891 2892 |
* * If 4 or 7, we cleanup and return with -ETIMEDOUT. * |
6c23cbbd5 futex: fix kernel... |
2893 |
* Return: |
7b4ff1adb mutex, futex: adj... |
2894 2895 |
* - 0 - On success; * - <0 - On error |
52400ba94 futex: add requeu... |
2896 |
*/ |
b41277dc7 futex: Replace fs... |
2897 |
static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags, |
52400ba94 futex: add requeu... |
2898 |
u32 val, ktime_t *abs_time, u32 bitset, |
b41277dc7 futex: Replace fs... |
2899 |
u32 __user *uaddr2) |
52400ba94 futex: add requeu... |
2900 2901 |
{ struct hrtimer_sleeper timeout, *to = NULL; |
16ffa12d7 futex: Pull rt_mu... |
2902 |
struct futex_pi_state *pi_state = NULL; |
52400ba94 futex: add requeu... |
2903 |
struct rt_mutex_waiter rt_waiter; |
52400ba94 futex: add requeu... |
2904 |
struct futex_hash_bucket *hb; |
5bdb05f91 futex: Add futex_... |
2905 2906 |
union futex_key key2 = FUTEX_KEY_INIT; struct futex_q q = futex_q_init; |
52400ba94 futex: add requeu... |
2907 |
int res, ret; |
52400ba94 futex: add requeu... |
2908 |
|
bc2eecd7e futex: Allow for ... |
2909 2910 |
if (!IS_ENABLED(CONFIG_FUTEX_PI)) return -ENOSYS; |
6f7b0a2a5 futex: Forbid uad... |
2911 2912 |
if (uaddr == uaddr2) return -EINVAL; |
52400ba94 futex: add requeu... |
2913 2914 2915 2916 2917 |
if (!bitset) return -EINVAL; if (abs_time) { to = &timeout; |
b41277dc7 futex: Replace fs... |
2918 2919 2920 |
hrtimer_init_on_stack(&to->timer, (flags & FLAGS_CLOCKRT) ? CLOCK_REALTIME : CLOCK_MONOTONIC, HRTIMER_MODE_ABS); |
52400ba94 futex: add requeu... |
2921 2922 2923 2924 2925 2926 2927 2928 2929 |
hrtimer_init_sleeper(to, current); hrtimer_set_expires_range_ns(&to->timer, *abs_time, current->timer_slack_ns); } /* * The waiter is allocated on our stack, manipulated by the requeue * code while we sleep on uaddr. */ |
50809358d futex,rt_mutex: I... |
2930 |
rt_mutex_init_waiter(&rt_waiter); |
52400ba94 futex: add requeu... |
2931 |
|
9ea71503a futex: Fix regres... |
2932 |
ret = get_futex_key(uaddr2, flags & FLAGS_SHARED, &key2, VERIFY_WRITE); |
52400ba94 futex: add requeu... |
2933 2934 |
if (unlikely(ret != 0)) goto out; |
84bc4af59 futex: Detect mis... |
2935 2936 2937 |
q.bitset = bitset; q.rt_waiter = &rt_waiter; q.requeue_pi_key = &key2; |
7ada876a8 futex: Fix errors... |
2938 2939 2940 2941 |
/* * Prepare to wait on uaddr. On success, increments q.key (key1) ref * count. */ |
b41277dc7 futex: Replace fs... |
2942 |
ret = futex_wait_setup(uaddr, val, flags, &q, &hb); |
c8b15a706 futex: cleanup er... |
2943 2944 |
if (ret) goto out_key2; |
52400ba94 futex: add requeu... |
2945 |
|
e9c243a5a futex-prevent-req... |
2946 2947 2948 2949 2950 |
/* * The check above which compares uaddrs is not sufficient for * shared futexes. We need to compare the keys: */ if (match_futex(&q.key, &key2)) { |
13c42c2f4 futex: Unlock hb-... |
2951 |
queue_unlock(hb); |
e9c243a5a futex-prevent-req... |
2952 2953 2954 |
ret = -EINVAL; goto out_put_keys; } |
52400ba94 futex: add requeu... |
2955 |
/* Queue the futex_q, drop the hb lock, wait for wakeup. */ |
f1a11e057 futex: remove the... |
2956 |
futex_wait_queue_me(hb, &q, to); |
52400ba94 futex: add requeu... |
2957 2958 2959 2960 2961 2962 2963 2964 2965 2966 2967 |
spin_lock(&hb->lock); ret = handle_early_requeue_pi_wakeup(hb, &q, &key2, to); spin_unlock(&hb->lock); if (ret) goto out_put_keys; /* * In order for us to be here, we know our q.key == key2, and since * we took the hb->lock above, we also know that futex_requeue() has * completed and we no longer have to concern ourselves with a wakeup |
7ada876a8 futex: Fix errors... |
2968 2969 2970 |
* race with the atomic proxy lock acquisition by the requeue code. The * futex_requeue dropped our key1 reference and incremented our key2 * reference count. |
52400ba94 futex: add requeu... |
2971 2972 2973 2974 2975 2976 2977 2978 2979 2980 |
*/ /* Check if the requeue code acquired the second futex for us. */ if (!q.rt_waiter) { /* * Got the lock. We might not be the anticipated owner if we * did a lock-steal - fix up the PI-state in that case. */ if (q.pi_state && (q.pi_state->owner != current)) { spin_lock(q.lock_ptr); |
ae791a2d2 futex: Cleanup st... |
2981 |
ret = fixup_pi_state_owner(uaddr2, &q, current); |
16ffa12d7 futex: Pull rt_mu... |
2982 2983 2984 2985 |
if (ret && rt_mutex_owner(&q.pi_state->pi_mutex) == current) { pi_state = q.pi_state; get_pi_state(pi_state); } |
fb75a4282 futex: Drop refco... |
2986 2987 2988 2989 |
/* * Drop the reference to the pi state which * the requeue_pi() code acquired for us. */ |
29e9ee5d4 futex: Rename fre... |
2990 |
put_pi_state(q.pi_state); |
52400ba94 futex: add requeu... |
2991 2992 2993 |
spin_unlock(q.lock_ptr); } } else { |
c236c8e95 futex: Fix potent... |
2994 |
struct rt_mutex *pi_mutex; |
52400ba94 futex: add requeu... |
2995 2996 2997 2998 2999 |
/* * We have been woken up by futex_unlock_pi(), a timeout, or a * signal. futex_unlock_pi() will not destroy the lock_ptr nor * the pi_state. */ |
f27071cb7 futex: Fix bug in... |
3000 |
WARN_ON(!q.pi_state); |
52400ba94 futex: add requeu... |
3001 |
pi_mutex = &q.pi_state->pi_mutex; |
38d589f2f futex,rt_mutex: R... |
3002 |
ret = rt_mutex_wait_proxy_lock(pi_mutex, to, &rt_waiter); |
52400ba94 futex: add requeu... |
3003 3004 |
spin_lock(q.lock_ptr); |
38d589f2f futex,rt_mutex: R... |
3005 3006 3007 3008 |
if (ret && !rt_mutex_cleanup_proxy_lock(pi_mutex, &rt_waiter)) ret = 0; debug_rt_mutex_free_waiter(&rt_waiter); |
52400ba94 futex: add requeu... |
3009 3010 3011 3012 |
/* * Fixup the pi_state owner and possibly acquire the lock if we * haven't already. */ |
ae791a2d2 futex: Cleanup st... |
3013 |
res = fixup_owner(uaddr2, &q, !ret); |
52400ba94 futex: add requeu... |
3014 3015 |
/* * If fixup_owner() returned an error, proprogate that. If it |
56ec1607b futex: Correct fu... |
3016 |
* acquired the lock, clear -ETIMEDOUT or -EINTR. |
52400ba94 futex: add requeu... |
3017 3018 3019 |
*/ if (res) ret = (res < 0) ? res : 0; |
c236c8e95 futex: Fix potent... |
3020 3021 3022 3023 3024 |
/* * If fixup_pi_state_owner() faulted and was unable to handle * the fault, unlock the rt_mutex and return the fault to * userspace. */ |
16ffa12d7 futex: Pull rt_mu... |
3025 3026 3027 3028 |
if (ret && rt_mutex_owner(&q.pi_state->pi_mutex) == current) { pi_state = q.pi_state; get_pi_state(pi_state); } |
c236c8e95 futex: Fix potent... |
3029 |
|
52400ba94 futex: add requeu... |
3030 3031 3032 |
/* Unqueue and drop the lock. */ unqueue_me_pi(&q); } |
16ffa12d7 futex: Pull rt_mu... |
3033 3034 3035 3036 |
if (pi_state) { rt_mutex_futex_unlock(&pi_state->pi_mutex); put_pi_state(pi_state); } |
c236c8e95 futex: Fix potent... |
3037 |
if (ret == -EINTR) { |
52400ba94 futex: add requeu... |
3038 |
/* |
cc6db4e60 futex: Correct fu... |
3039 3040 3041 3042 3043 |
* We've already been requeued, but cannot restart by calling * futex_lock_pi() directly. We could restart this syscall, but * it would detect that the user space "val" changed and return * -EWOULDBLOCK. Save the overhead of the restart and return * -EWOULDBLOCK directly. |
52400ba94 futex: add requeu... |
3044 |
*/ |
2070887fd futex: fix restar... |
3045 |
ret = -EWOULDBLOCK; |
52400ba94 futex: add requeu... |
3046 3047 3048 |
} out_put_keys: |
ae791a2d2 futex: Cleanup st... |
3049 |
put_futex_key(&q.key); |
c8b15a706 futex: cleanup er... |
3050 |
out_key2: |
ae791a2d2 futex: Cleanup st... |
3051 |
put_futex_key(&key2); |
52400ba94 futex: add requeu... |
3052 3053 3054 3055 3056 3057 3058 3059 |
out: if (to) { hrtimer_cancel(&to->timer); destroy_hrtimer_on_stack(&to->timer); } return ret; } |
0771dfefc [PATCH] lightweig... |
3060 3061 3062 3063 3064 3065 3066 |
/* * Support for robust futexes: the kernel cleans up held futexes at * thread exit time. * * Implementation: user-space maintains a per-thread list of locks it * is holding. Upon do_exit(), the kernel carefully walks this list, * and marks all locks that are owned by this thread with the |
c87e2837b [PATCH] pi-futex:... |
3067 |
* FUTEX_OWNER_DIED bit, and wakes up a waiter (if any). The list is |
0771dfefc [PATCH] lightweig... |
3068 3069 3070 3071 3072 3073 3074 3075 |
* always manipulated with the lock held, so the list is private and * per-thread. Userspace also maintains a per-thread 'list_op_pending' * field, to allow the kernel to clean up if the thread dies after * acquiring the lock, but just before it could have added itself to * the list. There can only be one such pending lock. */ /** |
d96ee56ce futex: Make funct... |
3076 3077 3078 |
* sys_set_robust_list() - Set the robust-futex list head of a task * @head: pointer to the list-head * @len: length of the list-head, as userspace expects |
0771dfefc [PATCH] lightweig... |
3079 |
*/ |
836f92adf [CVE-2009-0029] S... |
3080 3081 |
SYSCALL_DEFINE2(set_robust_list, struct robust_list_head __user *, head, size_t, len) |
0771dfefc [PATCH] lightweig... |
3082 |
{ |
a0c1e9073 futex: runtime en... |
3083 3084 |
if (!futex_cmpxchg_enabled) return -ENOSYS; |
0771dfefc [PATCH] lightweig... |
3085 3086 3087 3088 3089 3090 3091 3092 3093 3094 3095 3096 |
/* * The kernel knows only one size for now: */ if (unlikely(len != sizeof(*head))) return -EINVAL; current->robust_list = head; return 0; } /** |
d96ee56ce futex: Make funct... |
3097 3098 3099 3100 |
* sys_get_robust_list() - Get the robust-futex list head of a task * @pid: pid of the process [zero for current task] * @head_ptr: pointer to a list-head pointer, the kernel fills it in * @len_ptr: pointer to a length field, the kernel fills in the header size |
0771dfefc [PATCH] lightweig... |
3101 |
*/ |
836f92adf [CVE-2009-0029] S... |
3102 3103 3104 |
SYSCALL_DEFINE3(get_robust_list, int, pid, struct robust_list_head __user * __user *, head_ptr, size_t __user *, len_ptr) |
0771dfefc [PATCH] lightweig... |
3105 |
{ |
ba46df984 [PATCH] __user an... |
3106 |
struct robust_list_head __user *head; |
0771dfefc [PATCH] lightweig... |
3107 |
unsigned long ret; |
bdbb776f8 futex: Do not lea... |
3108 |
struct task_struct *p; |
0771dfefc [PATCH] lightweig... |
3109 |
|
a0c1e9073 futex: runtime en... |
3110 3111 |
if (!futex_cmpxchg_enabled) return -ENOSYS; |
bdbb776f8 futex: Do not lea... |
3112 3113 3114 |
rcu_read_lock(); ret = -ESRCH; |
0771dfefc [PATCH] lightweig... |
3115 |
if (!pid) |
bdbb776f8 futex: Do not lea... |
3116 |
p = current; |
0771dfefc [PATCH] lightweig... |
3117 |
else { |
228ebcbe6 Uninline find_tas... |
3118 |
p = find_task_by_vpid(pid); |
0771dfefc [PATCH] lightweig... |
3119 3120 |
if (!p) goto err_unlock; |
0771dfefc [PATCH] lightweig... |
3121 |
} |
bdbb776f8 futex: Do not lea... |
3122 |
ret = -EPERM; |
caaee6234 ptrace: use fsuid... |
3123 |
if (!ptrace_may_access(p, PTRACE_MODE_READ_REALCREDS)) |
bdbb776f8 futex: Do not lea... |
3124 3125 3126 3127 |
goto err_unlock; head = p->robust_list; rcu_read_unlock(); |
0771dfefc [PATCH] lightweig... |
3128 3129 3130 3131 3132 |
if (put_user(sizeof(*head), len_ptr)) return -EFAULT; return put_user(head, head_ptr); err_unlock: |
aaa2a97eb [PATCH] sys_get_r... |
3133 |
rcu_read_unlock(); |
0771dfefc [PATCH] lightweig... |
3134 3135 3136 3137 3138 3139 3140 3141 |
return ret; } /* * Process a futex-list entry, check whether it's owned by the * dying task, and do notification if so: */ |
e3f2ddeac [PATCH] pi-futex:... |
3142 |
int handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi) |
0771dfefc [PATCH] lightweig... |
3143 |
{ |
7cfdaf38d futex: uninitiali... |
3144 |
u32 uval, uninitialized_var(nval), mval; |
0771dfefc [PATCH] lightweig... |
3145 |
|
8f17d3a50 [PATCH] lightweig... |
3146 3147 |
retry: if (get_user(uval, uaddr)) |
0771dfefc [PATCH] lightweig... |
3148 |
return -1; |
b488893a3 pid namespaces: c... |
3149 |
if ((uval & FUTEX_TID_MASK) == task_pid_vnr(curr)) { |
0771dfefc [PATCH] lightweig... |
3150 3151 3152 3153 3154 3155 3156 3157 3158 3159 |
/* * Ok, this dying thread is truly holding a futex * of interest. Set the OWNER_DIED bit atomically * via cmpxchg, and if the value had FUTEX_WAITERS * set, wake up a waiter (if any). (We have to do a * futex_wake() even if OWNER_DIED is already set - * to handle the rare but possible case of recursive * thread-death.) The rest of the cleanup is done in * userspace. */ |
e3f2ddeac [PATCH] pi-futex:... |
3160 |
mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED; |
6e0aa9f8a futex: Deobfuscat... |
3161 3162 3163 3164 3165 3166 3167 3168 3169 3170 3171 3172 3173 3174 |
/* * We are not holding a lock here, but we want to have * the pagefault_disable/enable() protection because * we want to handle the fault gracefully. If the * access fails we try to fault in the futex with R/W * verification via get_user_pages. get_user() above * does not guarantee R/W access. If that fails we * give up and leave the futex locked. */ if (cmpxchg_futex_value_locked(&nval, uaddr, uval, mval)) { if (fault_in_user_writeable(uaddr)) return -1; goto retry; } |
c87e2837b [PATCH] pi-futex:... |
3175 |
if (nval != uval) |
8f17d3a50 [PATCH] lightweig... |
3176 |
goto retry; |
0771dfefc [PATCH] lightweig... |
3177 |
|
e3f2ddeac [PATCH] pi-futex:... |
3178 3179 3180 3181 |
/* * Wake robust non-PI futexes here. The wakeup of * PI futexes happens in exit_pi_state(): */ |
36cf3b5c3 FUTEX: Tidy up th... |
3182 |
if (!pi && (uval & FUTEX_WAITERS)) |
c2f9f2015 futex: cleanup fs... |
3183 |
futex_wake(uaddr, 1, 1, FUTEX_BITSET_MATCH_ANY); |
0771dfefc [PATCH] lightweig... |
3184 3185 3186 3187 3188 |
} return 0; } /* |
e3f2ddeac [PATCH] pi-futex:... |
3189 3190 3191 |
* Fetch a robust-list pointer. Bit 0 signals PI futexes: */ static inline int fetch_robust_entry(struct robust_list __user **entry, |
ba46df984 [PATCH] __user an... |
3192 |
struct robust_list __user * __user *head, |
1dcc41bb0 futex: Change 3rd... |
3193 |
unsigned int *pi) |
e3f2ddeac [PATCH] pi-futex:... |
3194 3195 |
{ unsigned long uentry; |
ba46df984 [PATCH] __user an... |
3196 |
if (get_user(uentry, (unsigned long __user *)head)) |
e3f2ddeac [PATCH] pi-futex:... |
3197 |
return -EFAULT; |
ba46df984 [PATCH] __user an... |
3198 |
*entry = (void __user *)(uentry & ~1UL); |
e3f2ddeac [PATCH] pi-futex:... |
3199 3200 3201 3202 3203 3204 |
*pi = uentry & 1; return 0; } /* |
0771dfefc [PATCH] lightweig... |
3205 3206 3207 3208 3209 3210 3211 3212 |
* Walk curr->robust_list (very carefully, it's a userspace list!) * and mark any locks found there dead, and notify any waiters. * * We silently return on any sign of list-walking problem. */ void exit_robust_list(struct task_struct *curr) { struct robust_list_head __user *head = curr->robust_list; |
9f96cb1e8 robust futex thre... |
3213 |
struct robust_list __user *entry, *next_entry, *pending; |
4c115e951 futex: Address co... |
3214 3215 |
unsigned int limit = ROBUST_LIST_LIMIT, pi, pip; unsigned int uninitialized_var(next_pi); |
0771dfefc [PATCH] lightweig... |
3216 |
unsigned long futex_offset; |
9f96cb1e8 robust futex thre... |
3217 |
int rc; |
0771dfefc [PATCH] lightweig... |
3218 |
|
a0c1e9073 futex: runtime en... |
3219 3220 |
if (!futex_cmpxchg_enabled) return; |
0771dfefc [PATCH] lightweig... |
3221 3222 3223 3224 |
/* * Fetch the list head (which was registered earlier, via * sys_set_robust_list()): */ |
e3f2ddeac [PATCH] pi-futex:... |
3225 |
if (fetch_robust_entry(&entry, &head->list.next, &pi)) |
0771dfefc [PATCH] lightweig... |
3226 3227 3228 3229 3230 3231 3232 3233 3234 3235 |
return; /* * Fetch the relative futex offset: */ if (get_user(futex_offset, &head->futex_offset)) return; /* * Fetch any possibly pending lock-add first, and handle it * if it exists: */ |
e3f2ddeac [PATCH] pi-futex:... |
3236 |
if (fetch_robust_entry(&pending, &head->list_op_pending, &pip)) |
0771dfefc [PATCH] lightweig... |
3237 |
return; |
e3f2ddeac [PATCH] pi-futex:... |
3238 |
|
9f96cb1e8 robust futex thre... |
3239 |
next_entry = NULL; /* avoid warning with gcc */ |
0771dfefc [PATCH] lightweig... |
3240 3241 |
while (entry != &head->list) { /* |
9f96cb1e8 robust futex thre... |
3242 3243 3244 3245 3246 |
* Fetch the next entry in the list before calling * handle_futex_death: */ rc = fetch_robust_entry(&next_entry, &entry->next, &next_pi); /* |
0771dfefc [PATCH] lightweig... |
3247 |
* A pending lock might already be on the list, so |
c87e2837b [PATCH] pi-futex:... |
3248 |
* don't process it twice: |
0771dfefc [PATCH] lightweig... |
3249 3250 |
*/ if (entry != pending) |
ba46df984 [PATCH] __user an... |
3251 |
if (handle_futex_death((void __user *)entry + futex_offset, |
e3f2ddeac [PATCH] pi-futex:... |
3252 |
curr, pi)) |
0771dfefc [PATCH] lightweig... |
3253 |
return; |
9f96cb1e8 robust futex thre... |
3254 |
if (rc) |
0771dfefc [PATCH] lightweig... |
3255 |
return; |
9f96cb1e8 robust futex thre... |
3256 3257 |
entry = next_entry; pi = next_pi; |
0771dfefc [PATCH] lightweig... |
3258 3259 3260 3261 3262 3263 3264 3265 |
/* * Avoid excessively long or circular lists: */ if (!--limit) break; cond_resched(); } |
9f96cb1e8 robust futex thre... |
3266 3267 3268 3269 |
if (pending) handle_futex_death((void __user *)pending + futex_offset, curr, pip); |
0771dfefc [PATCH] lightweig... |
3270 |
} |
c19384b5b Make futex_wait()... |
3271 |
long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout, |
e2970f2fb [PATCH] pi-futex:... |
3272 |
u32 __user *uaddr2, u32 val2, u32 val3) |
1da177e4c Linux-2.6.12-rc2 |
3273 |
{ |
81b40539e futex: Simplify r... |
3274 |
int cmd = op & FUTEX_CMD_MASK; |
b41277dc7 futex: Replace fs... |
3275 |
unsigned int flags = 0; |
34f01cc1f FUTEX: new PRIVAT... |
3276 3277 |
if (!(op & FUTEX_PRIVATE_FLAG)) |
b41277dc7 futex: Replace fs... |
3278 |
flags |= FLAGS_SHARED; |
1da177e4c Linux-2.6.12-rc2 |
3279 |
|
b41277dc7 futex: Replace fs... |
3280 3281 |
if (op & FUTEX_CLOCK_REALTIME) { flags |= FLAGS_CLOCKRT; |
337f13046 futex: Allow FUTE... |
3282 3283 |
if (cmd != FUTEX_WAIT && cmd != FUTEX_WAIT_BITSET && \ cmd != FUTEX_WAIT_REQUEUE_PI) |
b41277dc7 futex: Replace fs... |
3284 3285 |
return -ENOSYS; } |
1da177e4c Linux-2.6.12-rc2 |
3286 |
|
34f01cc1f FUTEX: new PRIVAT... |
3287 |
switch (cmd) { |
59263b513 futex: Cover all ... |
3288 3289 3290 3291 3292 3293 3294 3295 3296 3297 |
case FUTEX_LOCK_PI: case FUTEX_UNLOCK_PI: case FUTEX_TRYLOCK_PI: case FUTEX_WAIT_REQUEUE_PI: case FUTEX_CMP_REQUEUE_PI: if (!futex_cmpxchg_enabled) return -ENOSYS; } switch (cmd) { |
1da177e4c Linux-2.6.12-rc2 |
3298 |
case FUTEX_WAIT: |
cd689985c futex: Add bitset... |
3299 3300 |
val3 = FUTEX_BITSET_MATCH_ANY; case FUTEX_WAIT_BITSET: |
81b40539e futex: Simplify r... |
3301 |
return futex_wait(uaddr, flags, val, timeout, val3); |
1da177e4c Linux-2.6.12-rc2 |
3302 |
case FUTEX_WAKE: |
cd689985c futex: Add bitset... |
3303 3304 |
val3 = FUTEX_BITSET_MATCH_ANY; case FUTEX_WAKE_BITSET: |
81b40539e futex: Simplify r... |
3305 |
return futex_wake(uaddr, flags, val, val3); |
1da177e4c Linux-2.6.12-rc2 |
3306 |
case FUTEX_REQUEUE: |
81b40539e futex: Simplify r... |
3307 |
return futex_requeue(uaddr, flags, uaddr2, val, val2, NULL, 0); |
1da177e4c Linux-2.6.12-rc2 |
3308 |
case FUTEX_CMP_REQUEUE: |
81b40539e futex: Simplify r... |
3309 |
return futex_requeue(uaddr, flags, uaddr2, val, val2, &val3, 0); |
4732efbeb [PATCH] FUTEX_WAK... |
3310 |
case FUTEX_WAKE_OP: |
81b40539e futex: Simplify r... |
3311 |
return futex_wake_op(uaddr, flags, uaddr2, val, val2, val3); |
c87e2837b [PATCH] pi-futex:... |
3312 |
case FUTEX_LOCK_PI: |
996636dda futex: Fix argume... |
3313 |
return futex_lock_pi(uaddr, flags, timeout, 0); |
c87e2837b [PATCH] pi-futex:... |
3314 |
case FUTEX_UNLOCK_PI: |
81b40539e futex: Simplify r... |
3315 |
return futex_unlock_pi(uaddr, flags); |
c87e2837b [PATCH] pi-futex:... |
3316 |
case FUTEX_TRYLOCK_PI: |
996636dda futex: Fix argume... |
3317 |
return futex_lock_pi(uaddr, flags, NULL, 1); |
52400ba94 futex: add requeu... |
3318 3319 |
case FUTEX_WAIT_REQUEUE_PI: val3 = FUTEX_BITSET_MATCH_ANY; |
81b40539e futex: Simplify r... |
3320 3321 |
return futex_wait_requeue_pi(uaddr, flags, val, timeout, val3, uaddr2); |
52400ba94 futex: add requeu... |
3322 |
case FUTEX_CMP_REQUEUE_PI: |
81b40539e futex: Simplify r... |
3323 |
return futex_requeue(uaddr, flags, uaddr2, val, val2, &val3, 1); |
1da177e4c Linux-2.6.12-rc2 |
3324 |
} |
81b40539e futex: Simplify r... |
3325 |
return -ENOSYS; |
1da177e4c Linux-2.6.12-rc2 |
3326 |
} |
17da2bd90 [CVE-2009-0029] S... |
3327 3328 3329 |
SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val, struct timespec __user *, utime, u32 __user *, uaddr2, u32, val3) |
1da177e4c Linux-2.6.12-rc2 |
3330 |
{ |
c19384b5b Make futex_wait()... |
3331 3332 |
struct timespec ts; ktime_t t, *tp = NULL; |
e2970f2fb [PATCH] pi-futex:... |
3333 |
u32 val2 = 0; |
34f01cc1f FUTEX: new PRIVAT... |
3334 |
int cmd = op & FUTEX_CMD_MASK; |
1da177e4c Linux-2.6.12-rc2 |
3335 |
|
cd689985c futex: Add bitset... |
3336 |
if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI || |
52400ba94 futex: add requeu... |
3337 3338 |
cmd == FUTEX_WAIT_BITSET || cmd == FUTEX_WAIT_REQUEUE_PI)) { |
ab51fbab3 futex: Fault/erro... |
3339 3340 |
if (unlikely(should_fail_futex(!(op & FUTEX_PRIVATE_FLAG)))) return -EFAULT; |
c19384b5b Make futex_wait()... |
3341 |
if (copy_from_user(&ts, utime, sizeof(ts)) != 0) |
1da177e4c Linux-2.6.12-rc2 |
3342 |
return -EFAULT; |
c19384b5b Make futex_wait()... |
3343 |
if (!timespec_valid(&ts)) |
9741ef964 [PATCH] futex: ch... |
3344 |
return -EINVAL; |
c19384b5b Make futex_wait()... |
3345 3346 |
t = timespec_to_ktime(ts); |
34f01cc1f FUTEX: new PRIVAT... |
3347 |
if (cmd == FUTEX_WAIT) |
5a7780e72 hrtimer: check re... |
3348 |
t = ktime_add_safe(ktime_get(), t); |
c19384b5b Make futex_wait()... |
3349 |
tp = &t; |
1da177e4c Linux-2.6.12-rc2 |
3350 3351 |
} /* |
52400ba94 futex: add requeu... |
3352 |
* requeue parameter in 'utime' if cmd == FUTEX_*_REQUEUE_*. |
f54f09861 futex: pass nr_wa... |
3353 |
* number of waiters to wake in 'utime' if cmd == FUTEX_WAKE_OP. |
1da177e4c Linux-2.6.12-rc2 |
3354 |
*/ |
f54f09861 futex: pass nr_wa... |
3355 |
if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE || |
ba9c22f2c futex: remove FUT... |
3356 |
cmd == FUTEX_CMP_REQUEUE_PI || cmd == FUTEX_WAKE_OP) |
e2970f2fb [PATCH] pi-futex:... |
3357 |
val2 = (u32) (unsigned long) utime; |
1da177e4c Linux-2.6.12-rc2 |
3358 |
|
c19384b5b Make futex_wait()... |
3359 |
return do_futex(uaddr, op, val, tp, uaddr2, val2, val3); |
1da177e4c Linux-2.6.12-rc2 |
3360 |
} |
03b8c7b62 futex: Allow arch... |
3361 |
static void __init futex_detect_cmpxchg(void) |
1da177e4c Linux-2.6.12-rc2 |
3362 |
{ |
03b8c7b62 futex: Allow arch... |
3363 |
#ifndef CONFIG_HAVE_FUTEX_CMPXCHG |
a0c1e9073 futex: runtime en... |
3364 |
u32 curval; |
03b8c7b62 futex: Allow arch... |
3365 3366 3367 3368 3369 3370 3371 3372 3373 3374 3375 3376 3377 3378 3379 3380 3381 3382 |
/* * This will fail and we want it. Some arch implementations do * runtime detection of the futex_atomic_cmpxchg_inatomic() * functionality. We want to know that before we call in any * of the complex code paths. Also we want to prevent * registration of robust lists in that case. NULL is * guaranteed to fault and we get -EFAULT on functional * implementation, the non-functional ones will return * -ENOSYS. */ if (cmpxchg_futex_value_locked(&curval, NULL, 0, 0) == -EFAULT) futex_cmpxchg_enabled = 1; #endif } static int __init futex_init(void) { |
63b1a8169 futexes: Fix fute... |
3383 |
unsigned int futex_shift; |
a52b89ebb futexes: Increase... |
3384 3385 3386 3387 3388 3389 3390 3391 3392 3393 3394 |
unsigned long i; #if CONFIG_BASE_SMALL futex_hashsize = 16; #else futex_hashsize = roundup_pow_of_two(256 * num_possible_cpus()); #endif futex_queues = alloc_large_system_hash("futex", sizeof(*futex_queues), futex_hashsize, 0, futex_hashsize < 256 ? HASH_SMALL : 0, |
63b1a8169 futexes: Fix fute... |
3395 3396 3397 |
&futex_shift, NULL, futex_hashsize, futex_hashsize); futex_hashsize = 1UL << futex_shift; |
03b8c7b62 futex: Allow arch... |
3398 3399 |
futex_detect_cmpxchg(); |
a0c1e9073 futex: runtime en... |
3400 |
|
a52b89ebb futexes: Increase... |
3401 |
for (i = 0; i < futex_hashsize; i++) { |
11d4616bd futex: revert bac... |
3402 |
atomic_set(&futex_queues[i].waiters, 0); |
732375c6a plist: Remove the... |
3403 |
plist_head_init(&futex_queues[i].chain); |
3e4ab747e futex: fix init o... |
3404 3405 |
spin_lock_init(&futex_queues[i].lock); } |
1da177e4c Linux-2.6.12-rc2 |
3406 3407 |
return 0; } |
25f71d1c3 futex: Move futex... |
3408 |
core_initcall(futex_init); |