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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 <asm/futex.h> |
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|
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#include "rtmutex_common.h" |
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int __read_mostly futex_cmpxchg_enabled; |
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#define FUTEX_HASHBITS (CONFIG_BASE_SMALL ? 4 : 8) /* |
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* Futex flags used to encode options to functions and preserve them across * restarts. */ #define FLAGS_SHARED 0x01 #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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/** * 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 * * We use this hashed waitqueue, instead of a normal wait_queue_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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}; |
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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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spinlock_t lock; struct plist_head chain; |
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}; static struct futex_hash_bucket futex_queues[1<<FUTEX_HASHBITS]; |
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/* * We hash on the keys returned from get_futex_key (see below). */ 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); return &futex_queues[hash & ((1 << FUTEX_HASHBITS)-1)]; } /* * 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; switch (key->both.offset & (FUT_OFF_INODE|FUT_OFF_MMSHARED)) { case FUT_OFF_INODE: |
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ihold(key->shared.inode); |
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break; case FUT_OFF_MMSHARED: atomic_inc(&key->private.mm->mm_count); break; } } /* * Drop a reference to the resource addressed by a key. * The hash bucket spinlock must not be held. */ 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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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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* * Returns a negative error code or 0 * The key words are stored in *key on success. |
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* |
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* For shared mappings, it's (page->index, vma->vm_file->f_path.dentry->d_inode, |
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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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static int |
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get_futex_key(u32 __user *uaddr, int fshared, union futex_key *key, int rw) |
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{ |
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unsigned long address = (unsigned long)uaddr; |
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struct mm_struct *mm = current->mm; |
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struct page *page, *page_head; |
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int err, ro = 0; |
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/* * The futex address must be "naturally" aligned. */ |
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key->both.offset = address % PAGE_SIZE; |
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if (unlikely((address % sizeof(u32)) != 0)) |
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return -EINVAL; |
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address -= key->both.offset; |
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/* |
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* 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) { |
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if (unlikely(!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))) |
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return -EFAULT; key->private.mm = mm; key->private.address = address; |
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get_futex_key_refs(key); |
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return 0; } |
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|
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again: |
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err = get_user_pages_fast(address, 1, 1, &page); |
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/* * 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; } |
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if (err < 0) return err; |
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else err = 0; |
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|
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#ifdef CONFIG_TRANSPARENT_HUGEPAGE page_head = page; if (unlikely(PageTail(page))) { |
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put_page(page); |
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/* serialize against __split_huge_page_splitting() */ local_irq_disable(); if (likely(__get_user_pages_fast(address, 1, 1, &page) == 1)) { page_head = compound_head(page); /* * page_head is valid pointer but we must pin * it before taking the PG_lock and/or * PG_compound_lock. The moment we re-enable * irqs __split_huge_page_splitting() can * return and the head page can be freed from * under us. We can't take the PG_lock and/or * PG_compound_lock on a page that could be * freed from under us. */ if (page != page_head) { get_page(page_head); put_page(page); } local_irq_enable(); } else { local_irq_enable(); goto again; } } #else page_head = compound_head(page); if (page != page_head) { get_page(page_head); put_page(page); } #endif lock_page(page_head); |
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/* * If page_head->mapping is NULL, then it cannot be a PageAnon * 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: * an unlikely race, but we do need to retry for page_head->mapping. */ |
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if (!page_head->mapping) { |
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int shmem_swizzled = PageSwapCache(page_head); |
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unlock_page(page_head); put_page(page_head); |
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if (shmem_swizzled) goto again; return -EFAULT; |
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} |
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/* * Private mappings are handled in a simple way. * * NOTE: When userspace waits on a MAP_SHARED mapping, even if * it's a read-only handle, it's expected that futexes attach to |
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* the object not the particular process. |
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*/ |
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if (PageAnon(page_head)) { |
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/* * A RO anonymous page will never change and thus doesn't make * sense for futex operations. */ if (ro) { err = -EFAULT; goto out; } |
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key->both.offset |= FUT_OFF_MMSHARED; /* ref taken on mm */ |
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key->private.mm = mm; |
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key->private.address = address; |
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} else { key->both.offset |= FUT_OFF_INODE; /* inode-based key */ |
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key->shared.inode = page_head->mapping->host; key->shared.pgoff = page_head->index; |
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} |
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get_futex_key_refs(key); |
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|
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out: |
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unlock_page(page_head); put_page(page_head); |
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return err; |
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} |
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static inline void put_futex_key(union futex_key *key) |
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{ |
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drop_futex_key_refs(key); |
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} |
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/** * fault_in_user_writeable() - Fault in user address and verify RW access |
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* @uaddr: pointer to faulting user space address * * Slow path to fixup the fault we just took in the atomic write * access to @uaddr. * |
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* We have no generic implementation of a non-destructive write to the |
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* 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) { |
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struct mm_struct *mm = current->mm; int ret; down_read(&mm->mmap_sem); |
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ret = fixup_user_fault(current, mm, (unsigned long)uaddr, FAULT_FLAG_WRITE); |
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up_read(&mm->mmap_sem); |
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return ret < 0 ? ret : 0; } |
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/** * futex_top_waiter() - Return the highest priority waiter on a futex |
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* @hb: the hash bucket the futex_q's reside in * @key: the futex key (to distinguish it from other futex futex_q's) |
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* * 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; } |
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static int cmpxchg_futex_value_locked(u32 *curval, u32 __user *uaddr, u32 uval, u32 newval) |
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{ |
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int ret; |
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pagefault_disable(); |
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ret = futex_atomic_cmpxchg_inatomic(curval, uaddr, uval, newval); |
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pagefault_enable(); |
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return ret; |
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} static int get_futex_value_locked(u32 *dest, u32 __user *from) |
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{ int ret; |
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pagefault_disable(); |
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ret = __copy_from_user_inatomic(dest, from, sizeof(u32)); |
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pagefault_enable(); |
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return ret ? -EFAULT : 0; } |
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/* * PI code: */ static int refill_pi_state_cache(void) { struct futex_pi_state *pi_state; if (likely(current->pi_state_cache)) return 0; |
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pi_state = kzalloc(sizeof(*pi_state), GFP_KERNEL); |
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if (!pi_state) return -ENOMEM; |
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INIT_LIST_HEAD(&pi_state->list); /* pi_mutex gets initialized later */ pi_state->owner = NULL; atomic_set(&pi_state->refcount, 1); |
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pi_state->key = FUTEX_KEY_INIT; |
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current->pi_state_cache = pi_state; return 0; } static struct futex_pi_state * alloc_pi_state(void) { struct futex_pi_state *pi_state = current->pi_state_cache; WARN_ON(!pi_state); current->pi_state_cache = NULL; return pi_state; } static void free_pi_state(struct futex_pi_state *pi_state) { 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) { |
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raw_spin_lock_irq(&pi_state->owner->pi_lock); |
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list_del_init(&pi_state->list); |
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raw_spin_unlock_irq(&pi_state->owner->pi_lock); |
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477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 |
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. */ static struct task_struct * futex_find_get_task(pid_t pid) { struct task_struct *p; |
d359b549b [PATCH] futex_fin... |
502 |
rcu_read_lock(); |
228ebcbe6 Uninline find_tas... |
503 |
p = find_task_by_vpid(pid); |
7a0ea09ad futex: futex_find... |
504 505 |
if (p) get_task_struct(p); |
a06381fec FUTEX: Restore th... |
506 |
|
d359b549b [PATCH] futex_fin... |
507 |
rcu_read_unlock(); |
c87e2837b [PATCH] pi-futex:... |
508 509 510 511 512 513 514 515 516 517 518 |
return p; } /* * 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:... |
519 520 |
struct list_head *next, *head = &curr->pi_state_list; struct futex_pi_state *pi_state; |
627371d73 [PATCH] pi-futex:... |
521 |
struct futex_hash_bucket *hb; |
38d47c1b7 futex: rely on ge... |
522 |
union futex_key key = FUTEX_KEY_INIT; |
c87e2837b [PATCH] pi-futex:... |
523 |
|
a0c1e9073 futex: runtime en... |
524 525 |
if (!futex_cmpxchg_enabled) return; |
c87e2837b [PATCH] pi-futex:... |
526 527 528 |
/* * We are a ZOMBIE and nobody can enqueue itself on * pi_state_list anymore, but we have to be careful |
627371d73 [PATCH] pi-futex:... |
529 |
* versus waiters unqueueing themselves: |
c87e2837b [PATCH] pi-futex:... |
530 |
*/ |
1d6154825 sched: Convert pi... |
531 |
raw_spin_lock_irq(&curr->pi_lock); |
c87e2837b [PATCH] pi-futex:... |
532 533 534 535 536 |
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:... |
537 |
hb = hash_futex(&key); |
1d6154825 sched: Convert pi... |
538 |
raw_spin_unlock_irq(&curr->pi_lock); |
c87e2837b [PATCH] pi-futex:... |
539 |
|
c87e2837b [PATCH] pi-futex:... |
540 |
spin_lock(&hb->lock); |
1d6154825 sched: Convert pi... |
541 |
raw_spin_lock_irq(&curr->pi_lock); |
627371d73 [PATCH] pi-futex:... |
542 543 544 545 |
/* * We dropped the pi-lock, so re-check whether this * task still owns the PI-state: */ |
c87e2837b [PATCH] pi-futex:... |
546 547 548 549 |
if (head->next != next) { spin_unlock(&hb->lock); continue; } |
c87e2837b [PATCH] pi-futex:... |
550 |
WARN_ON(pi_state->owner != curr); |
627371d73 [PATCH] pi-futex:... |
551 552 |
WARN_ON(list_empty(&pi_state->list)); list_del_init(&pi_state->list); |
c87e2837b [PATCH] pi-futex:... |
553 |
pi_state->owner = NULL; |
1d6154825 sched: Convert pi... |
554 |
raw_spin_unlock_irq(&curr->pi_lock); |
c87e2837b [PATCH] pi-futex:... |
555 556 557 558 |
rt_mutex_unlock(&pi_state->pi_mutex); spin_unlock(&hb->lock); |
1d6154825 sched: Convert pi... |
559 |
raw_spin_lock_irq(&curr->pi_lock); |
c87e2837b [PATCH] pi-futex:... |
560 |
} |
1d6154825 sched: Convert pi... |
561 |
raw_spin_unlock_irq(&curr->pi_lock); |
c87e2837b [PATCH] pi-futex:... |
562 563 564 |
} static int |
d0aa7a70b futex_requeue_pi ... |
565 566 |
lookup_pi_state(u32 uval, struct futex_hash_bucket *hb, union futex_key *key, struct futex_pi_state **ps) |
c87e2837b [PATCH] pi-futex:... |
567 568 569 |
{ struct futex_pi_state *pi_state = NULL; struct futex_q *this, *next; |
ec92d0829 futex priority ba... |
570 |
struct plist_head *head; |
c87e2837b [PATCH] pi-futex:... |
571 |
struct task_struct *p; |
778e9a9c3 pi-futex: fix exi... |
572 |
pid_t pid = uval & FUTEX_TID_MASK; |
c87e2837b [PATCH] pi-futex:... |
573 574 |
head = &hb->chain; |
ec92d0829 futex priority ba... |
575 |
plist_for_each_entry_safe(this, next, head, list) { |
d0aa7a70b futex_requeue_pi ... |
576 |
if (match_futex(&this->key, key)) { |
c87e2837b [PATCH] pi-futex:... |
577 578 579 580 581 |
/* * Another waiter already exists - bump up * the refcount and return its pi_state: */ pi_state = this->pi_state; |
06a9ec291 [PATCH] pi-futex:... |
582 |
/* |
fb62db2ba futex: Fix kernel... |
583 |
* Userspace might have messed up non-PI and PI futexes |
06a9ec291 [PATCH] pi-futex:... |
584 585 586 |
*/ if (unlikely(!pi_state)) return -EINVAL; |
627371d73 [PATCH] pi-futex:... |
587 |
WARN_ON(!atomic_read(&pi_state->refcount)); |
59647b6ac futex: Handle fut... |
588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 |
/* * When pi_state->owner is NULL then the owner died * and another waiter is on the fly. pi_state->owner * is fixed up by the task which acquires * pi_state->rt_mutex. * * We do not check for pid == 0 which can happen when * the owner died and robust_list_exit() cleared the * TID. */ if (pid && pi_state->owner) { /* * Bail out if user space manipulated the * futex value. */ if (pid != task_pid_vnr(pi_state->owner)) return -EINVAL; } |
627371d73 [PATCH] pi-futex:... |
607 |
|
c87e2837b [PATCH] pi-futex:... |
608 |
atomic_inc(&pi_state->refcount); |
d0aa7a70b futex_requeue_pi ... |
609 |
*ps = pi_state; |
c87e2837b [PATCH] pi-futex:... |
610 611 612 613 614 615 |
return 0; } } /* |
e3f2ddeac [PATCH] pi-futex:... |
616 |
* We are the first waiter - try to look up the real owner and attach |
778e9a9c3 pi-futex: fix exi... |
617 |
* the new pi_state to it, but bail out when TID = 0 |
c87e2837b [PATCH] pi-futex:... |
618 |
*/ |
778e9a9c3 pi-futex: fix exi... |
619 |
if (!pid) |
e3f2ddeac [PATCH] pi-futex:... |
620 |
return -ESRCH; |
c87e2837b [PATCH] pi-futex:... |
621 |
p = futex_find_get_task(pid); |
7a0ea09ad futex: futex_find... |
622 623 |
if (!p) return -ESRCH; |
778e9a9c3 pi-futex: fix exi... |
624 625 626 627 628 629 630 |
/* * 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... |
631 |
raw_spin_lock_irq(&p->pi_lock); |
778e9a9c3 pi-futex: fix exi... |
632 633 634 635 636 637 638 |
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... |
639 |
raw_spin_unlock_irq(&p->pi_lock); |
778e9a9c3 pi-futex: fix exi... |
640 641 642 |
put_task_struct(p); return ret; } |
c87e2837b [PATCH] pi-futex:... |
643 644 645 646 647 648 649 650 651 652 |
pi_state = alloc_pi_state(); /* * Initialize the pi_mutex in locked state and make 'p' * 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 ... |
653 |
pi_state->key = *key; |
c87e2837b [PATCH] pi-futex:... |
654 |
|
627371d73 [PATCH] pi-futex:... |
655 |
WARN_ON(!list_empty(&pi_state->list)); |
c87e2837b [PATCH] pi-futex:... |
656 657 |
list_add(&pi_state->list, &p->pi_state_list); pi_state->owner = p; |
1d6154825 sched: Convert pi... |
658 |
raw_spin_unlock_irq(&p->pi_lock); |
c87e2837b [PATCH] pi-futex:... |
659 660 |
put_task_struct(p); |
d0aa7a70b futex_requeue_pi ... |
661 |
*ps = pi_state; |
c87e2837b [PATCH] pi-futex:... |
662 663 664 |
return 0; } |
1a52084d0 futex: split out ... |
665 |
/** |
d96ee56ce futex: Make funct... |
666 |
* futex_lock_pi_atomic() - Atomic work required to acquire a pi aware futex |
bab5bc9e8 futex: fixup unlo... |
667 668 669 670 671 672 673 674 |
* @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 ... |
675 676 677 678 679 680 681 682 683 684 685 |
* * Returns: * 0 - ready to wait * 1 - acquired the lock * <0 - error * * 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... |
686 |
struct task_struct *task, int set_waiters) |
1a52084d0 futex: split out ... |
687 688 |
{ int lock_taken, ret, ownerdied = 0; |
c0c9ed150 futex: Avoid redu... |
689 |
u32 uval, newval, curval, vpid = task_pid_vnr(task); |
1a52084d0 futex: split out ... |
690 691 692 693 694 695 696 697 698 |
retry: ret = lock_taken = 0; /* * To avoid races, we attempt to take the lock here again * (by doing a 0 -> TID atomic cmpxchg), while holding all * the locks. It will most likely not succeed. */ |
c0c9ed150 futex: Avoid redu... |
699 |
newval = vpid; |
bab5bc9e8 futex: fixup unlo... |
700 701 |
if (set_waiters) newval |= FUTEX_WAITERS; |
1a52084d0 futex: split out ... |
702 |
|
37a9d912b futex: Sanitize c... |
703 |
if (unlikely(cmpxchg_futex_value_locked(&curval, uaddr, 0, newval))) |
1a52084d0 futex: split out ... |
704 705 706 707 708 |
return -EFAULT; /* * Detect deadlocks. */ |
c0c9ed150 futex: Avoid redu... |
709 |
if ((unlikely((curval & FUTEX_TID_MASK) == vpid))) |
1a52084d0 futex: split out ... |
710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 |
return -EDEADLK; /* * Surprise - we got the lock. Just return to userspace: */ if (unlikely(!curval)) return 1; uval = curval; /* * Set the FUTEX_WAITERS flag, so the owner will know it has someone * to wake at the next unlock. */ newval = curval | FUTEX_WAITERS; /* * There are two cases, where a futex might have no owner (the * owner TID is 0): OWNER_DIED. We take over the futex in this * case. We also do an unconditional take over, when the owner * of the futex died. * * This is safe as we are protected by the hash bucket lock ! */ if (unlikely(ownerdied || !(curval & FUTEX_TID_MASK))) { /* Keep the OWNER_DIED bit */ |
c0c9ed150 futex: Avoid redu... |
736 |
newval = (curval & ~FUTEX_TID_MASK) | vpid; |
1a52084d0 futex: split out ... |
737 738 739 |
ownerdied = 0; lock_taken = 1; } |
37a9d912b futex: Sanitize c... |
740 |
if (unlikely(cmpxchg_futex_value_locked(&curval, uaddr, uval, newval))) |
1a52084d0 futex: split out ... |
741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 |
return -EFAULT; if (unlikely(curval != uval)) goto retry; /* * We took the lock due to owner died take over. */ if (unlikely(lock_taken)) return 1; /* * We dont have the lock. Look up the PI state (or create it if * we are the first waiter): */ ret = lookup_pi_state(uval, hb, key, ps); if (unlikely(ret)) { switch (ret) { case -ESRCH: /* * No owner found for this futex. Check if the * OWNER_DIED bit is set to figure out whether * this is a robust futex or not. */ if (get_futex_value_locked(&curval, uaddr)) return -EFAULT; /* * We simply start over in case of a robust * futex. The code above will take the futex * and return happy. */ if (curval & FUTEX_OWNER_DIED) { ownerdied = 1; goto retry; } default: break; } } return ret; } |
2e12978a9 futex,plist: Pass... |
784 785 786 787 788 789 790 791 792 |
/** * __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... |
793 794 |
if (WARN_ON_SMP(!q->lock_ptr || !spin_is_locked(q->lock_ptr)) || WARN_ON(plist_node_empty(&q->list))) |
2e12978a9 futex,plist: Pass... |
795 796 797 798 799 |
return; hb = container_of(q->lock_ptr, struct futex_hash_bucket, lock); plist_del(&q->list, &hb->chain); } |
c87e2837b [PATCH] pi-futex:... |
800 |
/* |
1da177e4c Linux-2.6.12-rc2 |
801 802 803 804 805 |
* The hash bucket lock must be held when this is called. * Afterwards, the futex_q must not be accessed. */ static void wake_futex(struct futex_q *q) { |
f1a11e057 futex: remove the... |
806 |
struct task_struct *p = q->task; |
1da177e4c Linux-2.6.12-rc2 |
807 |
/* |
f1a11e057 futex: remove the... |
808 |
* We set q->lock_ptr = NULL _before_ we wake up the task. If |
fb62db2ba futex: Fix kernel... |
809 810 |
* a non-futex wake up happens on another CPU then the task * might exit and p would dereference a non-existing task |
f1a11e057 futex: remove the... |
811 812 |
* struct. Prevent this by holding a reference on p across the * wake up. |
1da177e4c Linux-2.6.12-rc2 |
813 |
*/ |
f1a11e057 futex: remove the... |
814 |
get_task_struct(p); |
2e12978a9 futex,plist: Pass... |
815 |
__unqueue_futex(q); |
1da177e4c Linux-2.6.12-rc2 |
816 |
/* |
f1a11e057 futex: remove the... |
817 818 819 820 |
* The waiting task can free the futex_q as soon as * q->lock_ptr = NULL is written, without taking any locks. A * memory barrier is required here to prevent the following * store to lock_ptr from getting ahead of the plist_del. |
1da177e4c Linux-2.6.12-rc2 |
821 |
*/ |
ccdea2f88 [PATCH] futex: re... |
822 |
smp_wmb(); |
1da177e4c Linux-2.6.12-rc2 |
823 |
q->lock_ptr = NULL; |
f1a11e057 futex: remove the... |
824 825 826 |
wake_up_state(p, TASK_NORMAL); put_task_struct(p); |
1da177e4c Linux-2.6.12-rc2 |
827 |
} |
c87e2837b [PATCH] pi-futex:... |
828 829 830 831 |
static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this) { struct task_struct *new_owner; struct futex_pi_state *pi_state = this->pi_state; |
7cfdaf38d futex: uninitiali... |
832 |
u32 uninitialized_var(curval), newval; |
c87e2837b [PATCH] pi-futex:... |
833 834 835 |
if (!pi_state) return -EINVAL; |
51246bfd1 futex: Handle use... |
836 837 838 839 840 841 |
/* * 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) return -EINVAL; |
d209d74d5 rtmutes: Convert ... |
842 |
raw_spin_lock(&pi_state->pi_mutex.wait_lock); |
c87e2837b [PATCH] pi-futex:... |
843 844 845 |
new_owner = rt_mutex_next_owner(&pi_state->pi_mutex); /* |
f123c98e7 rtmutex: Fix comm... |
846 847 848 |
* It is possible that the next waiter (the one that brought * this owner to the kernel) timed out and is no longer * waiting on the lock. |
c87e2837b [PATCH] pi-futex:... |
849 850 851 852 853 854 855 856 857 |
*/ if (!new_owner) new_owner = this->task; /* * We pass it to the next owner. (The WAITERS bit is always * kept enabled while there is PI state around. We must also * preserve the owner died bit.) */ |
e3f2ddeac [PATCH] pi-futex:... |
858 |
if (!(uval & FUTEX_OWNER_DIED)) { |
778e9a9c3 pi-futex: fix exi... |
859 |
int ret = 0; |
b488893a3 pid namespaces: c... |
860 |
newval = FUTEX_WAITERS | task_pid_vnr(new_owner); |
e3f2ddeac [PATCH] pi-futex:... |
861 |
|
37a9d912b futex: Sanitize c... |
862 |
if (cmpxchg_futex_value_locked(&curval, uaddr, uval, newval)) |
778e9a9c3 pi-futex: fix exi... |
863 |
ret = -EFAULT; |
cde898fa8 futex: correctly ... |
864 |
else if (curval != uval) |
778e9a9c3 pi-futex: fix exi... |
865 866 |
ret = -EINVAL; if (ret) { |
d209d74d5 rtmutes: Convert ... |
867 |
raw_spin_unlock(&pi_state->pi_mutex.wait_lock); |
778e9a9c3 pi-futex: fix exi... |
868 869 |
return ret; } |
e3f2ddeac [PATCH] pi-futex:... |
870 |
} |
c87e2837b [PATCH] pi-futex:... |
871 |
|
1d6154825 sched: Convert pi... |
872 |
raw_spin_lock_irq(&pi_state->owner->pi_lock); |
627371d73 [PATCH] pi-futex:... |
873 874 |
WARN_ON(list_empty(&pi_state->list)); list_del_init(&pi_state->list); |
1d6154825 sched: Convert pi... |
875 |
raw_spin_unlock_irq(&pi_state->owner->pi_lock); |
627371d73 [PATCH] pi-futex:... |
876 |
|
1d6154825 sched: Convert pi... |
877 |
raw_spin_lock_irq(&new_owner->pi_lock); |
627371d73 [PATCH] pi-futex:... |
878 |
WARN_ON(!list_empty(&pi_state->list)); |
c87e2837b [PATCH] pi-futex:... |
879 880 |
list_add(&pi_state->list, &new_owner->pi_state_list); pi_state->owner = new_owner; |
1d6154825 sched: Convert pi... |
881 |
raw_spin_unlock_irq(&new_owner->pi_lock); |
627371d73 [PATCH] pi-futex:... |
882 |
|
d209d74d5 rtmutes: Convert ... |
883 |
raw_spin_unlock(&pi_state->pi_mutex.wait_lock); |
c87e2837b [PATCH] pi-futex:... |
884 885 886 887 888 889 890 |
rt_mutex_unlock(&pi_state->pi_mutex); return 0; } static int unlock_futex_pi(u32 __user *uaddr, u32 uval) { |
7cfdaf38d futex: uninitiali... |
891 |
u32 uninitialized_var(oldval); |
c87e2837b [PATCH] pi-futex:... |
892 893 894 895 896 |
/* * There is no waiter, so we unlock the futex. The owner died * bit has not to be preserved here. We are the owner: */ |
37a9d912b futex: Sanitize c... |
897 898 |
if (cmpxchg_futex_value_locked(&oldval, uaddr, uval, 0)) return -EFAULT; |
c87e2837b [PATCH] pi-futex:... |
899 900 901 902 903 |
if (oldval != uval) return -EAGAIN; return 0; } |
1da177e4c Linux-2.6.12-rc2 |
904 |
/* |
8b8f319fc [PATCH] lockdep: ... |
905 906 907 908 909 910 911 912 913 914 915 916 917 918 |
* 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... |
919 920 921 |
static inline void double_unlock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2) { |
f061d3515 futex: remove the... |
922 |
spin_unlock(&hb1->lock); |
88f502fed futex: remove the... |
923 924 |
if (hb1 != hb2) spin_unlock(&hb2->lock); |
5eb3dc62f futex: add double... |
925 |
} |
8b8f319fc [PATCH] lockdep: ... |
926 |
/* |
b2d0994b1 futex: update fut... |
927 |
* Wake up waiters matching bitset queued on this futex (uaddr). |
1da177e4c Linux-2.6.12-rc2 |
928 |
*/ |
b41277dc7 futex: Replace fs... |
929 930 |
static int futex_wake(u32 __user *uaddr, unsigned int flags, int nr_wake, u32 bitset) |
1da177e4c Linux-2.6.12-rc2 |
931 |
{ |
e2970f2fb [PATCH] pi-futex:... |
932 |
struct futex_hash_bucket *hb; |
1da177e4c Linux-2.6.12-rc2 |
933 |
struct futex_q *this, *next; |
ec92d0829 futex priority ba... |
934 |
struct plist_head *head; |
38d47c1b7 futex: rely on ge... |
935 |
union futex_key key = FUTEX_KEY_INIT; |
1da177e4c Linux-2.6.12-rc2 |
936 |
int ret; |
cd689985c futex: Add bitset... |
937 938 |
if (!bitset) return -EINVAL; |
9ea71503a futex: Fix regres... |
939 |
ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &key, VERIFY_READ); |
1da177e4c Linux-2.6.12-rc2 |
940 941 |
if (unlikely(ret != 0)) goto out; |
e2970f2fb [PATCH] pi-futex:... |
942 943 944 |
hb = hash_futex(&key); spin_lock(&hb->lock); head = &hb->chain; |
1da177e4c Linux-2.6.12-rc2 |
945 |
|
ec92d0829 futex priority ba... |
946 |
plist_for_each_entry_safe(this, next, head, list) { |
1da177e4c Linux-2.6.12-rc2 |
947 |
if (match_futex (&this->key, &key)) { |
52400ba94 futex: add requeu... |
948 |
if (this->pi_state || this->rt_waiter) { |
ed6f7b10e [PATCH] pi-futex:... |
949 950 951 |
ret = -EINVAL; break; } |
cd689985c futex: Add bitset... |
952 953 954 955 |
/* Check if one of the bits is set in both bitsets */ if (!(this->bitset & bitset)) continue; |
1da177e4c Linux-2.6.12-rc2 |
956 957 958 959 960 |
wake_futex(this); if (++ret >= nr_wake) break; } } |
e2970f2fb [PATCH] pi-futex:... |
961 |
spin_unlock(&hb->lock); |
ae791a2d2 futex: Cleanup st... |
962 |
put_futex_key(&key); |
42d35d48c futex: make futex... |
963 |
out: |
1da177e4c Linux-2.6.12-rc2 |
964 965 966 967 |
return ret; } /* |
4732efbeb [PATCH] FUTEX_WAK... |
968 969 970 |
* Wake up all waiters hashed on the physical page that is mapped * to this virtual address: */ |
e2970f2fb [PATCH] pi-futex:... |
971 |
static int |
b41277dc7 futex: Replace fs... |
972 |
futex_wake_op(u32 __user *uaddr1, unsigned int flags, u32 __user *uaddr2, |
e2970f2fb [PATCH] pi-futex:... |
973 |
int nr_wake, int nr_wake2, int op) |
4732efbeb [PATCH] FUTEX_WAK... |
974 |
{ |
38d47c1b7 futex: rely on ge... |
975 |
union futex_key key1 = FUTEX_KEY_INIT, key2 = FUTEX_KEY_INIT; |
e2970f2fb [PATCH] pi-futex:... |
976 |
struct futex_hash_bucket *hb1, *hb2; |
ec92d0829 futex priority ba... |
977 |
struct plist_head *head; |
4732efbeb [PATCH] FUTEX_WAK... |
978 |
struct futex_q *this, *next; |
e4dc5b7a3 futex: clean up f... |
979 |
int ret, op_ret; |
4732efbeb [PATCH] FUTEX_WAK... |
980 |
|
e4dc5b7a3 futex: clean up f... |
981 |
retry: |
9ea71503a futex: Fix regres... |
982 |
ret = get_futex_key(uaddr1, flags & FLAGS_SHARED, &key1, VERIFY_READ); |
4732efbeb [PATCH] FUTEX_WAK... |
983 984 |
if (unlikely(ret != 0)) goto out; |
9ea71503a futex: Fix regres... |
985 |
ret = get_futex_key(uaddr2, flags & FLAGS_SHARED, &key2, VERIFY_WRITE); |
4732efbeb [PATCH] FUTEX_WAK... |
986 |
if (unlikely(ret != 0)) |
42d35d48c futex: make futex... |
987 |
goto out_put_key1; |
4732efbeb [PATCH] FUTEX_WAK... |
988 |
|
e2970f2fb [PATCH] pi-futex:... |
989 990 |
hb1 = hash_futex(&key1); hb2 = hash_futex(&key2); |
4732efbeb [PATCH] FUTEX_WAK... |
991 |
|
e4dc5b7a3 futex: clean up f... |
992 |
retry_private: |
eaaea8036 futex: Fix lockin... |
993 |
double_lock_hb(hb1, hb2); |
e2970f2fb [PATCH] pi-futex:... |
994 |
op_ret = futex_atomic_op_inuser(op, uaddr2); |
4732efbeb [PATCH] FUTEX_WAK... |
995 |
if (unlikely(op_ret < 0)) { |
4732efbeb [PATCH] FUTEX_WAK... |
996 |
|
5eb3dc62f futex: add double... |
997 |
double_unlock_hb(hb1, hb2); |
4732efbeb [PATCH] FUTEX_WAK... |
998 |
|
7ee1dd3fe [PATCH] FRV: Make... |
999 |
#ifndef CONFIG_MMU |
e2970f2fb [PATCH] pi-futex:... |
1000 1001 1002 1003 |
/* * 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... |
1004 |
ret = op_ret; |
42d35d48c futex: make futex... |
1005 |
goto out_put_keys; |
7ee1dd3fe [PATCH] FRV: Make... |
1006 |
#endif |
796f8d9b9 [PATCH] FUTEX_WAK... |
1007 1008 |
if (unlikely(op_ret != -EFAULT)) { ret = op_ret; |
42d35d48c futex: make futex... |
1009 |
goto out_put_keys; |
796f8d9b9 [PATCH] FUTEX_WAK... |
1010 |
} |
d0725992c futex: Fix the wr... |
1011 |
ret = fault_in_user_writeable(uaddr2); |
4732efbeb [PATCH] FUTEX_WAK... |
1012 |
if (ret) |
de87fcc12 futex: additional... |
1013 |
goto out_put_keys; |
4732efbeb [PATCH] FUTEX_WAK... |
1014 |
|
b41277dc7 futex: Replace fs... |
1015 |
if (!(flags & FLAGS_SHARED)) |
e4dc5b7a3 futex: clean up f... |
1016 |
goto retry_private; |
ae791a2d2 futex: Cleanup st... |
1017 1018 |
put_futex_key(&key2); put_futex_key(&key1); |
e4dc5b7a3 futex: clean up f... |
1019 |
goto retry; |
4732efbeb [PATCH] FUTEX_WAK... |
1020 |
} |
e2970f2fb [PATCH] pi-futex:... |
1021 |
head = &hb1->chain; |
4732efbeb [PATCH] FUTEX_WAK... |
1022 |
|
ec92d0829 futex priority ba... |
1023 |
plist_for_each_entry_safe(this, next, head, list) { |
4732efbeb [PATCH] FUTEX_WAK... |
1024 1025 1026 1027 1028 1029 1030 1031 |
if (match_futex (&this->key, &key1)) { wake_futex(this); if (++ret >= nr_wake) break; } } if (op_ret > 0) { |
e2970f2fb [PATCH] pi-futex:... |
1032 |
head = &hb2->chain; |
4732efbeb [PATCH] FUTEX_WAK... |
1033 1034 |
op_ret = 0; |
ec92d0829 futex priority ba... |
1035 |
plist_for_each_entry_safe(this, next, head, list) { |
4732efbeb [PATCH] FUTEX_WAK... |
1036 1037 1038 1039 1040 1041 1042 1043 |
if (match_futex (&this->key, &key2)) { wake_futex(this); if (++op_ret >= nr_wake2) break; } } ret += op_ret; } |
5eb3dc62f futex: add double... |
1044 |
double_unlock_hb(hb1, hb2); |
42d35d48c futex: make futex... |
1045 |
out_put_keys: |
ae791a2d2 futex: Cleanup st... |
1046 |
put_futex_key(&key2); |
42d35d48c futex: make futex... |
1047 |
out_put_key1: |
ae791a2d2 futex: Cleanup st... |
1048 |
put_futex_key(&key1); |
42d35d48c futex: make futex... |
1049 |
out: |
4732efbeb [PATCH] FUTEX_WAK... |
1050 1051 |
return ret; } |
9121e4783 futex: distangle ... |
1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 |
/** * 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); plist_add(&q->list, &hb2->chain); q->lock_ptr = &hb2->lock; |
9121e4783 futex: distangle ... |
1072 1073 1074 1075 |
} get_futex_key_refs(key2); q->key = *key2; } |
52400ba94 futex: add requeu... |
1076 1077 |
/** * requeue_pi_wake_futex() - Wake a task that acquired the lock during requeue |
d96ee56ce futex: Make funct... |
1078 1079 1080 |
* @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... |
1081 1082 1083 1084 1085 |
* * 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... |
1086 1087 1088 |
* 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... |
1089 1090 |
*/ static inline |
beda2c7ea futex: Update fut... |
1091 1092 |
void requeue_pi_wake_futex(struct futex_q *q, union futex_key *key, struct futex_hash_bucket *hb) |
52400ba94 futex: add requeu... |
1093 |
{ |
52400ba94 futex: add requeu... |
1094 1095 |
get_futex_key_refs(key); q->key = *key; |
2e12978a9 futex,plist: Pass... |
1096 |
__unqueue_futex(q); |
52400ba94 futex: add requeu... |
1097 1098 1099 |
WARN_ON(!q->rt_waiter); q->rt_waiter = NULL; |
beda2c7ea futex: Update fut... |
1100 |
q->lock_ptr = &hb->lock; |
beda2c7ea futex: Update fut... |
1101 |
|
f1a11e057 futex: remove the... |
1102 |
wake_up_state(q->task, TASK_NORMAL); |
52400ba94 futex: add requeu... |
1103 1104 1105 1106 |
} /** * futex_proxy_trylock_atomic() - Attempt an atomic lock for the top waiter |
bab5bc9e8 futex: fixup unlo... |
1107 1108 1109 1110 1111 1112 1113 |
* @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... |
1114 1115 |
* * Try and get the lock on behalf of the top waiter if we can do it atomically. |
bab5bc9e8 futex: fixup unlo... |
1116 1117 1118 |
* 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... |
1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 |
* * Returns: * 0 - failed to acquire the lock atomicly * 1 - acquired the lock * <0 - error */ 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... |
1129 |
struct futex_pi_state **ps, int set_waiters) |
52400ba94 futex: add requeu... |
1130 |
{ |
bab5bc9e8 futex: fixup unlo... |
1131 |
struct futex_q *top_waiter = NULL; |
52400ba94 futex: add requeu... |
1132 1133 1134 1135 1136 |
u32 curval; int ret; if (get_futex_value_locked(&curval, pifutex)) return -EFAULT; |
bab5bc9e8 futex: fixup unlo... |
1137 1138 1139 1140 1141 1142 1143 1144 |
/* * 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... |
1145 1146 1147 1148 1149 |
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... |
1150 1151 1152 |
/* Ensure we requeue to the expected futex. */ if (!match_futex(top_waiter->requeue_pi_key, key2)) return -EINVAL; |
52400ba94 futex: add requeu... |
1153 |
/* |
bab5bc9e8 futex: fixup unlo... |
1154 1155 1156 |
* 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... |
1157 |
*/ |
bab5bc9e8 futex: fixup unlo... |
1158 1159 |
ret = futex_lock_pi_atomic(pifutex, hb2, key2, ps, top_waiter->task, set_waiters); |
52400ba94 futex: add requeu... |
1160 |
if (ret == 1) |
beda2c7ea futex: Update fut... |
1161 |
requeue_pi_wake_futex(top_waiter, key2, hb2); |
52400ba94 futex: add requeu... |
1162 1163 1164 1165 1166 1167 |
return ret; } /** * futex_requeue() - Requeue waiters from uaddr1 to uaddr2 |
fb62db2ba futex: Fix kernel... |
1168 |
* @uaddr1: source futex user address |
b41277dc7 futex: Replace fs... |
1169 |
* @flags: futex flags (FLAGS_SHARED, etc.) |
fb62db2ba futex: Fix kernel... |
1170 1171 1172 1173 1174 |
* @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... |
1175 |
* pi futex (pi to pi requeue is not supported) |
52400ba94 futex: add requeu... |
1176 1177 1178 1179 1180 1181 1182 |
* * Requeue waiters on uaddr1 to uaddr2. In the requeue_pi case, try to acquire * uaddr2 atomically on behalf of the top waiter. * * Returns: * >=0 - on success, the number of tasks requeued or woken * <0 - on error |
1da177e4c Linux-2.6.12-rc2 |
1183 |
*/ |
b41277dc7 futex: Replace fs... |
1184 1185 1186 |
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 |
1187 |
{ |
38d47c1b7 futex: rely on ge... |
1188 |
union futex_key key1 = FUTEX_KEY_INIT, key2 = FUTEX_KEY_INIT; |
52400ba94 futex: add requeu... |
1189 1190 |
int drop_count = 0, task_count = 0, ret; struct futex_pi_state *pi_state = NULL; |
e2970f2fb [PATCH] pi-futex:... |
1191 |
struct futex_hash_bucket *hb1, *hb2; |
ec92d0829 futex priority ba... |
1192 |
struct plist_head *head1; |
1da177e4c Linux-2.6.12-rc2 |
1193 |
struct futex_q *this, *next; |
52400ba94 futex: add requeu... |
1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 |
u32 curval2; if (requeue_pi) { /* * 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 |
1216 |
|
42d35d48c futex: make futex... |
1217 |
retry: |
52400ba94 futex: add requeu... |
1218 1219 1220 1221 1222 1223 1224 1225 |
if (pi_state != NULL) { /* * We will have to lookup the pi_state again, so free this one * to keep the accounting correct. */ free_pi_state(pi_state); pi_state = NULL; } |
9ea71503a futex: Fix regres... |
1226 |
ret = get_futex_key(uaddr1, flags & FLAGS_SHARED, &key1, VERIFY_READ); |
1da177e4c Linux-2.6.12-rc2 |
1227 1228 |
if (unlikely(ret != 0)) goto out; |
9ea71503a futex: Fix regres... |
1229 1230 |
ret = get_futex_key(uaddr2, flags & FLAGS_SHARED, &key2, requeue_pi ? VERIFY_WRITE : VERIFY_READ); |
1da177e4c Linux-2.6.12-rc2 |
1231 |
if (unlikely(ret != 0)) |
42d35d48c futex: make futex... |
1232 |
goto out_put_key1; |
1da177e4c Linux-2.6.12-rc2 |
1233 |
|
e2970f2fb [PATCH] pi-futex:... |
1234 1235 |
hb1 = hash_futex(&key1); hb2 = hash_futex(&key2); |
1da177e4c Linux-2.6.12-rc2 |
1236 |
|
e4dc5b7a3 futex: clean up f... |
1237 |
retry_private: |
8b8f319fc [PATCH] lockdep: ... |
1238 |
double_lock_hb(hb1, hb2); |
1da177e4c Linux-2.6.12-rc2 |
1239 |
|
e2970f2fb [PATCH] pi-futex:... |
1240 1241 |
if (likely(cmpval != NULL)) { u32 curval; |
1da177e4c Linux-2.6.12-rc2 |
1242 |
|
e2970f2fb [PATCH] pi-futex:... |
1243 |
ret = get_futex_value_locked(&curval, uaddr1); |
1da177e4c Linux-2.6.12-rc2 |
1244 1245 |
if (unlikely(ret)) { |
5eb3dc62f futex: add double... |
1246 |
double_unlock_hb(hb1, hb2); |
1da177e4c Linux-2.6.12-rc2 |
1247 |
|
e2970f2fb [PATCH] pi-futex:... |
1248 |
ret = get_user(curval, uaddr1); |
e4dc5b7a3 futex: clean up f... |
1249 1250 |
if (ret) goto out_put_keys; |
1da177e4c Linux-2.6.12-rc2 |
1251 |
|
b41277dc7 futex: Replace fs... |
1252 |
if (!(flags & FLAGS_SHARED)) |
e4dc5b7a3 futex: clean up f... |
1253 |
goto retry_private; |
1da177e4c Linux-2.6.12-rc2 |
1254 |
|
ae791a2d2 futex: Cleanup st... |
1255 1256 |
put_futex_key(&key2); put_futex_key(&key1); |
e4dc5b7a3 futex: clean up f... |
1257 |
goto retry; |
1da177e4c Linux-2.6.12-rc2 |
1258 |
} |
e2970f2fb [PATCH] pi-futex:... |
1259 |
if (curval != *cmpval) { |
1da177e4c Linux-2.6.12-rc2 |
1260 1261 1262 1263 |
ret = -EAGAIN; goto out_unlock; } } |
52400ba94 futex: add requeu... |
1264 |
if (requeue_pi && (task_count - nr_wake < nr_requeue)) { |
bab5bc9e8 futex: fixup unlo... |
1265 1266 1267 1268 1269 1270 |
/* * 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... |
1271 |
ret = futex_proxy_trylock_atomic(uaddr2, hb1, hb2, &key1, |
bab5bc9e8 futex: fixup unlo... |
1272 |
&key2, &pi_state, nr_requeue); |
52400ba94 futex: add requeu... |
1273 1274 1275 1276 1277 1278 1279 1280 1281 |
/* * 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 * reference to it. */ if (ret == 1) { WARN_ON(pi_state); |
89061d3d5 futex: Move drop_... |
1282 |
drop_count++; |
52400ba94 futex: add requeu... |
1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 |
task_count++; ret = get_futex_value_locked(&curval2, uaddr2); if (!ret) ret = lookup_pi_state(curval2, hb2, &key2, &pi_state); } switch (ret) { case 0: break; case -EFAULT: double_unlock_hb(hb1, hb2); |
ae791a2d2 futex: Cleanup st... |
1295 1296 |
put_futex_key(&key2); put_futex_key(&key1); |
d0725992c futex: Fix the wr... |
1297 |
ret = fault_in_user_writeable(uaddr2); |
52400ba94 futex: add requeu... |
1298 1299 1300 1301 1302 1303 |
if (!ret) goto retry; goto out; case -EAGAIN: /* The owner was exiting, try again. */ double_unlock_hb(hb1, hb2); |
ae791a2d2 futex: Cleanup st... |
1304 1305 |
put_futex_key(&key2); put_futex_key(&key1); |
52400ba94 futex: add requeu... |
1306 1307 1308 1309 1310 1311 |
cond_resched(); goto retry; default: goto out_unlock; } } |
e2970f2fb [PATCH] pi-futex:... |
1312 |
head1 = &hb1->chain; |
ec92d0829 futex priority ba... |
1313 |
plist_for_each_entry_safe(this, next, head1, list) { |
52400ba94 futex: add requeu... |
1314 1315 1316 1317 |
if (task_count - nr_wake >= nr_requeue) break; if (!match_futex(&this->key, &key1)) |
1da177e4c Linux-2.6.12-rc2 |
1318 |
continue; |
52400ba94 futex: add requeu... |
1319 |
|
392741e0a futex: Fix handli... |
1320 1321 1322 1323 1324 1325 1326 1327 1328 |
/* * FUTEX_WAIT_REQEUE_PI and FUTEX_CMP_REQUEUE_PI should always * be paired with each other and no other futex ops. */ if ((requeue_pi && !this->rt_waiter) || (!requeue_pi && this->rt_waiter)) { ret = -EINVAL; break; } |
52400ba94 futex: add requeu... |
1329 1330 1331 1332 1333 1334 1335 |
/* * 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) { |
1da177e4c Linux-2.6.12-rc2 |
1336 |
wake_futex(this); |
52400ba94 futex: add requeu... |
1337 1338 |
continue; } |
1da177e4c Linux-2.6.12-rc2 |
1339 |
|
84bc4af59 futex: Detect mis... |
1340 1341 1342 1343 1344 |
/* 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... |
1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 |
/* * 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) { /* Prepare the waiter to take the rt_mutex. */ atomic_inc(&pi_state->refcount); this->pi_state = pi_state; ret = rt_mutex_start_proxy_lock(&pi_state->pi_mutex, this->rt_waiter, this->task, 1); if (ret == 1) { /* We got the lock. */ |
beda2c7ea futex: Update fut... |
1358 |
requeue_pi_wake_futex(this, &key2, hb2); |
89061d3d5 futex: Move drop_... |
1359 |
drop_count++; |
52400ba94 futex: add requeu... |
1360 1361 1362 1363 1364 1365 1366 |
continue; } else if (ret) { /* -EDEADLK */ this->pi_state = NULL; free_pi_state(pi_state); goto out_unlock; } |
1da177e4c Linux-2.6.12-rc2 |
1367 |
} |
52400ba94 futex: add requeu... |
1368 1369 |
requeue_futex(this, hb1, hb2, &key2); drop_count++; |
1da177e4c Linux-2.6.12-rc2 |
1370 1371 1372 |
} out_unlock: |
5eb3dc62f futex: add double... |
1373 |
double_unlock_hb(hb1, hb2); |
1da177e4c Linux-2.6.12-rc2 |
1374 |
|
cd84a42f3 futex: comment re... |
1375 1376 1377 1378 1379 1380 |
/* * 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 |
1381 |
while (--drop_count >= 0) |
9adef58b1 futex: get_futex_... |
1382 |
drop_futex_key_refs(&key1); |
1da177e4c Linux-2.6.12-rc2 |
1383 |
|
42d35d48c futex: make futex... |
1384 |
out_put_keys: |
ae791a2d2 futex: Cleanup st... |
1385 |
put_futex_key(&key2); |
42d35d48c futex: make futex... |
1386 |
out_put_key1: |
ae791a2d2 futex: Cleanup st... |
1387 |
put_futex_key(&key1); |
42d35d48c futex: make futex... |
1388 |
out: |
52400ba94 futex: add requeu... |
1389 1390 1391 |
if (pi_state != NULL) free_pi_state(pi_state); return ret ? ret : task_count; |
1da177e4c Linux-2.6.12-rc2 |
1392 1393 1394 |
} /* The key must be already stored in q->key. */ |
82af7aca5 Removal of FUTEX_FD |
1395 |
static inline struct futex_hash_bucket *queue_lock(struct futex_q *q) |
15e408cd6 futex: Add lock c... |
1396 |
__acquires(&hb->lock) |
1da177e4c Linux-2.6.12-rc2 |
1397 |
{ |
e2970f2fb [PATCH] pi-futex:... |
1398 |
struct futex_hash_bucket *hb; |
1da177e4c Linux-2.6.12-rc2 |
1399 |
|
e2970f2fb [PATCH] pi-futex:... |
1400 1401 |
hb = hash_futex(&q->key); q->lock_ptr = &hb->lock; |
1da177e4c Linux-2.6.12-rc2 |
1402 |
|
e2970f2fb [PATCH] pi-futex:... |
1403 1404 |
spin_lock(&hb->lock); return hb; |
1da177e4c Linux-2.6.12-rc2 |
1405 |
} |
d40d65c8d futex: Correct qu... |
1406 1407 |
static inline void queue_unlock(struct futex_q *q, struct futex_hash_bucket *hb) |
15e408cd6 futex: Add lock c... |
1408 |
__releases(&hb->lock) |
d40d65c8d futex: Correct qu... |
1409 1410 |
{ spin_unlock(&hb->lock); |
d40d65c8d futex: Correct qu... |
1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 |
} /** * 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). */ |
82af7aca5 Removal of FUTEX_FD |
1425 |
static inline void queue_me(struct futex_q *q, struct futex_hash_bucket *hb) |
15e408cd6 futex: Add lock c... |
1426 |
__releases(&hb->lock) |
1da177e4c Linux-2.6.12-rc2 |
1427 |
{ |
ec92d0829 futex priority ba... |
1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 |
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... |
1441 |
plist_add(&q->list, &hb->chain); |
c87e2837b [PATCH] pi-futex:... |
1442 |
q->task = current; |
e2970f2fb [PATCH] pi-futex:... |
1443 |
spin_unlock(&hb->lock); |
1da177e4c Linux-2.6.12-rc2 |
1444 |
} |
d40d65c8d futex: Correct qu... |
1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 |
/** * 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(). * * Returns: * 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 |
1455 |
*/ |
1da177e4c Linux-2.6.12-rc2 |
1456 1457 |
static int unqueue_me(struct futex_q *q) { |
1da177e4c Linux-2.6.12-rc2 |
1458 |
spinlock_t *lock_ptr; |
e2970f2fb [PATCH] pi-futex:... |
1459 |
int ret = 0; |
1da177e4c Linux-2.6.12-rc2 |
1460 1461 |
/* In the common case we don't take the spinlock, which is nice. */ |
42d35d48c futex: make futex... |
1462 |
retry: |
1da177e4c Linux-2.6.12-rc2 |
1463 |
lock_ptr = q->lock_ptr; |
e91467ecd [PATCH] bug in fu... |
1464 |
barrier(); |
c80544dc0 sparse pointer us... |
1465 |
if (lock_ptr != NULL) { |
1da177e4c Linux-2.6.12-rc2 |
1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 |
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... |
1484 |
__unqueue_futex(q); |
c87e2837b [PATCH] pi-futex:... |
1485 1486 |
BUG_ON(q->pi_state); |
1da177e4c Linux-2.6.12-rc2 |
1487 1488 1489 |
spin_unlock(lock_ptr); ret = 1; } |
9adef58b1 futex: get_futex_... |
1490 |
drop_futex_key_refs(&q->key); |
1da177e4c Linux-2.6.12-rc2 |
1491 1492 |
return ret; } |
c87e2837b [PATCH] pi-futex:... |
1493 1494 |
/* * PI futexes can not be requeued and must remove themself from the |
d0aa7a70b futex_requeue_pi ... |
1495 1496 |
* hash bucket. The hash bucket lock (i.e. lock_ptr) is held on entry * and dropped here. |
c87e2837b [PATCH] pi-futex:... |
1497 |
*/ |
d0aa7a70b futex_requeue_pi ... |
1498 |
static void unqueue_me_pi(struct futex_q *q) |
15e408cd6 futex: Add lock c... |
1499 |
__releases(q->lock_ptr) |
c87e2837b [PATCH] pi-futex:... |
1500 |
{ |
2e12978a9 futex,plist: Pass... |
1501 |
__unqueue_futex(q); |
c87e2837b [PATCH] pi-futex:... |
1502 1503 1504 1505 |
BUG_ON(!q->pi_state); free_pi_state(q->pi_state); q->pi_state = NULL; |
d0aa7a70b futex_requeue_pi ... |
1506 |
spin_unlock(q->lock_ptr); |
c87e2837b [PATCH] pi-futex:... |
1507 |
} |
d0aa7a70b futex_requeue_pi ... |
1508 |
/* |
cdf71a10c futex: Prevent st... |
1509 |
* Fixup the pi_state owner with the new owner. |
d0aa7a70b futex_requeue_pi ... |
1510 |
* |
778e9a9c3 pi-futex: fix exi... |
1511 1512 |
* Must be called with hash bucket lock held and mm->sem held for non * private futexes. |
d0aa7a70b futex_requeue_pi ... |
1513 |
*/ |
778e9a9c3 pi-futex: fix exi... |
1514 |
static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q, |
ae791a2d2 futex: Cleanup st... |
1515 |
struct task_struct *newowner) |
d0aa7a70b futex_requeue_pi ... |
1516 |
{ |
cdf71a10c futex: Prevent st... |
1517 |
u32 newtid = task_pid_vnr(newowner) | FUTEX_WAITERS; |
d0aa7a70b futex_requeue_pi ... |
1518 |
struct futex_pi_state *pi_state = q->pi_state; |
1b7558e45 futexes: fix faul... |
1519 |
struct task_struct *oldowner = pi_state->owner; |
7cfdaf38d futex: uninitiali... |
1520 |
u32 uval, uninitialized_var(curval), newval; |
e4dc5b7a3 futex: clean up f... |
1521 |
int ret; |
d0aa7a70b futex_requeue_pi ... |
1522 1523 |
/* Owner died? */ |
1b7558e45 futexes: fix faul... |
1524 1525 1526 1527 1528 |
if (!pi_state->owner) newtid |= FUTEX_OWNER_DIED; /* * We are here either because we stole the rtmutex from the |
8161239a8 rtmutex: Simplify... |
1529 1530 1531 1532 |
* previous highest priority waiter or we are the highest priority * waiter but failed to get the rtmutex the first time. * 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... |
1533 |
* |
b2d0994b1 futex: update fut... |
1534 1535 1536 |
* 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... |
1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 |
* * 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 hash bucket lock to * handle the fault. This might be observed in the PID check * in lookup_pi_state. */ retry: if (get_futex_value_locked(&uval, uaddr)) goto handle_fault; while (1) { newval = (uval & FUTEX_OWNER_DIED) | newtid; |
37a9d912b futex: Sanitize c... |
1550 |
if (cmpxchg_futex_value_locked(&curval, uaddr, uval, newval)) |
1b7558e45 futexes: fix faul... |
1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 |
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 ... |
1561 |
if (pi_state->owner != NULL) { |
1d6154825 sched: Convert pi... |
1562 |
raw_spin_lock_irq(&pi_state->owner->pi_lock); |
d0aa7a70b futex_requeue_pi ... |
1563 1564 |
WARN_ON(list_empty(&pi_state->list)); list_del_init(&pi_state->list); |
1d6154825 sched: Convert pi... |
1565 |
raw_spin_unlock_irq(&pi_state->owner->pi_lock); |
1b7558e45 futexes: fix faul... |
1566 |
} |
d0aa7a70b futex_requeue_pi ... |
1567 |
|
cdf71a10c futex: Prevent st... |
1568 |
pi_state->owner = newowner; |
d0aa7a70b futex_requeue_pi ... |
1569 |
|
1d6154825 sched: Convert pi... |
1570 |
raw_spin_lock_irq(&newowner->pi_lock); |
d0aa7a70b futex_requeue_pi ... |
1571 |
WARN_ON(!list_empty(&pi_state->list)); |
cdf71a10c futex: Prevent st... |
1572 |
list_add(&pi_state->list, &newowner->pi_state_list); |
1d6154825 sched: Convert pi... |
1573 |
raw_spin_unlock_irq(&newowner->pi_lock); |
1b7558e45 futexes: fix faul... |
1574 |
return 0; |
d0aa7a70b futex_requeue_pi ... |
1575 |
|
d0aa7a70b futex_requeue_pi ... |
1576 |
/* |
1b7558e45 futexes: fix faul... |
1577 |
* To handle the page fault we need to drop the hash bucket |
8161239a8 rtmutex: Simplify... |
1578 1579 |
* lock here. That gives the other task (either the highest priority * waiter itself or the task which stole the rtmutex) the |
1b7558e45 futexes: fix faul... |
1580 1581 1582 1583 1584 |
* 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 hash bucket lock and before trying to * do another fixup. When the fixup has been done already we * simply return. |
d0aa7a70b futex_requeue_pi ... |
1585 |
*/ |
1b7558e45 futexes: fix faul... |
1586 1587 |
handle_fault: spin_unlock(q->lock_ptr); |
778e9a9c3 pi-futex: fix exi... |
1588 |
|
d0725992c futex: Fix the wr... |
1589 |
ret = fault_in_user_writeable(uaddr); |
778e9a9c3 pi-futex: fix exi... |
1590 |
|
1b7558e45 futexes: fix faul... |
1591 |
spin_lock(q->lock_ptr); |
778e9a9c3 pi-futex: fix exi... |
1592 |
|
1b7558e45 futexes: fix faul... |
1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 |
/* * Check if someone else fixed it for us: */ if (pi_state->owner != oldowner) return 0; if (ret) return ret; goto retry; |
d0aa7a70b futex_requeue_pi ... |
1603 |
} |
72c1bbf30 futex: restartabl... |
1604 |
static long futex_wait_restart(struct restart_block *restart); |
36cf3b5c3 FUTEX: Tidy up th... |
1605 |
|
ca5f9524d futex: separate f... |
1606 |
/** |
dd9739980 futex: split out ... |
1607 1608 |
* fixup_owner() - Post lock pi_state and corner case management * @uaddr: user address of the futex |
dd9739980 futex: split out ... |
1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 |
* @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. * * Returns: * 1 - success, lock taken * 0 - success, lock not taken * <0 - on error (-EFAULT) */ |
ae791a2d2 futex: Cleanup st... |
1621 |
static int fixup_owner(u32 __user *uaddr, struct futex_q *q, int locked) |
dd9739980 futex: split out ... |
1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 |
{ struct task_struct *owner; 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: */ if (q->pi_state->owner != current) |
ae791a2d2 futex: Cleanup st... |
1632 |
ret = fixup_pi_state_owner(uaddr, q, current); |
dd9739980 futex: split out ... |
1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 |
goto out; } /* * Catch the rare case, where the lock was released when we were on the * way back before we locked the hash bucket. */ if (q->pi_state->owner == current) { /* * Try to get the rt_mutex now. This might fail as some other * task acquired the rt_mutex after we removed ourself from the * rt_mutex waiters list. */ if (rt_mutex_trylock(&q->pi_state->pi_mutex)) { locked = 1; goto out; } /* * pi_state is incorrect, some other task did a lock steal and * we returned due to timeout or signal without taking the |
8161239a8 rtmutex: Simplify... |
1654 |
* rt_mutex. Too late. |
dd9739980 futex: split out ... |
1655 |
*/ |
8161239a8 rtmutex: Simplify... |
1656 |
raw_spin_lock(&q->pi_state->pi_mutex.wait_lock); |
dd9739980 futex: split out ... |
1657 |
owner = rt_mutex_owner(&q->pi_state->pi_mutex); |
8161239a8 rtmutex: Simplify... |
1658 1659 1660 |
if (!owner) owner = rt_mutex_next_owner(&q->pi_state->pi_mutex); raw_spin_unlock(&q->pi_state->pi_mutex.wait_lock); |
ae791a2d2 futex: Cleanup st... |
1661 |
ret = fixup_pi_state_owner(uaddr, q, owner); |
dd9739980 futex: split out ... |
1662 1663 1664 1665 1666 |
goto out; } /* * Paranoia check. If we did not take the lock, then we should not be |
8161239a8 rtmutex: Simplify... |
1667 |
* the owner of the rt_mutex. |
dd9739980 futex: split out ... |
1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 |
*/ if (rt_mutex_owner(&q->pi_state->pi_mutex) == current) printk(KERN_ERR "fixup_owner: ret = %d pi-mutex: %p " "pi-state %p ", ret, q->pi_state->pi_mutex.owner, q->pi_state->owner); out: return ret ? ret : locked; } /** |
ca5f9524d futex: separate f... |
1681 1682 1683 1684 |
* 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... |
1685 1686 |
*/ static void futex_wait_queue_me(struct futex_hash_bucket *hb, struct futex_q *q, |
f1a11e057 futex: remove the... |
1687 |
struct hrtimer_sleeper *timeout) |
ca5f9524d futex: separate f... |
1688 |
{ |
9beba3c54 futex: Add memory... |
1689 1690 1691 1692 1693 1694 |
/* * The task state is guaranteed to be set before another task can * wake it. set_current_state() is implemented using set_mb() and * queue_me() calls spin_unlock() upon completion, both serializing * access to the hash list and forcing another memory barrier. */ |
f1a11e057 futex: remove the... |
1695 |
set_current_state(TASK_INTERRUPTIBLE); |
0729e1961 futex: Fix wakeup... |
1696 |
queue_me(q, hb); |
ca5f9524d futex: separate f... |
1697 1698 1699 1700 1701 1702 1703 1704 1705 |
/* Arm the timer */ if (timeout) { hrtimer_start_expires(&timeout->timer, HRTIMER_MODE_ABS); if (!hrtimer_active(&timeout->timer)) timeout->task = NULL; } /* |
0729e1961 futex: Fix wakeup... |
1706 1707 |
* 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... |
1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 |
*/ 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) schedule(); } __set_current_state(TASK_RUNNING); } |
f801073f8 futex: split out ... |
1720 1721 1722 1723 |
/** * futex_wait_setup() - Prepare to wait on a futex * @uaddr: the futex userspace address * @val: the expected value |
b41277dc7 futex: Replace fs... |
1724 |
* @flags: futex flags (FLAGS_SHARED, etc.) |
f801073f8 futex: split out ... |
1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 |
* @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. * * Returns: * 0 - uaddr contains val and hb has been locked |
ca4a04cf3 futex: Fix spelli... |
1735 |
* <1 - -EFAULT or -EWOULDBLOCK (uaddr does not contain val) and hb is unlocked |
f801073f8 futex: split out ... |
1736 |
*/ |
b41277dc7 futex: Replace fs... |
1737 |
static int futex_wait_setup(u32 __user *uaddr, u32 val, unsigned int flags, |
f801073f8 futex: split out ... |
1738 |
struct futex_q *q, struct futex_hash_bucket **hb) |
1da177e4c Linux-2.6.12-rc2 |
1739 |
{ |
e2970f2fb [PATCH] pi-futex:... |
1740 1741 |
u32 uval; int ret; |
1da177e4c Linux-2.6.12-rc2 |
1742 |
|
1da177e4c Linux-2.6.12-rc2 |
1743 |
/* |
b2d0994b1 futex: update fut... |
1744 |
* Access the page AFTER the hash-bucket is locked. |
1da177e4c Linux-2.6.12-rc2 |
1745 1746 1747 1748 1749 1750 1751 |
* 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... |
1752 1753 |
* 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 |
1754 1755 |
* cond(var) false, which would violate the guarantee. * |
8fe8f545c futex: Update fut... |
1756 1757 1758 1759 |
* 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 |
1760 |
*/ |
f801073f8 futex: split out ... |
1761 |
retry: |
9ea71503a futex: Fix regres... |
1762 |
ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &q->key, VERIFY_READ); |
f801073f8 futex: split out ... |
1763 |
if (unlikely(ret != 0)) |
a5a2a0c7f futex: fix futex_... |
1764 |
return ret; |
f801073f8 futex: split out ... |
1765 1766 1767 |
retry_private: *hb = queue_lock(q); |
e2970f2fb [PATCH] pi-futex:... |
1768 |
ret = get_futex_value_locked(&uval, uaddr); |
1da177e4c Linux-2.6.12-rc2 |
1769 |
|
f801073f8 futex: split out ... |
1770 1771 |
if (ret) { queue_unlock(q, *hb); |
1da177e4c Linux-2.6.12-rc2 |
1772 |
|
e2970f2fb [PATCH] pi-futex:... |
1773 |
ret = get_user(uval, uaddr); |
e4dc5b7a3 futex: clean up f... |
1774 |
if (ret) |
f801073f8 futex: split out ... |
1775 |
goto out; |
1da177e4c Linux-2.6.12-rc2 |
1776 |
|
b41277dc7 futex: Replace fs... |
1777 |
if (!(flags & FLAGS_SHARED)) |
e4dc5b7a3 futex: clean up f... |
1778 |
goto retry_private; |
ae791a2d2 futex: Cleanup st... |
1779 |
put_futex_key(&q->key); |
e4dc5b7a3 futex: clean up f... |
1780 |
goto retry; |
1da177e4c Linux-2.6.12-rc2 |
1781 |
} |
ca5f9524d futex: separate f... |
1782 |
|
f801073f8 futex: split out ... |
1783 1784 1785 |
if (uval != val) { queue_unlock(q, *hb); ret = -EWOULDBLOCK; |
2fff78c78 futex: fix refere... |
1786 |
} |
1da177e4c Linux-2.6.12-rc2 |
1787 |
|
f801073f8 futex: split out ... |
1788 1789 |
out: if (ret) |
ae791a2d2 futex: Cleanup st... |
1790 |
put_futex_key(&q->key); |
f801073f8 futex: split out ... |
1791 1792 |
return ret; } |
b41277dc7 futex: Replace fs... |
1793 1794 |
static int futex_wait(u32 __user *uaddr, unsigned int flags, u32 val, ktime_t *abs_time, u32 bitset) |
f801073f8 futex: split out ... |
1795 1796 |
{ struct hrtimer_sleeper timeout, *to = NULL; |
f801073f8 futex: split out ... |
1797 1798 |
struct restart_block *restart; struct futex_hash_bucket *hb; |
5bdb05f91 futex: Add futex_... |
1799 |
struct futex_q q = futex_q_init; |
f801073f8 futex: split out ... |
1800 1801 1802 1803 |
int ret; if (!bitset) return -EINVAL; |
f801073f8 futex: split out ... |
1804 1805 1806 1807 |
q.bitset = bitset; if (abs_time) { to = &timeout; |
b41277dc7 futex: Replace fs... |
1808 1809 1810 |
hrtimer_init_on_stack(&to->timer, (flags & FLAGS_CLOCKRT) ? CLOCK_REALTIME : CLOCK_MONOTONIC, HRTIMER_MODE_ABS); |
f801073f8 futex: split out ... |
1811 1812 1813 1814 |
hrtimer_init_sleeper(to, current); hrtimer_set_expires_range_ns(&to->timer, *abs_time, current->timer_slack_ns); } |
d58e6576b futex: Handle spu... |
1815 |
retry: |
7ada876a8 futex: Fix errors... |
1816 1817 1818 1819 |
/* * Prepare to wait on uaddr. On success, holds hb lock and increments * q.key refs. */ |
b41277dc7 futex: Replace fs... |
1820 |
ret = futex_wait_setup(uaddr, val, flags, &q, &hb); |
f801073f8 futex: split out ... |
1821 1822 |
if (ret) goto out; |
ca5f9524d futex: separate f... |
1823 |
/* queue_me and wait for wakeup, timeout, or a signal. */ |
f1a11e057 futex: remove the... |
1824 |
futex_wait_queue_me(hb, &q, to); |
1da177e4c Linux-2.6.12-rc2 |
1825 1826 |
/* If we were woken (and unqueued), we succeeded, whatever. */ |
2fff78c78 futex: fix refere... |
1827 |
ret = 0; |
7ada876a8 futex: Fix errors... |
1828 |
/* unqueue_me() drops q.key ref */ |
1da177e4c Linux-2.6.12-rc2 |
1829 |
if (!unqueue_me(&q)) |
7ada876a8 futex: Fix errors... |
1830 |
goto out; |
2fff78c78 futex: fix refere... |
1831 |
ret = -ETIMEDOUT; |
ca5f9524d futex: separate f... |
1832 |
if (to && !to->task) |
7ada876a8 futex: Fix errors... |
1833 |
goto out; |
72c1bbf30 futex: restartabl... |
1834 |
|
e2970f2fb [PATCH] pi-futex:... |
1835 |
/* |
d58e6576b futex: Handle spu... |
1836 1837 |
* We expect signal_pending(current), but we might be the * victim of a spurious wakeup as well. |
e2970f2fb [PATCH] pi-futex:... |
1838 |
*/ |
7ada876a8 futex: Fix errors... |
1839 |
if (!signal_pending(current)) |
d58e6576b futex: Handle spu... |
1840 |
goto retry; |
d58e6576b futex: Handle spu... |
1841 |
|
2fff78c78 futex: fix refere... |
1842 |
ret = -ERESTARTSYS; |
c19384b5b Make futex_wait()... |
1843 |
if (!abs_time) |
7ada876a8 futex: Fix errors... |
1844 |
goto out; |
1da177e4c Linux-2.6.12-rc2 |
1845 |
|
2fff78c78 futex: fix refere... |
1846 1847 |
restart = ¤t_thread_info()->restart_block; restart->fn = futex_wait_restart; |
a3c74c525 futex: Mark resta... |
1848 |
restart->futex.uaddr = uaddr; |
2fff78c78 futex: fix refere... |
1849 1850 1851 |
restart->futex.val = val; restart->futex.time = abs_time->tv64; restart->futex.bitset = bitset; |
0cd9c6494 futex: Set FLAGS_... |
1852 |
restart->futex.flags = flags | FLAGS_HAS_TIMEOUT; |
42d35d48c futex: make futex... |
1853 |
|
2fff78c78 futex: fix refere... |
1854 |
ret = -ERESTART_RESTARTBLOCK; |
42d35d48c futex: make futex... |
1855 |
out: |
ca5f9524d futex: separate f... |
1856 1857 1858 1859 |
if (to) { hrtimer_cancel(&to->timer); destroy_hrtimer_on_stack(&to->timer); } |
c87e2837b [PATCH] pi-futex:... |
1860 1861 |
return ret; } |
72c1bbf30 futex: restartabl... |
1862 1863 1864 |
static long futex_wait_restart(struct restart_block *restart) { |
a3c74c525 futex: Mark resta... |
1865 |
u32 __user *uaddr = restart->futex.uaddr; |
a72188d8a futex: add FUTEX_... |
1866 |
ktime_t t, *tp = NULL; |
72c1bbf30 futex: restartabl... |
1867 |
|
a72188d8a futex: add FUTEX_... |
1868 1869 1870 1871 |
if (restart->futex.flags & FLAGS_HAS_TIMEOUT) { t.tv64 = restart->futex.time; tp = &t; } |
72c1bbf30 futex: restartabl... |
1872 |
restart->fn = do_no_restart_syscall; |
b41277dc7 futex: Replace fs... |
1873 1874 1875 |
return (long)futex_wait(uaddr, restart->futex.flags, restart->futex.val, tp, restart->futex.bitset); |
72c1bbf30 futex: restartabl... |
1876 |
} |
c87e2837b [PATCH] pi-futex:... |
1877 1878 1879 1880 1881 1882 |
/* * Userspace tried a 0 -> TID atomic transition of the futex value * and failed. The kernel side here does the whole locking operation: * if there are waiters then it will block, it does PI, etc. (Due to * races the kernel might see a 0 value of the futex too.) */ |
b41277dc7 futex: Replace fs... |
1883 1884 |
static int futex_lock_pi(u32 __user *uaddr, unsigned int flags, int detect, ktime_t *time, int trylock) |
c87e2837b [PATCH] pi-futex:... |
1885 |
{ |
c5780e976 [PATCH] Use the c... |
1886 |
struct hrtimer_sleeper timeout, *to = NULL; |
c87e2837b [PATCH] pi-futex:... |
1887 |
struct futex_hash_bucket *hb; |
5bdb05f91 futex: Add futex_... |
1888 |
struct futex_q q = futex_q_init; |
dd9739980 futex: split out ... |
1889 |
int res, ret; |
c87e2837b [PATCH] pi-futex:... |
1890 1891 1892 |
if (refill_pi_state_cache()) return -ENOMEM; |
c19384b5b Make futex_wait()... |
1893 |
if (time) { |
c5780e976 [PATCH] Use the c... |
1894 |
to = &timeout; |
237fc6e7a add hrtimer speci... |
1895 1896 |
hrtimer_init_on_stack(&to->timer, CLOCK_REALTIME, HRTIMER_MODE_ABS); |
c5780e976 [PATCH] Use the c... |
1897 |
hrtimer_init_sleeper(to, current); |
cc584b213 hrtimer: convert ... |
1898 |
hrtimer_set_expires(&to->timer, *time); |
c5780e976 [PATCH] Use the c... |
1899 |
} |
42d35d48c futex: make futex... |
1900 |
retry: |
9ea71503a futex: Fix regres... |
1901 |
ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &q.key, VERIFY_WRITE); |
c87e2837b [PATCH] pi-futex:... |
1902 |
if (unlikely(ret != 0)) |
42d35d48c futex: make futex... |
1903 |
goto out; |
c87e2837b [PATCH] pi-futex:... |
1904 |
|
e4dc5b7a3 futex: clean up f... |
1905 |
retry_private: |
82af7aca5 Removal of FUTEX_FD |
1906 |
hb = queue_lock(&q); |
c87e2837b [PATCH] pi-futex:... |
1907 |
|
bab5bc9e8 futex: fixup unlo... |
1908 |
ret = futex_lock_pi_atomic(uaddr, hb, &q.key, &q.pi_state, current, 0); |
c87e2837b [PATCH] pi-futex:... |
1909 |
if (unlikely(ret)) { |
778e9a9c3 pi-futex: fix exi... |
1910 |
switch (ret) { |
1a52084d0 futex: split out ... |
1911 1912 1913 1914 1915 1916 |
case 1: /* We got the lock. */ ret = 0; goto out_unlock_put_key; case -EFAULT: goto uaddr_faulted; |
778e9a9c3 pi-futex: fix exi... |
1917 1918 1919 1920 1921 1922 |
case -EAGAIN: /* * Task is exiting and we just wait for the * exit to complete. */ queue_unlock(&q, hb); |
ae791a2d2 futex: Cleanup st... |
1923 |
put_futex_key(&q.key); |
778e9a9c3 pi-futex: fix exi... |
1924 1925 |
cond_resched(); goto retry; |
778e9a9c3 pi-futex: fix exi... |
1926 |
default: |
42d35d48c futex: make futex... |
1927 |
goto out_unlock_put_key; |
c87e2837b [PATCH] pi-futex:... |
1928 |
} |
c87e2837b [PATCH] pi-futex:... |
1929 1930 1931 1932 1933 |
} /* * Only actually queue now that the atomic ops are done: */ |
82af7aca5 Removal of FUTEX_FD |
1934 |
queue_me(&q, hb); |
c87e2837b [PATCH] pi-futex:... |
1935 |
|
c87e2837b [PATCH] pi-futex:... |
1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 |
WARN_ON(!q.pi_state); /* * Block on the PI mutex: */ if (!trylock) ret = rt_mutex_timed_lock(&q.pi_state->pi_mutex, to, 1); else { ret = rt_mutex_trylock(&q.pi_state->pi_mutex); /* Fixup the trylock return value: */ ret = ret ? 0 : -EWOULDBLOCK; } |
a99e4e413 [PATCH] pi-futex:... |
1947 |
spin_lock(q.lock_ptr); |
dd9739980 futex: split out ... |
1948 1949 1950 1951 |
/* * Fixup the pi_state owner and possibly acquire the lock if we * haven't already. */ |
ae791a2d2 futex: Cleanup st... |
1952 |
res = fixup_owner(uaddr, &q, !ret); |
dd9739980 futex: split out ... |
1953 1954 1955 1956 1957 1958 |
/* * 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:... |
1959 |
|
e8f6386c0 futex: unlock bef... |
1960 |
/* |
dd9739980 futex: split out ... |
1961 1962 |
* If fixup_owner() faulted and was unable to handle the fault, unlock * it and return the fault to userspace. |
e8f6386c0 futex: unlock bef... |
1963 1964 1965 |
*/ if (ret && (rt_mutex_owner(&q.pi_state->pi_mutex) == current)) rt_mutex_unlock(&q.pi_state->pi_mutex); |
778e9a9c3 pi-futex: fix exi... |
1966 1967 |
/* Unqueue and drop the lock */ unqueue_me_pi(&q); |
c87e2837b [PATCH] pi-futex:... |
1968 |
|
5ecb01cfd futex_lock_pi() k... |
1969 |
goto out_put_key; |
c87e2837b [PATCH] pi-futex:... |
1970 |
|
42d35d48c futex: make futex... |
1971 |
out_unlock_put_key: |
c87e2837b [PATCH] pi-futex:... |
1972 |
queue_unlock(&q, hb); |
42d35d48c futex: make futex... |
1973 |
out_put_key: |
ae791a2d2 futex: Cleanup st... |
1974 |
put_futex_key(&q.key); |
42d35d48c futex: make futex... |
1975 |
out: |
237fc6e7a add hrtimer speci... |
1976 1977 |
if (to) destroy_hrtimer_on_stack(&to->timer); |
dd9739980 futex: split out ... |
1978 |
return ret != -EINTR ? ret : -ERESTARTNOINTR; |
c87e2837b [PATCH] pi-futex:... |
1979 |
|
42d35d48c futex: make futex... |
1980 |
uaddr_faulted: |
778e9a9c3 pi-futex: fix exi... |
1981 |
queue_unlock(&q, hb); |
d0725992c futex: Fix the wr... |
1982 |
ret = fault_in_user_writeable(uaddr); |
e4dc5b7a3 futex: clean up f... |
1983 1984 |
if (ret) goto out_put_key; |
c87e2837b [PATCH] pi-futex:... |
1985 |
|
b41277dc7 futex: Replace fs... |
1986 |
if (!(flags & FLAGS_SHARED)) |
e4dc5b7a3 futex: clean up f... |
1987 |
goto retry_private; |
ae791a2d2 futex: Cleanup st... |
1988 |
put_futex_key(&q.key); |
e4dc5b7a3 futex: clean up f... |
1989 |
goto retry; |
c87e2837b [PATCH] pi-futex:... |
1990 1991 1992 |
} /* |
c87e2837b [PATCH] pi-futex:... |
1993 1994 1995 1996 |
* 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... |
1997 |
static int futex_unlock_pi(u32 __user *uaddr, unsigned int flags) |
c87e2837b [PATCH] pi-futex:... |
1998 1999 2000 |
{ struct futex_hash_bucket *hb; struct futex_q *this, *next; |
ec92d0829 futex priority ba... |
2001 |
struct plist_head *head; |
38d47c1b7 futex: rely on ge... |
2002 |
union futex_key key = FUTEX_KEY_INIT; |
c0c9ed150 futex: Avoid redu... |
2003 |
u32 uval, vpid = task_pid_vnr(current); |
e4dc5b7a3 futex: clean up f... |
2004 |
int ret; |
c87e2837b [PATCH] pi-futex:... |
2005 2006 2007 2008 2009 2010 2011 |
retry: if (get_user(uval, uaddr)) return -EFAULT; /* * We release only a lock we actually own: */ |
c0c9ed150 futex: Avoid redu... |
2012 |
if ((uval & FUTEX_TID_MASK) != vpid) |
c87e2837b [PATCH] pi-futex:... |
2013 |
return -EPERM; |
c87e2837b [PATCH] pi-futex:... |
2014 |
|
9ea71503a futex: Fix regres... |
2015 |
ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &key, VERIFY_WRITE); |
c87e2837b [PATCH] pi-futex:... |
2016 2017 2018 2019 2020 |
if (unlikely(ret != 0)) goto out; hb = hash_futex(&key); spin_lock(&hb->lock); |
c87e2837b [PATCH] pi-futex:... |
2021 2022 2023 2024 2025 |
/* * To avoid races, try to do the TID -> 0 atomic transition * again. If it succeeds then we can return without waking * anyone else up: */ |
37a9d912b futex: Sanitize c... |
2026 2027 |
if (!(uval & FUTEX_OWNER_DIED) && cmpxchg_futex_value_locked(&uval, uaddr, vpid, 0)) |
c87e2837b [PATCH] pi-futex:... |
2028 2029 2030 2031 2032 |
goto pi_faulted; /* * Rare case: we managed to release the lock atomically, * no need to wake anyone else up: */ |
c0c9ed150 futex: Avoid redu... |
2033 |
if (unlikely(uval == vpid)) |
c87e2837b [PATCH] pi-futex:... |
2034 2035 2036 2037 2038 2039 2040 |
goto out_unlock; /* * Ok, other tasks may need to be woken up - check waiters * and do the wakeup if necessary: */ head = &hb->chain; |
ec92d0829 futex priority ba... |
2041 |
plist_for_each_entry_safe(this, next, head, list) { |
c87e2837b [PATCH] pi-futex:... |
2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 |
if (!match_futex (&this->key, &key)) continue; ret = wake_futex_pi(uaddr, uval, this); /* * The atomic access to the futex value * generated a pagefault, so retry the * user-access and the wakeup: */ if (ret == -EFAULT) goto pi_faulted; goto out_unlock; } /* * No waiters - kernel unlocks the futex: */ |
e3f2ddeac [PATCH] pi-futex:... |
2057 2058 2059 2060 2061 |
if (!(uval & FUTEX_OWNER_DIED)) { ret = unlock_futex_pi(uaddr, uval); if (ret == -EFAULT) goto pi_faulted; } |
c87e2837b [PATCH] pi-futex:... |
2062 2063 2064 |
out_unlock: spin_unlock(&hb->lock); |
ae791a2d2 futex: Cleanup st... |
2065 |
put_futex_key(&key); |
c87e2837b [PATCH] pi-futex:... |
2066 |
|
42d35d48c futex: make futex... |
2067 |
out: |
c87e2837b [PATCH] pi-futex:... |
2068 2069 2070 |
return ret; pi_faulted: |
778e9a9c3 pi-futex: fix exi... |
2071 |
spin_unlock(&hb->lock); |
ae791a2d2 futex: Cleanup st... |
2072 |
put_futex_key(&key); |
c87e2837b [PATCH] pi-futex:... |
2073 |
|
d0725992c futex: Fix the wr... |
2074 |
ret = fault_in_user_writeable(uaddr); |
b56863630 futex: clean up f... |
2075 |
if (!ret) |
c87e2837b [PATCH] pi-futex:... |
2076 |
goto retry; |
1da177e4c Linux-2.6.12-rc2 |
2077 2078 |
return ret; } |
52400ba94 futex: add requeu... |
2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 |
/** * 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. * * Returns * 0 - no early wakeup detected |
1c840c149 futex: fix restar... |
2093 |
* <0 - -ETIMEDOUT or -ERESTARTNOINTR |
52400ba94 futex: add requeu... |
2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 |
*/ 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... |
2115 |
plist_del(&q->list, &hb->chain); |
52400ba94 futex: add requeu... |
2116 |
|
d58e6576b futex: Handle spu... |
2117 |
/* Handle spurious wakeups gracefully */ |
11df6dddc futex: Fix spurio... |
2118 |
ret = -EWOULDBLOCK; |
52400ba94 futex: add requeu... |
2119 2120 |
if (timeout && !timeout->task) ret = -ETIMEDOUT; |
d58e6576b futex: Handle spu... |
2121 |
else if (signal_pending(current)) |
1c840c149 futex: fix restar... |
2122 |
ret = -ERESTARTNOINTR; |
52400ba94 futex: add requeu... |
2123 2124 2125 2126 2127 2128 |
} return ret; } /** * futex_wait_requeue_pi() - Wait on uaddr and take uaddr2 |
56ec1607b futex: Correct fu... |
2129 |
* @uaddr: the futex we initially wait on (non-pi) |
b41277dc7 futex: Replace fs... |
2130 |
* @flags: futex flags (FLAGS_SHARED, FLAGS_CLOCKRT, etc.), they must be |
52400ba94 futex: add requeu... |
2131 2132 2133 |
* the same type, no requeueing from private to shared, etc. * @val: the expected value of uaddr * @abs_time: absolute timeout |
56ec1607b futex: Correct fu... |
2134 |
* @bitset: 32 bit wakeup bitset set by userspace, defaults to all |
52400ba94 futex: add requeu... |
2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 |
* @clockrt: whether to use CLOCK_REALTIME (1) or CLOCK_MONOTONIC (0) * @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 * uaddr2 which must be PI aware. 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 wouldn't know which task to boost/deboost, if there was a * need to. * * We call schedule in futex_wait_queue_me() when we enqueue and return there * via the following: * 1) wakeup on uaddr2 after an atomic lock acquisition by futex_requeue() |
cc6db4e60 futex: Correct fu... |
2148 2149 2150 |
* 2) wakeup on uaddr2 after a requeue * 3) signal * 4) timeout |
52400ba94 futex: add requeu... |
2151 |
* |
cc6db4e60 futex: Correct fu... |
2152 |
* If 3, cleanup and return -ERESTARTNOINTR. |
52400ba94 futex: add requeu... |
2153 2154 2155 2156 2157 2158 2159 |
* * 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... |
2160 |
* If 6, return -EWOULDBLOCK (restarting the syscall would do the same). |
52400ba94 futex: add requeu... |
2161 2162 2163 2164 2165 2166 2167 |
* * If 4 or 7, we cleanup and return with -ETIMEDOUT. * * Returns: * 0 - On success * <0 - On error */ |
b41277dc7 futex: Replace fs... |
2168 |
static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags, |
52400ba94 futex: add requeu... |
2169 |
u32 val, ktime_t *abs_time, u32 bitset, |
b41277dc7 futex: Replace fs... |
2170 |
u32 __user *uaddr2) |
52400ba94 futex: add requeu... |
2171 2172 2173 2174 |
{ struct hrtimer_sleeper timeout, *to = NULL; struct rt_mutex_waiter rt_waiter; struct rt_mutex *pi_mutex = NULL; |
52400ba94 futex: add requeu... |
2175 |
struct futex_hash_bucket *hb; |
5bdb05f91 futex: Add futex_... |
2176 2177 |
union futex_key key2 = FUTEX_KEY_INIT; struct futex_q q = futex_q_init; |
52400ba94 futex: add requeu... |
2178 |
int res, ret; |
52400ba94 futex: add requeu... |
2179 2180 2181 2182 2183 2184 |
if (!bitset) return -EINVAL; if (abs_time) { to = &timeout; |
b41277dc7 futex: Replace fs... |
2185 2186 2187 |
hrtimer_init_on_stack(&to->timer, (flags & FLAGS_CLOCKRT) ? CLOCK_REALTIME : CLOCK_MONOTONIC, HRTIMER_MODE_ABS); |
52400ba94 futex: add requeu... |
2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 |
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. */ debug_rt_mutex_init_waiter(&rt_waiter); rt_waiter.task = NULL; |
9ea71503a futex: Fix regres... |
2199 |
ret = get_futex_key(uaddr2, flags & FLAGS_SHARED, &key2, VERIFY_WRITE); |
52400ba94 futex: add requeu... |
2200 2201 |
if (unlikely(ret != 0)) goto out; |
84bc4af59 futex: Detect mis... |
2202 2203 2204 |
q.bitset = bitset; q.rt_waiter = &rt_waiter; q.requeue_pi_key = &key2; |
7ada876a8 futex: Fix errors... |
2205 2206 2207 2208 |
/* * Prepare to wait on uaddr. On success, increments q.key (key1) ref * count. */ |
b41277dc7 futex: Replace fs... |
2209 |
ret = futex_wait_setup(uaddr, val, flags, &q, &hb); |
c8b15a706 futex: cleanup er... |
2210 2211 |
if (ret) goto out_key2; |
52400ba94 futex: add requeu... |
2212 2213 |
/* Queue the futex_q, drop the hb lock, wait for wakeup. */ |
f1a11e057 futex: remove the... |
2214 |
futex_wait_queue_me(hb, &q, to); |
52400ba94 futex: add requeu... |
2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 |
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... |
2226 2227 2228 |
* 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... |
2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 |
*/ /* 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... |
2239 |
ret = fixup_pi_state_owner(uaddr2, &q, current); |
52400ba94 futex: add requeu... |
2240 2241 2242 2243 2244 2245 2246 2247 2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 |
spin_unlock(q.lock_ptr); } } else { /* * 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. */ WARN_ON(!&q.pi_state); pi_mutex = &q.pi_state->pi_mutex; ret = rt_mutex_finish_proxy_lock(pi_mutex, to, &rt_waiter, 1); debug_rt_mutex_free_waiter(&rt_waiter); spin_lock(q.lock_ptr); /* * Fixup the pi_state owner and possibly acquire the lock if we * haven't already. */ |
ae791a2d2 futex: Cleanup st... |
2258 |
res = fixup_owner(uaddr2, &q, !ret); |
52400ba94 futex: add requeu... |
2259 2260 |
/* * If fixup_owner() returned an error, proprogate that. If it |
56ec1607b futex: Correct fu... |
2261 |
* acquired the lock, clear -ETIMEDOUT or -EINTR. |
52400ba94 futex: add requeu... |
2262 2263 2264 2265 2266 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 |
*/ if (res) ret = (res < 0) ? res : 0; /* Unqueue and drop the lock. */ unqueue_me_pi(&q); } /* * If fixup_pi_state_owner() faulted and was unable to handle the * fault, unlock the rt_mutex and return the fault to userspace. */ if (ret == -EFAULT) { if (rt_mutex_owner(pi_mutex) == current) rt_mutex_unlock(pi_mutex); } else if (ret == -EINTR) { |
52400ba94 futex: add requeu... |
2278 |
/* |
cc6db4e60 futex: Correct fu... |
2279 2280 2281 2282 2283 |
* 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... |
2284 |
*/ |
2070887fd futex: fix restar... |
2285 |
ret = -EWOULDBLOCK; |
52400ba94 futex: add requeu... |
2286 2287 2288 |
} out_put_keys: |
ae791a2d2 futex: Cleanup st... |
2289 |
put_futex_key(&q.key); |
c8b15a706 futex: cleanup er... |
2290 |
out_key2: |
ae791a2d2 futex: Cleanup st... |
2291 |
put_futex_key(&key2); |
52400ba94 futex: add requeu... |
2292 2293 2294 2295 2296 2297 2298 2299 |
out: if (to) { hrtimer_cancel(&to->timer); destroy_hrtimer_on_stack(&to->timer); } return ret; } |
0771dfefc [PATCH] lightweig... |
2300 2301 2302 2303 2304 2305 2306 |
/* * 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:... |
2307 |
* FUTEX_OWNER_DIED bit, and wakes up a waiter (if any). The list is |
0771dfefc [PATCH] lightweig... |
2308 2309 2310 2311 2312 2313 2314 2315 |
* 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... |
2316 2317 2318 |
* 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... |
2319 |
*/ |
836f92adf [CVE-2009-0029] S... |
2320 2321 |
SYSCALL_DEFINE2(set_robust_list, struct robust_list_head __user *, head, size_t, len) |
0771dfefc [PATCH] lightweig... |
2322 |
{ |
a0c1e9073 futex: runtime en... |
2323 2324 |
if (!futex_cmpxchg_enabled) return -ENOSYS; |
0771dfefc [PATCH] lightweig... |
2325 2326 2327 2328 2329 2330 2331 2332 2333 2334 2335 2336 |
/* * 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... |
2337 2338 2339 2340 |
* 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... |
2341 |
*/ |
836f92adf [CVE-2009-0029] S... |
2342 2343 2344 |
SYSCALL_DEFINE3(get_robust_list, int, pid, struct robust_list_head __user * __user *, head_ptr, size_t __user *, len_ptr) |
0771dfefc [PATCH] lightweig... |
2345 |
{ |
ba46df984 [PATCH] __user an... |
2346 |
struct robust_list_head __user *head; |
0771dfefc [PATCH] lightweig... |
2347 |
unsigned long ret; |
c69e8d9c0 CRED: Use RCU to ... |
2348 |
const struct cred *cred = current_cred(), *pcred; |
0771dfefc [PATCH] lightweig... |
2349 |
|
a0c1e9073 futex: runtime en... |
2350 2351 |
if (!futex_cmpxchg_enabled) return -ENOSYS; |
0771dfefc [PATCH] lightweig... |
2352 2353 2354 2355 2356 2357 |
if (!pid) head = current->robust_list; else { struct task_struct *p; ret = -ESRCH; |
aaa2a97eb [PATCH] sys_get_r... |
2358 |
rcu_read_lock(); |
228ebcbe6 Uninline find_tas... |
2359 |
p = find_task_by_vpid(pid); |
0771dfefc [PATCH] lightweig... |
2360 2361 2362 |
if (!p) goto err_unlock; ret = -EPERM; |
c69e8d9c0 CRED: Use RCU to ... |
2363 |
pcred = __task_cred(p); |
b0e77598f userns: user name... |
2364 2365 2366 2367 2368 2369 2370 2371 |
/* If victim is in different user_ns, then uids are not comparable, so we must have CAP_SYS_PTRACE */ if (cred->user->user_ns != pcred->user->user_ns) { if (!ns_capable(pcred->user->user_ns, CAP_SYS_PTRACE)) goto err_unlock; goto ok; } /* If victim is in same user_ns, then uids are comparable */ |
c69e8d9c0 CRED: Use RCU to ... |
2372 2373 |
if (cred->euid != pcred->euid && cred->euid != pcred->uid && |
b0e77598f userns: user name... |
2374 |
!ns_capable(pcred->user->user_ns, CAP_SYS_PTRACE)) |
0771dfefc [PATCH] lightweig... |
2375 |
goto err_unlock; |
b0e77598f userns: user name... |
2376 |
ok: |
0771dfefc [PATCH] lightweig... |
2377 |
head = p->robust_list; |
aaa2a97eb [PATCH] sys_get_r... |
2378 |
rcu_read_unlock(); |
0771dfefc [PATCH] lightweig... |
2379 2380 2381 2382 2383 2384 2385 |
} if (put_user(sizeof(*head), len_ptr)) return -EFAULT; return put_user(head, head_ptr); err_unlock: |
aaa2a97eb [PATCH] sys_get_r... |
2386 |
rcu_read_unlock(); |
0771dfefc [PATCH] lightweig... |
2387 2388 2389 2390 2391 2392 2393 2394 |
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:... |
2395 |
int handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi) |
0771dfefc [PATCH] lightweig... |
2396 |
{ |
7cfdaf38d futex: uninitiali... |
2397 |
u32 uval, uninitialized_var(nval), mval; |
0771dfefc [PATCH] lightweig... |
2398 |
|
8f17d3a50 [PATCH] lightweig... |
2399 2400 |
retry: if (get_user(uval, uaddr)) |
0771dfefc [PATCH] lightweig... |
2401 |
return -1; |
b488893a3 pid namespaces: c... |
2402 |
if ((uval & FUTEX_TID_MASK) == task_pid_vnr(curr)) { |
0771dfefc [PATCH] lightweig... |
2403 2404 2405 2406 2407 2408 2409 2410 2411 2412 |
/* * 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:... |
2413 |
mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED; |
6e0aa9f8a futex: Deobfuscat... |
2414 2415 2416 2417 2418 2419 2420 2421 2422 2423 2424 2425 2426 2427 |
/* * 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:... |
2428 |
if (nval != uval) |
8f17d3a50 [PATCH] lightweig... |
2429 |
goto retry; |
0771dfefc [PATCH] lightweig... |
2430 |
|
e3f2ddeac [PATCH] pi-futex:... |
2431 2432 2433 2434 |
/* * Wake robust non-PI futexes here. The wakeup of * PI futexes happens in exit_pi_state(): */ |
36cf3b5c3 FUTEX: Tidy up th... |
2435 |
if (!pi && (uval & FUTEX_WAITERS)) |
c2f9f2015 futex: cleanup fs... |
2436 |
futex_wake(uaddr, 1, 1, FUTEX_BITSET_MATCH_ANY); |
0771dfefc [PATCH] lightweig... |
2437 2438 2439 2440 2441 |
} return 0; } /* |
e3f2ddeac [PATCH] pi-futex:... |
2442 2443 2444 |
* 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... |
2445 |
struct robust_list __user * __user *head, |
1dcc41bb0 futex: Change 3rd... |
2446 |
unsigned int *pi) |
e3f2ddeac [PATCH] pi-futex:... |
2447 2448 |
{ unsigned long uentry; |
ba46df984 [PATCH] __user an... |
2449 |
if (get_user(uentry, (unsigned long __user *)head)) |
e3f2ddeac [PATCH] pi-futex:... |
2450 |
return -EFAULT; |
ba46df984 [PATCH] __user an... |
2451 |
*entry = (void __user *)(uentry & ~1UL); |
e3f2ddeac [PATCH] pi-futex:... |
2452 2453 2454 2455 2456 2457 |
*pi = uentry & 1; return 0; } /* |
0771dfefc [PATCH] lightweig... |
2458 2459 2460 2461 2462 2463 2464 2465 |
* 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... |
2466 |
struct robust_list __user *entry, *next_entry, *pending; |
4c115e951 futex: Address co... |
2467 2468 |
unsigned int limit = ROBUST_LIST_LIMIT, pi, pip; unsigned int uninitialized_var(next_pi); |
0771dfefc [PATCH] lightweig... |
2469 |
unsigned long futex_offset; |
9f96cb1e8 robust futex thre... |
2470 |
int rc; |
0771dfefc [PATCH] lightweig... |
2471 |
|
a0c1e9073 futex: runtime en... |
2472 2473 |
if (!futex_cmpxchg_enabled) return; |
0771dfefc [PATCH] lightweig... |
2474 2475 2476 2477 |
/* * Fetch the list head (which was registered earlier, via * sys_set_robust_list()): */ |
e3f2ddeac [PATCH] pi-futex:... |
2478 |
if (fetch_robust_entry(&entry, &head->list.next, &pi)) |
0771dfefc [PATCH] lightweig... |
2479 2480 2481 2482 2483 2484 2485 2486 2487 2488 |
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:... |
2489 |
if (fetch_robust_entry(&pending, &head->list_op_pending, &pip)) |
0771dfefc [PATCH] lightweig... |
2490 |
return; |
e3f2ddeac [PATCH] pi-futex:... |
2491 |
|
9f96cb1e8 robust futex thre... |
2492 |
next_entry = NULL; /* avoid warning with gcc */ |
0771dfefc [PATCH] lightweig... |
2493 2494 |
while (entry != &head->list) { /* |
9f96cb1e8 robust futex thre... |
2495 2496 2497 2498 2499 |
* 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... |
2500 |
* A pending lock might already be on the list, so |
c87e2837b [PATCH] pi-futex:... |
2501 |
* don't process it twice: |
0771dfefc [PATCH] lightweig... |
2502 2503 |
*/ if (entry != pending) |
ba46df984 [PATCH] __user an... |
2504 |
if (handle_futex_death((void __user *)entry + futex_offset, |
e3f2ddeac [PATCH] pi-futex:... |
2505 |
curr, pi)) |
0771dfefc [PATCH] lightweig... |
2506 |
return; |
9f96cb1e8 robust futex thre... |
2507 |
if (rc) |
0771dfefc [PATCH] lightweig... |
2508 |
return; |
9f96cb1e8 robust futex thre... |
2509 2510 |
entry = next_entry; pi = next_pi; |
0771dfefc [PATCH] lightweig... |
2511 2512 2513 2514 2515 2516 2517 2518 |
/* * Avoid excessively long or circular lists: */ if (!--limit) break; cond_resched(); } |
9f96cb1e8 robust futex thre... |
2519 2520 2521 2522 |
if (pending) handle_futex_death((void __user *)pending + futex_offset, curr, pip); |
0771dfefc [PATCH] lightweig... |
2523 |
} |
c19384b5b Make futex_wait()... |
2524 |
long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout, |
e2970f2fb [PATCH] pi-futex:... |
2525 |
u32 __user *uaddr2, u32 val2, u32 val3) |
1da177e4c Linux-2.6.12-rc2 |
2526 |
{ |
b41277dc7 futex: Replace fs... |
2527 2528 |
int ret = -ENOSYS, cmd = op & FUTEX_CMD_MASK; unsigned int flags = 0; |
34f01cc1f FUTEX: new PRIVAT... |
2529 2530 |
if (!(op & FUTEX_PRIVATE_FLAG)) |
b41277dc7 futex: Replace fs... |
2531 |
flags |= FLAGS_SHARED; |
1da177e4c Linux-2.6.12-rc2 |
2532 |
|
b41277dc7 futex: Replace fs... |
2533 2534 2535 2536 2537 |
if (op & FUTEX_CLOCK_REALTIME) { flags |= FLAGS_CLOCKRT; if (cmd != FUTEX_WAIT_BITSET && cmd != FUTEX_WAIT_REQUEUE_PI) return -ENOSYS; } |
1da177e4c Linux-2.6.12-rc2 |
2538 |
|
34f01cc1f FUTEX: new PRIVAT... |
2539 |
switch (cmd) { |
1da177e4c Linux-2.6.12-rc2 |
2540 |
case FUTEX_WAIT: |
cd689985c futex: Add bitset... |
2541 2542 |
val3 = FUTEX_BITSET_MATCH_ANY; case FUTEX_WAIT_BITSET: |
b41277dc7 futex: Replace fs... |
2543 |
ret = futex_wait(uaddr, flags, val, timeout, val3); |
1da177e4c Linux-2.6.12-rc2 |
2544 2545 |
break; case FUTEX_WAKE: |
cd689985c futex: Add bitset... |
2546 2547 |
val3 = FUTEX_BITSET_MATCH_ANY; case FUTEX_WAKE_BITSET: |
b41277dc7 futex: Replace fs... |
2548 |
ret = futex_wake(uaddr, flags, val, val3); |
1da177e4c Linux-2.6.12-rc2 |
2549 |
break; |
1da177e4c Linux-2.6.12-rc2 |
2550 |
case FUTEX_REQUEUE: |
b41277dc7 futex: Replace fs... |
2551 |
ret = futex_requeue(uaddr, flags, uaddr2, val, val2, NULL, 0); |
1da177e4c Linux-2.6.12-rc2 |
2552 2553 |
break; case FUTEX_CMP_REQUEUE: |
b41277dc7 futex: Replace fs... |
2554 |
ret = futex_requeue(uaddr, flags, uaddr2, val, val2, &val3, 0); |
1da177e4c Linux-2.6.12-rc2 |
2555 |
break; |
4732efbeb [PATCH] FUTEX_WAK... |
2556 |
case FUTEX_WAKE_OP: |
b41277dc7 futex: Replace fs... |
2557 |
ret = futex_wake_op(uaddr, flags, uaddr2, val, val2, val3); |
4732efbeb [PATCH] FUTEX_WAK... |
2558 |
break; |
c87e2837b [PATCH] pi-futex:... |
2559 |
case FUTEX_LOCK_PI: |
a0c1e9073 futex: runtime en... |
2560 |
if (futex_cmpxchg_enabled) |
b41277dc7 futex: Replace fs... |
2561 |
ret = futex_lock_pi(uaddr, flags, val, timeout, 0); |
c87e2837b [PATCH] pi-futex:... |
2562 2563 |
break; case FUTEX_UNLOCK_PI: |
a0c1e9073 futex: runtime en... |
2564 |
if (futex_cmpxchg_enabled) |
b41277dc7 futex: Replace fs... |
2565 |
ret = futex_unlock_pi(uaddr, flags); |
c87e2837b [PATCH] pi-futex:... |
2566 2567 |
break; case FUTEX_TRYLOCK_PI: |
a0c1e9073 futex: runtime en... |
2568 |
if (futex_cmpxchg_enabled) |
b41277dc7 futex: Replace fs... |
2569 |
ret = futex_lock_pi(uaddr, flags, 0, timeout, 1); |
c87e2837b [PATCH] pi-futex:... |
2570 |
break; |
52400ba94 futex: add requeu... |
2571 2572 |
case FUTEX_WAIT_REQUEUE_PI: val3 = FUTEX_BITSET_MATCH_ANY; |
b41277dc7 futex: Replace fs... |
2573 2574 |
ret = futex_wait_requeue_pi(uaddr, flags, val, timeout, val3, uaddr2); |
52400ba94 futex: add requeu... |
2575 |
break; |
52400ba94 futex: add requeu... |
2576 |
case FUTEX_CMP_REQUEUE_PI: |
b41277dc7 futex: Replace fs... |
2577 |
ret = futex_requeue(uaddr, flags, uaddr2, val, val2, &val3, 1); |
52400ba94 futex: add requeu... |
2578 |
break; |
1da177e4c Linux-2.6.12-rc2 |
2579 2580 2581 2582 2583 |
default: ret = -ENOSYS; } return ret; } |
17da2bd90 [CVE-2009-0029] S... |
2584 2585 2586 |
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 |
2587 |
{ |
c19384b5b Make futex_wait()... |
2588 2589 |
struct timespec ts; ktime_t t, *tp = NULL; |
e2970f2fb [PATCH] pi-futex:... |
2590 |
u32 val2 = 0; |
34f01cc1f FUTEX: new PRIVAT... |
2591 |
int cmd = op & FUTEX_CMD_MASK; |
1da177e4c Linux-2.6.12-rc2 |
2592 |
|
cd689985c futex: Add bitset... |
2593 |
if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI || |
52400ba94 futex: add requeu... |
2594 2595 |
cmd == FUTEX_WAIT_BITSET || cmd == FUTEX_WAIT_REQUEUE_PI)) { |
c19384b5b Make futex_wait()... |
2596 |
if (copy_from_user(&ts, utime, sizeof(ts)) != 0) |
1da177e4c Linux-2.6.12-rc2 |
2597 |
return -EFAULT; |
c19384b5b Make futex_wait()... |
2598 |
if (!timespec_valid(&ts)) |
9741ef964 [PATCH] futex: ch... |
2599 |
return -EINVAL; |
c19384b5b Make futex_wait()... |
2600 2601 |
t = timespec_to_ktime(ts); |
34f01cc1f FUTEX: new PRIVAT... |
2602 |
if (cmd == FUTEX_WAIT) |
5a7780e72 hrtimer: check re... |
2603 |
t = ktime_add_safe(ktime_get(), t); |
c19384b5b Make futex_wait()... |
2604 |
tp = &t; |
1da177e4c Linux-2.6.12-rc2 |
2605 2606 |
} /* |
52400ba94 futex: add requeu... |
2607 |
* requeue parameter in 'utime' if cmd == FUTEX_*_REQUEUE_*. |
f54f09861 futex: pass nr_wa... |
2608 |
* number of waiters to wake in 'utime' if cmd == FUTEX_WAKE_OP. |
1da177e4c Linux-2.6.12-rc2 |
2609 |
*/ |
f54f09861 futex: pass nr_wa... |
2610 |
if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE || |
ba9c22f2c futex: remove FUT... |
2611 |
cmd == FUTEX_CMP_REQUEUE_PI || cmd == FUTEX_WAKE_OP) |
e2970f2fb [PATCH] pi-futex:... |
2612 |
val2 = (u32) (unsigned long) utime; |
1da177e4c Linux-2.6.12-rc2 |
2613 |
|
c19384b5b Make futex_wait()... |
2614 |
return do_futex(uaddr, op, val, tp, uaddr2, val2, val3); |
1da177e4c Linux-2.6.12-rc2 |
2615 |
} |
f6d107fb1 Give futex init a... |
2616 |
static int __init futex_init(void) |
1da177e4c Linux-2.6.12-rc2 |
2617 |
{ |
a0c1e9073 futex: runtime en... |
2618 |
u32 curval; |
3e4ab747e futex: fix init o... |
2619 |
int i; |
95362fa90 [PATCH] futex: in... |
2620 |
|
a0c1e9073 futex: runtime en... |
2621 2622 2623 2624 2625 2626 2627 |
/* * 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 |
fb62db2ba futex: Fix kernel... |
2628 |
* implementation, the non-functional ones will return |
a0c1e9073 futex: runtime en... |
2629 2630 |
* -ENOSYS. */ |
37a9d912b futex: Sanitize c... |
2631 |
if (cmpxchg_futex_value_locked(&curval, NULL, 0, 0) == -EFAULT) |
a0c1e9073 futex: runtime en... |
2632 |
futex_cmpxchg_enabled = 1; |
3e4ab747e futex: fix init o... |
2633 |
for (i = 0; i < ARRAY_SIZE(futex_queues); i++) { |
732375c6a plist: Remove the... |
2634 |
plist_head_init(&futex_queues[i].chain); |
3e4ab747e futex: fix init o... |
2635 2636 |
spin_lock_init(&futex_queues[i].lock); } |
1da177e4c Linux-2.6.12-rc2 |
2637 2638 |
return 0; } |
f6d107fb1 Give futex init a... |
2639 |
__initcall(futex_init); |