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fs/eventpoll.c
57.6 KB
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/* |
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* fs/eventpoll.c (Efficient event retrieval implementation) * Copyright (C) 2001,...,2009 Davide Libenzi |
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* * 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. * * Davide Libenzi <davidel@xmailserver.org> * */ |
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#include <linux/init.h> #include <linux/kernel.h> #include <linux/sched.h> #include <linux/fs.h> #include <linux/file.h> #include <linux/signal.h> #include <linux/errno.h> #include <linux/mm.h> #include <linux/slab.h> #include <linux/poll.h> |
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#include <linux/string.h> #include <linux/list.h> #include <linux/hash.h> #include <linux/spinlock.h> #include <linux/syscalls.h> |
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#include <linux/rbtree.h> #include <linux/wait.h> #include <linux/eventpoll.h> #include <linux/mount.h> #include <linux/bitops.h> |
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#include <linux/mutex.h> |
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#include <linux/anon_inodes.h> |
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#include <linux/device.h> |
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#include <linux/freezer.h> |
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#include <asm/uaccess.h> |
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#include <asm/io.h> #include <asm/mman.h> |
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#include <linux/atomic.h> |
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#include <linux/proc_fs.h> #include <linux/seq_file.h> |
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#include <linux/compat.h> |
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|
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/* * LOCKING: * There are three level of locking required by epoll : * |
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* 1) epmutex (mutex) |
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* 2) ep->mtx (mutex) * 3) ep->lock (spinlock) |
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* * The acquire order is the one listed above, from 1 to 3. * We need a spinlock (ep->lock) because we manipulate objects * from inside the poll callback, that might be triggered from * a wake_up() that in turn might be called from IRQ context. * So we can't sleep inside the poll callback and hence we need * a spinlock. During the event transfer loop (from kernel to * user space) we could end up sleeping due a copy_to_user(), so * we need a lock that will allow us to sleep. This lock is a |
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* mutex (ep->mtx). It is acquired during the event transfer loop, * during epoll_ctl(EPOLL_CTL_DEL) and during eventpoll_release_file(). * Then we also need a global mutex to serialize eventpoll_release_file() * and ep_free(). * This mutex is acquired by ep_free() during the epoll file |
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* cleanup path and it is also acquired by eventpoll_release_file() * if a file has been pushed inside an epoll set and it is then |
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* close()d without a previous call to epoll_ctl(EPOLL_CTL_DEL). |
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* It is also acquired when inserting an epoll fd onto another epoll * fd. We do this so that we walk the epoll tree and ensure that this * insertion does not create a cycle of epoll file descriptors, which * could lead to deadlock. We need a global mutex to prevent two * simultaneous inserts (A into B and B into A) from racing and * constructing a cycle without either insert observing that it is * going to. |
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* It is necessary to acquire multiple "ep->mtx"es at once in the * case when one epoll fd is added to another. In this case, we * always acquire the locks in the order of nesting (i.e. after * epoll_ctl(e1, EPOLL_CTL_ADD, e2), e1->mtx will always be acquired * before e2->mtx). Since we disallow cycles of epoll file * descriptors, this ensures that the mutexes are well-ordered. In * order to communicate this nesting to lockdep, when walking a tree * of epoll file descriptors, we use the current recursion depth as * the lockdep subkey. |
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* It is possible to drop the "ep->mtx" and to use the global * mutex "epmutex" (together with "ep->lock") to have it working, * but having "ep->mtx" will make the interface more scalable. |
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* Events that require holding "epmutex" are very rare, while for |
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* normal operations the epoll private "ep->mtx" will guarantee * a better scalability. |
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*/ |
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/* Epoll private bits inside the event mask */ |
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#define EP_PRIVATE_BITS (EPOLLWAKEUP | EPOLLONESHOT | EPOLLET) |
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|
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/* Maximum number of nesting allowed inside epoll sets */ #define EP_MAX_NESTS 4 |
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|
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#define EP_MAX_EVENTS (INT_MAX / sizeof(struct epoll_event)) |
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#define EP_UNACTIVE_PTR ((void *) -1L) |
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#define EP_ITEM_COST (sizeof(struct epitem) + sizeof(struct eppoll_entry)) |
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struct epoll_filefd { struct file *file; int fd; |
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} __packed; |
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/* |
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* Structure used to track possible nested calls, for too deep recursions * and loop cycles. |
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*/ |
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struct nested_call_node { |
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struct list_head llink; |
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void *cookie; |
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void *ctx; |
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}; /* |
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* This structure is used as collector for nested calls, to check for * maximum recursion dept and loop cycles. |
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*/ |
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struct nested_calls { struct list_head tasks_call_list; |
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spinlock_t lock; }; /* |
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* Each file descriptor added to the eventpoll interface will * have an entry of this type linked to the "rbr" RB tree. |
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* Avoid increasing the size of this struct, there can be many thousands * of these on a server and we do not want this to take another cache line. |
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*/ struct epitem { |
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/* RB tree node used to link this structure to the eventpoll RB tree */ |
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struct rb_node rbn; /* List header used to link this structure to the eventpoll ready list */ struct list_head rdllink; |
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/* * Works together "struct eventpoll"->ovflist in keeping the * single linked chain of items. */ struct epitem *next; |
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/* The file descriptor information this item refers to */ struct epoll_filefd ffd; /* Number of active wait queue attached to poll operations */ int nwait; /* List containing poll wait queues */ struct list_head pwqlist; /* The "container" of this item */ struct eventpoll *ep; |
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/* List header used to link this item to the "struct file" items list */ struct list_head fllink; |
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/* wakeup_source used when EPOLLWAKEUP is set */ |
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struct wakeup_source __rcu *ws; |
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|
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/* The structure that describe the interested events and the source fd */ struct epoll_event event; |
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}; /* |
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* This structure is stored inside the "private_data" member of the file |
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* structure and represents the main data structure for the eventpoll |
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* interface. */ struct eventpoll { |
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/* Protect the access to this structure */ |
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spinlock_t lock; |
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/* |
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* This mutex is used to ensure that files are not removed * while epoll is using them. This is held during the event * collection loop, the file cleanup path, the epoll file exit * code and the ctl operations. |
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*/ |
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struct mutex mtx; |
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/* Wait queue used by sys_epoll_wait() */ wait_queue_head_t wq; /* Wait queue used by file->poll() */ wait_queue_head_t poll_wait; /* List of ready file descriptors */ struct list_head rdllist; |
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/* RB tree root used to store monitored fd structs */ |
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struct rb_root rbr; |
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/* * This is a single linked list that chains all the "struct epitem" that |
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* happened while transferring ready events to userspace w/out |
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* holding ->lock. */ struct epitem *ovflist; |
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|
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/* wakeup_source used when ep_scan_ready_list is running */ struct wakeup_source *ws; |
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/* The user that created the eventpoll descriptor */ struct user_struct *user; |
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struct file *file; /* used to optimize loop detection check */ int visited; struct list_head visited_list_link; |
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}; /* Wait structure used by the poll hooks */ struct eppoll_entry { /* List header used to link this structure to the "struct epitem" */ struct list_head llink; /* The "base" pointer is set to the container "struct epitem" */ |
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struct epitem *base; |
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/* * Wait queue item that will be linked to the target file wait * queue head. */ wait_queue_t wait; /* The wait queue head that linked the "wait" wait queue item */ wait_queue_head_t *whead; }; |
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/* Wrapper struct used by poll queueing */ struct ep_pqueue { poll_table pt; struct epitem *epi; }; |
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/* Used by the ep_send_events() function as callback private data */ struct ep_send_events_data { int maxevents; struct epoll_event __user *events; }; |
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/* |
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* Configuration options available inside /proc/sys/fs/epoll/ */ |
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/* Maximum number of epoll watched descriptors, per user */ |
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static long max_user_watches __read_mostly; |
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/* |
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* This mutex is used to serialize ep_free() and eventpoll_release_file(). |
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*/ |
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static DEFINE_MUTEX(epmutex); |
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|
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/* Used to check for epoll file descriptor inclusion loops */ static struct nested_calls poll_loop_ncalls; |
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/* Used for safe wake up implementation */ static struct nested_calls poll_safewake_ncalls; /* Used to call file's f_op->poll() under the nested calls boundaries */ static struct nested_calls poll_readywalk_ncalls; |
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/* Slab cache used to allocate "struct epitem" */ |
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static struct kmem_cache *epi_cache __read_mostly; |
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/* Slab cache used to allocate "struct eppoll_entry" */ |
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static struct kmem_cache *pwq_cache __read_mostly; |
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|
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/* Visited nodes during ep_loop_check(), so we can unset them when we finish */ static LIST_HEAD(visited_list); /* * List of files with newly added links, where we may need to limit the number * of emanating paths. Protected by the epmutex. */ static LIST_HEAD(tfile_check_list); |
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#ifdef CONFIG_SYSCTL #include <linux/sysctl.h> |
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static long zero; static long long_max = LONG_MAX; |
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ctl_table epoll_table[] = { { |
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.procname = "max_user_watches", .data = &max_user_watches, |
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.maxlen = sizeof(max_user_watches), |
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.mode = 0644, |
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.proc_handler = proc_doulongvec_minmax, |
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.extra1 = &zero, |
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.extra2 = &long_max, |
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}, |
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{ } |
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}; #endif /* CONFIG_SYSCTL */ |
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static const struct file_operations eventpoll_fops; static inline int is_file_epoll(struct file *f) { return f->f_op == &eventpoll_fops; } |
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|
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/* Setup the structure that is used as key for the RB tree */ |
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static inline void ep_set_ffd(struct epoll_filefd *ffd, struct file *file, int fd) { ffd->file = file; ffd->fd = fd; } |
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/* Compare RB tree keys */ |
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static inline int ep_cmp_ffd(struct epoll_filefd *p1, struct epoll_filefd *p2) { return (p1->file > p2->file ? +1: (p1->file < p2->file ? -1 : p1->fd - p2->fd)); } |
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/* Tells us if the item is currently linked */ static inline int ep_is_linked(struct list_head *p) { return !list_empty(p); } |
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static inline struct eppoll_entry *ep_pwq_from_wait(wait_queue_t *p) { return container_of(p, struct eppoll_entry, wait); } |
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/* Get the "struct epitem" from a wait queue pointer */ |
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static inline struct epitem *ep_item_from_wait(wait_queue_t *p) |
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{ return container_of(p, struct eppoll_entry, wait)->base; } /* Get the "struct epitem" from an epoll queue wrapper */ |
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static inline struct epitem *ep_item_from_epqueue(poll_table *p) |
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{ return container_of(p, struct ep_pqueue, pt)->epi; } /* Tells if the epoll_ctl(2) operation needs an event copy from userspace */ |
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static inline int ep_op_has_event(int op) |
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{ |
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return op != EPOLL_CTL_DEL; |
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} |
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/* Initialize the poll safe wake up structure */ |
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static void ep_nested_calls_init(struct nested_calls *ncalls) |
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{ |
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INIT_LIST_HEAD(&ncalls->tasks_call_list); spin_lock_init(&ncalls->lock); |
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} |
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/** |
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* ep_events_available - Checks if ready events might be available. * * @ep: Pointer to the eventpoll context. * * Returns: Returns a value different than zero if ready events are available, * or zero otherwise. */ static inline int ep_events_available(struct eventpoll *ep) { return !list_empty(&ep->rdllist) || ep->ovflist != EP_UNACTIVE_PTR; } /** |
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* ep_call_nested - Perform a bound (possibly) nested call, by checking * that the recursion limit is not exceeded, and that * the same nested call (by the meaning of same cookie) is * no re-entered. * * @ncalls: Pointer to the nested_calls structure to be used for this call. * @max_nests: Maximum number of allowed nesting calls. * @nproc: Nested call core function pointer. * @priv: Opaque data to be passed to the @nproc callback. * @cookie: Cookie to be used to identify this nested call. |
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* @ctx: This instance context. |
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* * Returns: Returns the code returned by the @nproc callback, or -1 if * the maximum recursion limit has been exceeded. |
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*/ |
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static int ep_call_nested(struct nested_calls *ncalls, int max_nests, int (*nproc)(void *, void *, int), void *priv, |
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void *cookie, void *ctx) |
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{ |
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int error, call_nests = 0; |
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unsigned long flags; |
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struct list_head *lsthead = &ncalls->tasks_call_list; struct nested_call_node *tncur; struct nested_call_node tnode; |
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|
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spin_lock_irqsave(&ncalls->lock, flags); |
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|
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/* * Try to see if the current task is already inside this wakeup call. * We use a list here, since the population inside this set is always * very much limited. */ |
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list_for_each_entry(tncur, lsthead, llink) { |
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if (tncur->ctx == ctx && |
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(tncur->cookie == cookie || ++call_nests > max_nests)) { |
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/* * Ops ... loop detected or maximum nest level reached. * We abort this wake by breaking the cycle itself. */ |
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error = -1; goto out_unlock; |
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} } |
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/* Add the current task and cookie to the list */ |
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tnode.ctx = ctx; |
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tnode.cookie = cookie; |
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list_add(&tnode.llink, lsthead); |
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spin_unlock_irqrestore(&ncalls->lock, flags); |
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|
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/* Call the nested function */ error = (*nproc)(priv, cookie, call_nests); |
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/* Remove the current task from the list */ |
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spin_lock_irqsave(&ncalls->lock, flags); |
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list_del(&tnode.llink); |
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out_unlock: |
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spin_unlock_irqrestore(&ncalls->lock, flags); return error; } |
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/* * As described in commit 0ccf831cb lockdep: annotate epoll * the use of wait queues used by epoll is done in a very controlled * manner. Wake ups can nest inside each other, but are never done * with the same locking. For example: * * dfd = socket(...); * efd1 = epoll_create(); * efd2 = epoll_create(); * epoll_ctl(efd1, EPOLL_CTL_ADD, dfd, ...); * epoll_ctl(efd2, EPOLL_CTL_ADD, efd1, ...); * * When a packet arrives to the device underneath "dfd", the net code will * issue a wake_up() on its poll wake list. Epoll (efd1) has installed a * callback wakeup entry on that queue, and the wake_up() performed by the * "dfd" net code will end up in ep_poll_callback(). At this point epoll * (efd1) notices that it may have some event ready, so it needs to wake up * the waiters on its poll wait list (efd2). So it calls ep_poll_safewake() * that ends up in another wake_up(), after having checked about the * recursion constraints. That are, no more than EP_MAX_POLLWAKE_NESTS, to * avoid stack blasting. * * When CONFIG_DEBUG_LOCK_ALLOC is enabled, make sure lockdep can handle * this special case of epoll. */ |
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#ifdef CONFIG_DEBUG_LOCK_ALLOC static inline void ep_wake_up_nested(wait_queue_head_t *wqueue, unsigned long events, int subclass) { unsigned long flags; spin_lock_irqsave_nested(&wqueue->lock, flags, subclass); wake_up_locked_poll(wqueue, events); spin_unlock_irqrestore(&wqueue->lock, flags); } #else static inline void ep_wake_up_nested(wait_queue_head_t *wqueue, unsigned long events, int subclass) { wake_up_poll(wqueue, events); } #endif |
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static int ep_poll_wakeup_proc(void *priv, void *cookie, int call_nests) { |
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ep_wake_up_nested((wait_queue_head_t *) cookie, POLLIN, 1 + call_nests); |
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return 0; } /* * Perform a safe wake up of the poll wait list. The problem is that * with the new callback'd wake up system, it is possible that the * poll callback is reentered from inside the call to wake_up() done * on the poll wait queue head. The rule is that we cannot reenter the * wake up code from the same task more than EP_MAX_NESTS times, * and we cannot reenter the same wait queue head at all. This will * enable to have a hierarchy of epoll file descriptor of no more than * EP_MAX_NESTS deep. */ static void ep_poll_safewake(wait_queue_head_t *wq) { |
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int this_cpu = get_cpu(); |
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ep_call_nested(&poll_safewake_ncalls, EP_MAX_NESTS, |
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ep_poll_wakeup_proc, NULL, wq, (void *) (long) this_cpu); put_cpu(); |
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} |
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static void ep_remove_wait_queue(struct eppoll_entry *pwq) { wait_queue_head_t *whead; rcu_read_lock(); /* If it is cleared by POLLFREE, it should be rcu-safe */ whead = rcu_dereference(pwq->whead); if (whead) remove_wait_queue(whead, &pwq->wait); rcu_read_unlock(); } |
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/* |
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* This function unregisters poll callbacks from the associated file * descriptor. Must be called with "mtx" held (or "epmutex" if called from * ep_free). |
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*/ |
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static void ep_unregister_pollwait(struct eventpoll *ep, struct epitem *epi) |
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{ |
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struct list_head *lsthead = &epi->pwqlist; struct eppoll_entry *pwq; |
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|
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while (!list_empty(lsthead)) { pwq = list_first_entry(lsthead, struct eppoll_entry, llink); |
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|
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list_del(&pwq->llink); |
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ep_remove_wait_queue(pwq); |
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kmem_cache_free(pwq_cache, pwq); |
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} |
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} |
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/* call only when ep->mtx is held */ static inline struct wakeup_source *ep_wakeup_source(struct epitem *epi) { return rcu_dereference_check(epi->ws, lockdep_is_held(&epi->ep->mtx)); } /* call only when ep->mtx is held */ static inline void ep_pm_stay_awake(struct epitem *epi) { struct wakeup_source *ws = ep_wakeup_source(epi); if (ws) __pm_stay_awake(ws); } static inline bool ep_has_wakeup_source(struct epitem *epi) { return rcu_access_pointer(epi->ws) ? true : false; } /* call when ep->mtx cannot be held (ep_poll_callback) */ static inline void ep_pm_stay_awake_rcu(struct epitem *epi) { struct wakeup_source *ws; rcu_read_lock(); ws = rcu_dereference(epi->ws); if (ws) __pm_stay_awake(ws); rcu_read_unlock(); } |
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/** * ep_scan_ready_list - Scans the ready list in a way that makes possible for * the scan code, to call f_op->poll(). Also allows for * O(NumReady) performance. * * @ep: Pointer to the epoll private data structure. * @sproc: Pointer to the scan callback. * @priv: Private opaque data passed to the @sproc callback. |
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* @depth: The current depth of recursive f_op->poll calls. |
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* * Returns: The same integer error code returned by the @sproc callback. */ static int ep_scan_ready_list(struct eventpoll *ep, int (*sproc)(struct eventpoll *, struct list_head *, void *), |
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void *priv, int depth) |
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{ int error, pwake = 0; unsigned long flags; struct epitem *epi, *nepi; |
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LIST_HEAD(txlist); |
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/* * We need to lock this because we could be hit by |
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* eventpoll_release_file() and epoll_ctl(). |
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*/ |
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mutex_lock_nested(&ep->mtx, depth); |
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/* * Steal the ready list, and re-init the original one to the * empty list. Also, set ep->ovflist to NULL so that events * happening while looping w/out locks, are not lost. We cannot * have the poll callback to queue directly on ep->rdllist, * because we want the "sproc" callback to be able to do it * in a lockless way. */ spin_lock_irqsave(&ep->lock, flags); |
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list_splice_init(&ep->rdllist, &txlist); |
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ep->ovflist = NULL; spin_unlock_irqrestore(&ep->lock, flags); /* * Now call the callback function. */ error = (*sproc)(ep, &txlist, priv); spin_lock_irqsave(&ep->lock, flags); /* * During the time we spent inside the "sproc" callback, some * other events might have been queued by the poll callback. * We re-insert them inside the main ready-list here. */ for (nepi = ep->ovflist; (epi = nepi) != NULL; nepi = epi->next, epi->next = EP_UNACTIVE_PTR) { /* * We need to check if the item is already in the list. * During the "sproc" callback execution time, items are * queued into ->ovflist but the "txlist" might already * contain them, and the list_splice() below takes care of them. */ |
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if (!ep_is_linked(&epi->rdllink)) { |
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list_add_tail(&epi->rdllink, &ep->rdllist); |
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ep_pm_stay_awake(epi); |
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} |
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} /* * We need to set back ep->ovflist to EP_UNACTIVE_PTR, so that after * releasing the lock, events will be queued in the normal way inside * ep->rdllist. */ ep->ovflist = EP_UNACTIVE_PTR; /* * Quickly re-inject items left on "txlist". */ list_splice(&txlist, &ep->rdllist); |
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__pm_relax(ep->ws); |
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if (!list_empty(&ep->rdllist)) { /* |
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* Wake up (if active) both the eventpoll wait list and * the ->poll() wait list (delayed after we release the lock). |
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*/ if (waitqueue_active(&ep->wq)) wake_up_locked(&ep->wq); if (waitqueue_active(&ep->poll_wait)) pwake++; } spin_unlock_irqrestore(&ep->lock, flags); mutex_unlock(&ep->mtx); /* We have to call this outside the lock */ if (pwake) ep_poll_safewake(&ep->poll_wait); return error; } |
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/* |
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* Removes a "struct epitem" from the eventpoll RB tree and deallocates |
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* all the associated resources. Must be called with "mtx" held. |
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*/ static int ep_remove(struct eventpoll *ep, struct epitem *epi) { |
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unsigned long flags; struct file *file = epi->ffd.file; |
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/* |
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* Removes poll wait queue hooks. We _have_ to do this without holding * the "ep->lock" otherwise a deadlock might occur. This because of the * sequence of the lock acquisition. Here we do "ep->lock" then the wait * queue head lock when unregistering the wait queue. The wakeup callback * will run by holding the wait queue head lock and will call our callback * that will try to get "ep->lock". |
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*/ |
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ep_unregister_pollwait(ep, epi); |
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|
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/* Remove the current item from the list of epoll hooks */ |
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spin_lock(&file->f_lock); |
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if (ep_is_linked(&epi->fllink)) list_del_init(&epi->fllink); |
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spin_unlock(&file->f_lock); |
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|
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rb_erase(&epi->rbn, &ep->rbr); |
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|
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spin_lock_irqsave(&ep->lock, flags); if (ep_is_linked(&epi->rdllink)) list_del_init(&epi->rdllink); spin_unlock_irqrestore(&ep->lock, flags); |
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|
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wakeup_source_unregister(ep_wakeup_source(epi)); |
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|
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/* At this point it is safe to free the eventpoll item */ |
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kmem_cache_free(epi_cache, epi); |
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|
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atomic_long_dec(&ep->user->epoll_watches); |
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|
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return 0; |
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} |
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static void ep_free(struct eventpoll *ep) |
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{ |
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struct rb_node *rbp; struct epitem *epi; |
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|
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/* We need to release all tasks waiting for these file */ if (waitqueue_active(&ep->poll_wait)) |
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ep_poll_safewake(&ep->poll_wait); |
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|
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/* * We need to lock this because we could be hit by * eventpoll_release_file() while we're freeing the "struct eventpoll". |
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* We do not need to hold "ep->mtx" here because the epoll file |
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* is on the way to be removed and no one has references to it * anymore. The only hit might come from eventpoll_release_file() but |
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* holding "epmutex" is sufficient here. |
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*/ mutex_lock(&epmutex); |
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/* |
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* Walks through the whole tree by unregistering poll callbacks. |
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*/ |
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for (rbp = rb_first(&ep->rbr); rbp; rbp = rb_next(rbp)) { epi = rb_entry(rbp, struct epitem, rbn); ep_unregister_pollwait(ep, epi); |
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cond_resched(); |
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} |
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/* |
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* Walks through the whole tree by freeing each "struct epitem". At this * point we are sure no poll callbacks will be lingering around, and also by |
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* holding "epmutex" we can be sure that no file cleanup code will hit |
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* us during this operation. So we can avoid the lock on "ep->lock". |
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* We do not need to lock ep->mtx, either, we only do it to prevent * a lockdep warning. |
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*/ |
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mutex_lock(&ep->mtx); |
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while ((rbp = rb_first(&ep->rbr)) != NULL) { |
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epi = rb_entry(rbp, struct epitem, rbn); ep_remove(ep, epi); |
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cond_resched(); |
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} |
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mutex_unlock(&ep->mtx); |
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|
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mutex_unlock(&epmutex); |
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mutex_destroy(&ep->mtx); |
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free_uid(ep->user); |
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wakeup_source_unregister(ep->ws); |
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kfree(ep); |
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} |
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|
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static int ep_eventpoll_release(struct inode *inode, struct file *file) { struct eventpoll *ep = file->private_data; |
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|
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if (ep) |
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ep_free(ep); |
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|
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return 0; |
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} |
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static inline unsigned int ep_item_poll(struct epitem *epi, poll_table *pt) { pt->_key = epi->event.events; return epi->ffd.file->f_op->poll(epi->ffd.file, pt) & epi->event.events; } |
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static int ep_read_events_proc(struct eventpoll *ep, struct list_head *head, void *priv) |
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{ struct epitem *epi, *tmp; |
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poll_table pt; |
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|
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init_poll_funcptr(&pt, NULL); |
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|
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list_for_each_entry_safe(epi, tmp, head, rdllink) { |
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if (ep_item_poll(epi, &pt)) |
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759 |
return POLLIN | POLLRDNORM; |
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else { |
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/* * Item has been dropped into the ready list by the poll * callback, but it's not actually ready, as far as * caller requested events goes. We can remove it here. */ |
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__pm_relax(ep_wakeup_source(epi)); |
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list_del_init(&epi->rdllink); |
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} |
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} return 0; } static int ep_poll_readyevents_proc(void *priv, void *cookie, int call_nests) { |
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return ep_scan_ready_list(priv, ep_read_events_proc, NULL, call_nests + 1); |
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} |
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static unsigned int ep_eventpoll_poll(struct file *file, poll_table *wait) { |
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int pollflags; |
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struct eventpoll *ep = file->private_data; |
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|
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/* Insert inside our poll wait queue */ poll_wait(file, &ep->poll_wait, wait); |
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/* * Proceed to find out if wanted events are really available inside * the ready list. This need to be done under ep_call_nested() * supervision, since the call to f_op->poll() done on listed files * could re-enter here. */ pollflags = ep_call_nested(&poll_readywalk_ncalls, EP_MAX_NESTS, |
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ep_poll_readyevents_proc, ep, ep, current); |
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|
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return pollflags != -1 ? pollflags : 0; |
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} |
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#ifdef CONFIG_PROC_FS static int ep_show_fdinfo(struct seq_file *m, struct file *f) { struct eventpoll *ep = f->private_data; struct rb_node *rbp; int ret = 0; mutex_lock(&ep->mtx); for (rbp = rb_first(&ep->rbr); rbp; rbp = rb_next(rbp)) { struct epitem *epi = rb_entry(rbp, struct epitem, rbn); ret = seq_printf(m, "tfd: %8d events: %8x data: %16llx ", epi->ffd.fd, epi->event.events, (long long)epi->event.data); if (ret) break; } mutex_unlock(&ep->mtx); return ret; } #endif |
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/* File callbacks that implement the eventpoll file behaviour */ static const struct file_operations eventpoll_fops = { |
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#ifdef CONFIG_PROC_FS .show_fdinfo = ep_show_fdinfo, #endif |
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.release = ep_eventpoll_release, |
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.poll = ep_eventpoll_poll, .llseek = noop_llseek, |
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}; |
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/* |
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* This is called from eventpoll_release() to unlink files from the eventpoll * interface. We need to have this facility to cleanup correctly files that are * closed without being removed from the eventpoll interface. |
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*/ |
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void eventpoll_release_file(struct file *file) |
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{ |
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struct list_head *lsthead = &file->f_ep_links; struct eventpoll *ep; struct epitem *epi; |
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/* |
684999149 Rename struct fil... |
840 |
* We don't want to get "file->f_lock" because it is not |
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841 |
* necessary. It is not necessary because we're in the "struct file" |
25985edce Fix common misspe... |
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* cleanup path, and this means that no one is using this file anymore. |
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* So, for example, epoll_ctl() cannot hit here since if we reach this |
67647d0fb epoll: fix some c... |
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* point, the file counter already went to zero and fget() would fail. |
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* The only hit might come from ep_free() but by holding the mutex |
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* will correctly serialize the operation. We do need to acquire |
d47de16c7 fix epoll single ... |
847 |
* "ep->mtx" after "epmutex" because ep_remove() requires it when called |
7699acd13 epoll cleanups: e... |
848 |
* from anywhere but ep_free(). |
684999149 Rename struct fil... |
849 850 |
* * Besides, ep_remove() acquires the lock, so we can't hold it here. |
b611967de [PATCH] epoll_pwa... |
851 |
*/ |
7699acd13 epoll cleanups: e... |
852 |
mutex_lock(&epmutex); |
b611967de [PATCH] epoll_pwa... |
853 |
|
7699acd13 epoll cleanups: e... |
854 855 |
while (!list_empty(lsthead)) { epi = list_first_entry(lsthead, struct epitem, fllink); |
b611967de [PATCH] epoll_pwa... |
856 |
|
7699acd13 epoll cleanups: e... |
857 858 |
ep = epi->ep; list_del_init(&epi->fllink); |
d8805e633 epoll: fix spurio... |
859 |
mutex_lock_nested(&ep->mtx, 0); |
7699acd13 epoll cleanups: e... |
860 |
ep_remove(ep, epi); |
d47de16c7 fix epoll single ... |
861 |
mutex_unlock(&ep->mtx); |
b611967de [PATCH] epoll_pwa... |
862 |
} |
7699acd13 epoll cleanups: e... |
863 |
mutex_unlock(&epmutex); |
b611967de [PATCH] epoll_pwa... |
864 |
} |
53d2be79d [PATCH] epoll: fi... |
865 |
static int ep_alloc(struct eventpoll **pep) |
1da177e4c Linux-2.6.12-rc2 |
866 |
{ |
7ef9964e6 epoll: introduce ... |
867 868 869 |
int error; struct user_struct *user; struct eventpoll *ep; |
1da177e4c Linux-2.6.12-rc2 |
870 |
|
7ef9964e6 epoll: introduce ... |
871 |
user = get_current_user(); |
7ef9964e6 epoll: introduce ... |
872 873 874 875 |
error = -ENOMEM; ep = kzalloc(sizeof(*ep), GFP_KERNEL); if (unlikely(!ep)) goto free_uid; |
1da177e4c Linux-2.6.12-rc2 |
876 |
|
c7ea76302 epoll locks chang... |
877 |
spin_lock_init(&ep->lock); |
d47de16c7 fix epoll single ... |
878 |
mutex_init(&ep->mtx); |
1da177e4c Linux-2.6.12-rc2 |
879 880 881 882 |
init_waitqueue_head(&ep->wq); init_waitqueue_head(&ep->poll_wait); INIT_LIST_HEAD(&ep->rdllist); ep->rbr = RB_ROOT; |
d47de16c7 fix epoll single ... |
883 |
ep->ovflist = EP_UNACTIVE_PTR; |
7ef9964e6 epoll: introduce ... |
884 |
ep->user = user; |
1da177e4c Linux-2.6.12-rc2 |
885 |
|
53d2be79d [PATCH] epoll: fi... |
886 |
*pep = ep; |
1da177e4c Linux-2.6.12-rc2 |
887 |
|
1da177e4c Linux-2.6.12-rc2 |
888 |
return 0; |
7ef9964e6 epoll: introduce ... |
889 890 891 892 |
free_uid: free_uid(user); return error; |
1da177e4c Linux-2.6.12-rc2 |
893 |
} |
1da177e4c Linux-2.6.12-rc2 |
894 |
/* |
c7ea76302 epoll locks chang... |
895 896 897 |
* Search the file inside the eventpoll tree. The RB tree operations * are protected by the "mtx" mutex, and ep_find() must be called with * "mtx" held. |
1da177e4c Linux-2.6.12-rc2 |
898 899 900 901 |
*/ static struct epitem *ep_find(struct eventpoll *ep, struct file *file, int fd) { int kcmp; |
1da177e4c Linux-2.6.12-rc2 |
902 903 904 |
struct rb_node *rbp; struct epitem *epi, *epir = NULL; struct epoll_filefd ffd; |
b030a4dd6 [PATCH] Remove ev... |
905 |
ep_set_ffd(&ffd, file, fd); |
1da177e4c Linux-2.6.12-rc2 |
906 907 |
for (rbp = ep->rbr.rb_node; rbp; ) { epi = rb_entry(rbp, struct epitem, rbn); |
b030a4dd6 [PATCH] Remove ev... |
908 |
kcmp = ep_cmp_ffd(&ffd, &epi->ffd); |
1da177e4c Linux-2.6.12-rc2 |
909 910 911 912 913 |
if (kcmp > 0) rbp = rbp->rb_right; else if (kcmp < 0) rbp = rbp->rb_left; else { |
1da177e4c Linux-2.6.12-rc2 |
914 915 916 917 |
epir = epi; break; } } |
1da177e4c Linux-2.6.12-rc2 |
918 |
|
1da177e4c Linux-2.6.12-rc2 |
919 920 |
return epir; } |
1da177e4c Linux-2.6.12-rc2 |
921 |
/* |
7699acd13 epoll cleanups: e... |
922 |
* This is the callback that is passed to the wait queue wakeup |
bf6a41db7 fs/eventpoll.c: f... |
923 |
* mechanism. It is called by the stored file descriptors when they |
7699acd13 epoll cleanups: e... |
924 |
* have events to report. |
1da177e4c Linux-2.6.12-rc2 |
925 |
*/ |
7699acd13 epoll cleanups: e... |
926 |
static int ep_poll_callback(wait_queue_t *wait, unsigned mode, int sync, void *key) |
1da177e4c Linux-2.6.12-rc2 |
927 |
{ |
7699acd13 epoll cleanups: e... |
928 929 930 931 |
int pwake = 0; unsigned long flags; struct epitem *epi = ep_item_from_wait(wait); struct eventpoll *ep = epi->ep; |
1da177e4c Linux-2.6.12-rc2 |
932 |
|
971316f05 epoll: ep_unregis... |
933 934 935 936 937 938 939 940 |
if ((unsigned long)key & POLLFREE) { ep_pwq_from_wait(wait)->whead = NULL; /* * whead = NULL above can race with ep_remove_wait_queue() * which can do another remove_wait_queue() after us, so we * can't use __remove_wait_queue(). whead->lock is held by * the caller. */ |
d80e731ec epoll: introduce ... |
941 |
list_del_init(&wait->task_list); |
971316f05 epoll: ep_unregis... |
942 |
} |
d80e731ec epoll: introduce ... |
943 |
|
c7ea76302 epoll locks chang... |
944 |
spin_lock_irqsave(&ep->lock, flags); |
1da177e4c Linux-2.6.12-rc2 |
945 |
|
7699acd13 epoll cleanups: e... |
946 947 948 949 950 951 952 |
/* * If the event mask does not contain any poll(2) event, we consider the * descriptor to be disabled. This condition is likely the effect of the * EPOLLONESHOT bit that disables the descriptor when an event is received, * until the next EPOLL_CTL_MOD will be issued. */ if (!(epi->event.events & ~EP_PRIVATE_BITS)) |
d47de16c7 fix epoll single ... |
953 954 955 |
goto out_unlock; /* |
2dfa4eeab epoll keyed wakeu... |
956 957 958 959 960 961 962 963 964 |
* Check the events coming with the callback. At this stage, not * every device reports the events in the "key" parameter of the * callback. We need to be able to handle both cases here, hence the * test for "key" != NULL before the event match test. */ if (key && !((unsigned long) key & epi->event.events)) goto out_unlock; /* |
bf6a41db7 fs/eventpoll.c: f... |
965 |
* If we are transferring events to userspace, we can hold no locks |
d47de16c7 fix epoll single ... |
966 |
* (because we're accessing user memory, and because of linux f_op->poll() |
bf6a41db7 fs/eventpoll.c: f... |
967 |
* semantics). All the events that happen during that period of time are |
d47de16c7 fix epoll single ... |
968 969 970 971 972 973 |
* chained in ep->ovflist and requeued later on. */ if (unlikely(ep->ovflist != EP_UNACTIVE_PTR)) { if (epi->next == EP_UNACTIVE_PTR) { epi->next = ep->ovflist; ep->ovflist = epi; |
4d7e30d98 epoll: Add a flag... |
974 975 976 977 978 979 980 |
if (epi->ws) { /* * Activate ep->ws since epi->ws may get * deactivated at any time. */ __pm_stay_awake(ep->ws); } |
d47de16c7 fix epoll single ... |
981 982 983 |
} goto out_unlock; } |
1da177e4c Linux-2.6.12-rc2 |
984 |
|
7699acd13 epoll cleanups: e... |
985 |
/* If this file is already in the ready list we exit soon */ |
4d7e30d98 epoll: Add a flag... |
986 |
if (!ep_is_linked(&epi->rdllink)) { |
5071f97ec epoll: fix epoll'... |
987 |
list_add_tail(&epi->rdllink, &ep->rdllist); |
eea1d5859 epoll: use RCU to... |
988 |
ep_pm_stay_awake_rcu(epi); |
4d7e30d98 epoll: Add a flag... |
989 |
} |
7699acd13 epoll cleanups: e... |
990 |
|
7699acd13 epoll cleanups: e... |
991 992 993 994 995 |
/* * Wake up ( if active ) both the eventpoll wait list and the ->poll() * wait list. */ if (waitqueue_active(&ep->wq)) |
4a6e9e2ce Use wake_up_locke... |
996 |
wake_up_locked(&ep->wq); |
7699acd13 epoll cleanups: e... |
997 998 |
if (waitqueue_active(&ep->poll_wait)) pwake++; |
d47de16c7 fix epoll single ... |
999 |
out_unlock: |
c7ea76302 epoll locks chang... |
1000 |
spin_unlock_irqrestore(&ep->lock, flags); |
1da177e4c Linux-2.6.12-rc2 |
1001 |
|
7699acd13 epoll cleanups: e... |
1002 1003 |
/* We have to call this outside the lock */ if (pwake) |
5071f97ec epoll: fix epoll'... |
1004 |
ep_poll_safewake(&ep->poll_wait); |
7699acd13 epoll cleanups: e... |
1005 1006 1007 |
return 1; } |
1da177e4c Linux-2.6.12-rc2 |
1008 1009 1010 1011 1012 1013 1014 1015 |
/* * This is the callback that is used to add our wait queue to the * target file wakeup lists. */ static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead, poll_table *pt) { |
b030a4dd6 [PATCH] Remove ev... |
1016 |
struct epitem *epi = ep_item_from_epqueue(pt); |
1da177e4c Linux-2.6.12-rc2 |
1017 |
struct eppoll_entry *pwq; |
e94b17660 [PATCH] slab: rem... |
1018 |
if (epi->nwait >= 0 && (pwq = kmem_cache_alloc(pwq_cache, GFP_KERNEL))) { |
1da177e4c Linux-2.6.12-rc2 |
1019 1020 1021 1022 1023 1024 |
init_waitqueue_func_entry(&pwq->wait, ep_poll_callback); pwq->whead = whead; pwq->base = epi; add_wait_queue(whead, &pwq->wait); list_add_tail(&pwq->llink, &epi->pwqlist); epi->nwait++; |
296e236e9 epoll: fix epoll'... |
1025 |
} else { |
1da177e4c Linux-2.6.12-rc2 |
1026 1027 |
/* We have to signal that an error occurred */ epi->nwait = -1; |
296e236e9 epoll: fix epoll'... |
1028 |
} |
1da177e4c Linux-2.6.12-rc2 |
1029 |
} |
1da177e4c Linux-2.6.12-rc2 |
1030 1031 1032 1033 1034 1035 1036 1037 1038 |
static void ep_rbtree_insert(struct eventpoll *ep, struct epitem *epi) { int kcmp; struct rb_node **p = &ep->rbr.rb_node, *parent = NULL; struct epitem *epic; while (*p) { parent = *p; epic = rb_entry(parent, struct epitem, rbn); |
b030a4dd6 [PATCH] Remove ev... |
1039 |
kcmp = ep_cmp_ffd(&epi->ffd, &epic->ffd); |
1da177e4c Linux-2.6.12-rc2 |
1040 1041 1042 1043 1044 1045 1046 1047 |
if (kcmp > 0) p = &parent->rb_right; else p = &parent->rb_left; } rb_link_node(&epi->rbn, parent, p); rb_insert_color(&epi->rbn, &ep->rbr); } |
a80a6b85b revert "epoll: su... |
1048 |
|
28d82dc1c epoll: limit paths |
1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 |
#define PATH_ARR_SIZE 5 /* * These are the number paths of length 1 to 5, that we are allowing to emanate * from a single file of interest. For example, we allow 1000 paths of length * 1, to emanate from each file of interest. This essentially represents the * potential wakeup paths, which need to be limited in order to avoid massive * uncontrolled wakeup storms. The common use case should be a single ep which * is connected to n file sources. In this case each file source has 1 path * of length 1. Thus, the numbers below should be more than sufficient. These * path limits are enforced during an EPOLL_CTL_ADD operation, since a modify * and delete can't add additional paths. Protected by the epmutex. */ static const int path_limits[PATH_ARR_SIZE] = { 1000, 500, 100, 50, 10 }; static int path_count[PATH_ARR_SIZE]; static int path_count_inc(int nests) { |
93dc6107a Don't limit non-n... |
1066 1067 1068 |
/* Allow an arbitrary number of depth 1 paths */ if (nests == 0) return 0; |
28d82dc1c epoll: limit paths |
1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 |
if (++path_count[nests] > path_limits[nests]) return -1; return 0; } static void path_count_init(void) { int i; for (i = 0; i < PATH_ARR_SIZE; i++) path_count[i] = 0; } static int reverse_path_check_proc(void *priv, void *cookie, int call_nests) { int error = 0; struct file *file = priv; struct file *child_file; struct epitem *epi; list_for_each_entry(epi, &file->f_ep_links, fllink) { child_file = epi->ep->file; if (is_file_epoll(child_file)) { if (list_empty(&child_file->f_ep_links)) { if (path_count_inc(call_nests)) { error = -1; break; } } else { error = ep_call_nested(&poll_loop_ncalls, EP_MAX_NESTS, reverse_path_check_proc, child_file, child_file, current); } if (error != 0) break; } else { printk(KERN_ERR "reverse_path_check_proc: " "file is not an ep! "); } } return error; } /** * reverse_path_check - The tfile_check_list is list of file *, which have * links that are proposed to be newly added. We need to * make sure that those added links don't add too many * paths such that we will spend all our time waking up * eventpoll objects. * * Returns: Returns zero if the proposed links don't create too many paths, * -1 otherwise. */ static int reverse_path_check(void) { |
28d82dc1c epoll: limit paths |
1127 1128 1129 1130 1131 |
int error = 0; struct file *current_file; /* let's call this for all tfiles */ list_for_each_entry(current_file, &tfile_check_list, f_tfile_llink) { |
28d82dc1c epoll: limit paths |
1132 1133 1134 1135 1136 1137 1138 1139 1140 |
path_count_init(); error = ep_call_nested(&poll_loop_ncalls, EP_MAX_NESTS, reverse_path_check_proc, current_file, current_file, current); if (error) break; } return error; } |
4d7e30d98 epoll: Add a flag... |
1141 1142 1143 |
static int ep_create_wakeup_source(struct epitem *epi) { const char *name; |
eea1d5859 epoll: use RCU to... |
1144 |
struct wakeup_source *ws; |
4d7e30d98 epoll: Add a flag... |
1145 1146 1147 1148 1149 1150 1151 1152 |
if (!epi->ep->ws) { epi->ep->ws = wakeup_source_register("eventpoll"); if (!epi->ep->ws) return -ENOMEM; } name = epi->ffd.file->f_path.dentry->d_name.name; |
eea1d5859 epoll: use RCU to... |
1153 1154 1155 |
ws = wakeup_source_register(name); if (!ws) |
4d7e30d98 epoll: Add a flag... |
1156 |
return -ENOMEM; |
eea1d5859 epoll: use RCU to... |
1157 |
rcu_assign_pointer(epi->ws, ws); |
4d7e30d98 epoll: Add a flag... |
1158 1159 1160 |
return 0; } |
eea1d5859 epoll: use RCU to... |
1161 1162 |
/* rare code path, only used when EPOLL_CTL_MOD removes a wakeup source */ static noinline void ep_destroy_wakeup_source(struct epitem *epi) |
4d7e30d98 epoll: Add a flag... |
1163 |
{ |
eea1d5859 epoll: use RCU to... |
1164 |
struct wakeup_source *ws = ep_wakeup_source(epi); |
d6d67e723 epoll: cleanup: u... |
1165 |
RCU_INIT_POINTER(epi->ws, NULL); |
eea1d5859 epoll: use RCU to... |
1166 1167 1168 1169 1170 1171 1172 1173 |
/* * wait for ep_pm_stay_awake_rcu to finish, synchronize_rcu is * used internally by wakeup_source_remove, too (called by * wakeup_source_unregister), so we cannot use call_rcu */ synchronize_rcu(); wakeup_source_unregister(ws); |
4d7e30d98 epoll: Add a flag... |
1174 |
} |
c7ea76302 epoll locks chang... |
1175 1176 1177 |
/* * Must be called with "mtx" held. */ |
1da177e4c Linux-2.6.12-rc2 |
1178 1179 1180 1181 1182 |
static int ep_insert(struct eventpoll *ep, struct epoll_event *event, struct file *tfile, int fd) { int error, revents, pwake = 0; unsigned long flags; |
52bd19f76 epoll: convert ma... |
1183 |
long user_watches; |
1da177e4c Linux-2.6.12-rc2 |
1184 1185 |
struct epitem *epi; struct ep_pqueue epq; |
52bd19f76 epoll: convert ma... |
1186 1187 |
user_watches = atomic_long_read(&ep->user->epoll_watches); if (unlikely(user_watches >= max_user_watches)) |
7ef9964e6 epoll: introduce ... |
1188 |
return -ENOSPC; |
e94b17660 [PATCH] slab: rem... |
1189 |
if (!(epi = kmem_cache_alloc(epi_cache, GFP_KERNEL))) |
7ef9964e6 epoll: introduce ... |
1190 |
return -ENOMEM; |
1da177e4c Linux-2.6.12-rc2 |
1191 1192 |
/* Item initialization follow here ... */ |
1da177e4c Linux-2.6.12-rc2 |
1193 1194 |
INIT_LIST_HEAD(&epi->rdllink); INIT_LIST_HEAD(&epi->fllink); |
1da177e4c Linux-2.6.12-rc2 |
1195 1196 |
INIT_LIST_HEAD(&epi->pwqlist); epi->ep = ep; |
b030a4dd6 [PATCH] Remove ev... |
1197 |
ep_set_ffd(&epi->ffd, tfile, fd); |
1da177e4c Linux-2.6.12-rc2 |
1198 |
epi->event = *event; |
1da177e4c Linux-2.6.12-rc2 |
1199 |
epi->nwait = 0; |
d47de16c7 fix epoll single ... |
1200 |
epi->next = EP_UNACTIVE_PTR; |
4d7e30d98 epoll: Add a flag... |
1201 1202 1203 1204 1205 |
if (epi->event.events & EPOLLWAKEUP) { error = ep_create_wakeup_source(epi); if (error) goto error_create_wakeup_source; } else { |
eea1d5859 epoll: use RCU to... |
1206 |
RCU_INIT_POINTER(epi->ws, NULL); |
4d7e30d98 epoll: Add a flag... |
1207 |
} |
1da177e4c Linux-2.6.12-rc2 |
1208 1209 1210 1211 1212 1213 1214 1215 |
/* Initialize the poll table using the queue callback */ epq.epi = epi; init_poll_funcptr(&epq.pt, ep_ptable_queue_proc); /* * Attach the item to the poll hooks and get current event bits. * We can safely use the file* here because its usage count has |
c7ea76302 epoll locks chang... |
1216 1217 1218 |
* been increased by the caller of this function. Note that after * this operation completes, the poll callback can start hitting * the new item. |
1da177e4c Linux-2.6.12-rc2 |
1219 |
*/ |
450d89ec0 epoll: cleanup: h... |
1220 |
revents = ep_item_poll(epi, &epq.pt); |
1da177e4c Linux-2.6.12-rc2 |
1221 1222 1223 1224 1225 1226 |
/* * We have to check if something went wrong during the poll wait queue * install process. Namely an allocation for a wait queue failed due * high memory pressure. */ |
7ef9964e6 epoll: introduce ... |
1227 |
error = -ENOMEM; |
1da177e4c Linux-2.6.12-rc2 |
1228 |
if (epi->nwait < 0) |
7699acd13 epoll cleanups: e... |
1229 |
goto error_unregister; |
1da177e4c Linux-2.6.12-rc2 |
1230 1231 |
/* Add the current item to the list of active epoll hook for this file */ |
684999149 Rename struct fil... |
1232 |
spin_lock(&tfile->f_lock); |
1da177e4c Linux-2.6.12-rc2 |
1233 |
list_add_tail(&epi->fllink, &tfile->f_ep_links); |
684999149 Rename struct fil... |
1234 |
spin_unlock(&tfile->f_lock); |
1da177e4c Linux-2.6.12-rc2 |
1235 |
|
c7ea76302 epoll locks chang... |
1236 1237 1238 1239 |
/* * Add the current item to the RB tree. All RB tree operations are * protected by "mtx", and ep_insert() is called with "mtx" held. */ |
1da177e4c Linux-2.6.12-rc2 |
1240 |
ep_rbtree_insert(ep, epi); |
28d82dc1c epoll: limit paths |
1241 1242 1243 1244 |
/* now check if we've created too many backpaths */ error = -EINVAL; if (reverse_path_check()) goto error_remove_epi; |
c7ea76302 epoll locks chang... |
1245 1246 |
/* We have to drop the new item inside our item list to keep track of it */ spin_lock_irqsave(&ep->lock, flags); |
1da177e4c Linux-2.6.12-rc2 |
1247 |
/* If the file is already "ready" we drop it inside the ready list */ |
b030a4dd6 [PATCH] Remove ev... |
1248 |
if ((revents & event->events) && !ep_is_linked(&epi->rdllink)) { |
1da177e4c Linux-2.6.12-rc2 |
1249 |
list_add_tail(&epi->rdllink, &ep->rdllist); |
eea1d5859 epoll: use RCU to... |
1250 |
ep_pm_stay_awake(epi); |
1da177e4c Linux-2.6.12-rc2 |
1251 1252 1253 |
/* Notify waiting tasks that events are available */ if (waitqueue_active(&ep->wq)) |
4a6e9e2ce Use wake_up_locke... |
1254 |
wake_up_locked(&ep->wq); |
1da177e4c Linux-2.6.12-rc2 |
1255 1256 1257 |
if (waitqueue_active(&ep->poll_wait)) pwake++; } |
c7ea76302 epoll locks chang... |
1258 |
spin_unlock_irqrestore(&ep->lock, flags); |
1da177e4c Linux-2.6.12-rc2 |
1259 |
|
52bd19f76 epoll: convert ma... |
1260 |
atomic_long_inc(&ep->user->epoll_watches); |
7ef9964e6 epoll: introduce ... |
1261 |
|
1da177e4c Linux-2.6.12-rc2 |
1262 1263 |
/* We have to call this outside the lock */ if (pwake) |
5071f97ec epoll: fix epoll'... |
1264 |
ep_poll_safewake(&ep->poll_wait); |
1da177e4c Linux-2.6.12-rc2 |
1265 |
|
1da177e4c Linux-2.6.12-rc2 |
1266 |
return 0; |
28d82dc1c epoll: limit paths |
1267 1268 1269 1270 1271 1272 1273 |
error_remove_epi: spin_lock(&tfile->f_lock); if (ep_is_linked(&epi->fllink)) list_del_init(&epi->fllink); spin_unlock(&tfile->f_lock); rb_erase(&epi->rbn, &ep->rbr); |
7699acd13 epoll cleanups: e... |
1274 |
error_unregister: |
1da177e4c Linux-2.6.12-rc2 |
1275 1276 1277 1278 |
ep_unregister_pollwait(ep, epi); /* * We need to do this because an event could have been arrived on some |
67647d0fb epoll: fix some c... |
1279 1280 1281 |
* allocated wait queue. Note that we don't care about the ep->ovflist * list, since that is used/cleaned only inside a section bound by "mtx". * And ep_insert() is called with "mtx" held. |
1da177e4c Linux-2.6.12-rc2 |
1282 |
*/ |
c7ea76302 epoll locks chang... |
1283 |
spin_lock_irqsave(&ep->lock, flags); |
b030a4dd6 [PATCH] Remove ev... |
1284 |
if (ep_is_linked(&epi->rdllink)) |
6192bd536 epoll: optimizati... |
1285 |
list_del_init(&epi->rdllink); |
c7ea76302 epoll locks chang... |
1286 |
spin_unlock_irqrestore(&ep->lock, flags); |
1da177e4c Linux-2.6.12-rc2 |
1287 |
|
eea1d5859 epoll: use RCU to... |
1288 |
wakeup_source_unregister(ep_wakeup_source(epi)); |
4d7e30d98 epoll: Add a flag... |
1289 1290 |
error_create_wakeup_source: |
b030a4dd6 [PATCH] Remove ev... |
1291 |
kmem_cache_free(epi_cache, epi); |
7ef9964e6 epoll: introduce ... |
1292 |
|
1da177e4c Linux-2.6.12-rc2 |
1293 1294 |
return error; } |
1da177e4c Linux-2.6.12-rc2 |
1295 1296 |
/* * Modify the interest event mask by dropping an event if the new mask |
c7ea76302 epoll locks chang... |
1297 |
* has a match in the current file status. Must be called with "mtx" held. |
1da177e4c Linux-2.6.12-rc2 |
1298 1299 1300 1301 1302 |
*/ static int ep_modify(struct eventpoll *ep, struct epitem *epi, struct epoll_event *event) { int pwake = 0; unsigned int revents; |
626cf2366 poll: add poll_re... |
1303 1304 1305 |
poll_table pt; init_poll_funcptr(&pt, NULL); |
1da177e4c Linux-2.6.12-rc2 |
1306 1307 |
/* |
e057e15ff epoll: clean up e... |
1308 1309 1310 |
* Set the new event interest mask before calling f_op->poll(); * otherwise we might miss an event that happens between the * f_op->poll() call and the new event set registering. |
1da177e4c Linux-2.6.12-rc2 |
1311 |
*/ |
128dd1759 epoll: prevent mi... |
1312 |
epi->event.events = event->events; /* need barrier below */ |
e057e15ff epoll: clean up e... |
1313 |
epi->event.data = event->data; /* protected by mtx */ |
4d7e30d98 epoll: Add a flag... |
1314 |
if (epi->event.events & EPOLLWAKEUP) { |
eea1d5859 epoll: use RCU to... |
1315 |
if (!ep_has_wakeup_source(epi)) |
4d7e30d98 epoll: Add a flag... |
1316 |
ep_create_wakeup_source(epi); |
eea1d5859 epoll: use RCU to... |
1317 |
} else if (ep_has_wakeup_source(epi)) { |
4d7e30d98 epoll: Add a flag... |
1318 1319 |
ep_destroy_wakeup_source(epi); } |
1da177e4c Linux-2.6.12-rc2 |
1320 1321 |
/* |
128dd1759 epoll: prevent mi... |
1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 |
* The following barrier has two effects: * * 1) Flush epi changes above to other CPUs. This ensures * we do not miss events from ep_poll_callback if an * event occurs immediately after we call f_op->poll(). * We need this because we did not take ep->lock while * changing epi above (but ep_poll_callback does take * ep->lock). * * 2) We also need to ensure we do not miss _past_ events * when calling f_op->poll(). This barrier also * pairs with the barrier in wq_has_sleeper (see * comments for wq_has_sleeper). * * This barrier will now guarantee ep_poll_callback or f_op->poll * (or both) will notice the readiness of an item. */ smp_mb(); /* |
1da177e4c Linux-2.6.12-rc2 |
1342 1343 1344 |
* Get current event bits. We can safely use the file* here because * its usage count has been increased by the caller of this function. */ |
450d89ec0 epoll: cleanup: h... |
1345 |
revents = ep_item_poll(epi, &pt); |
1da177e4c Linux-2.6.12-rc2 |
1346 |
|
1da177e4c Linux-2.6.12-rc2 |
1347 |
/* |
c7ea76302 epoll locks chang... |
1348 |
* If the item is "hot" and it is not registered inside the ready |
67647d0fb epoll: fix some c... |
1349 |
* list, push it inside. |
1da177e4c Linux-2.6.12-rc2 |
1350 |
*/ |
c7ea76302 epoll locks chang... |
1351 |
if (revents & event->events) { |
e057e15ff epoll: clean up e... |
1352 |
spin_lock_irq(&ep->lock); |
c7ea76302 epoll locks chang... |
1353 1354 |
if (!ep_is_linked(&epi->rdllink)) { list_add_tail(&epi->rdllink, &ep->rdllist); |
eea1d5859 epoll: use RCU to... |
1355 |
ep_pm_stay_awake(epi); |
c7ea76302 epoll locks chang... |
1356 1357 1358 |
/* Notify waiting tasks that events are available */ if (waitqueue_active(&ep->wq)) |
4a6e9e2ce Use wake_up_locke... |
1359 |
wake_up_locked(&ep->wq); |
c7ea76302 epoll locks chang... |
1360 1361 |
if (waitqueue_active(&ep->poll_wait)) pwake++; |
7699acd13 epoll cleanups: e... |
1362 |
} |
e057e15ff epoll: clean up e... |
1363 |
spin_unlock_irq(&ep->lock); |
7699acd13 epoll cleanups: e... |
1364 |
} |
1da177e4c Linux-2.6.12-rc2 |
1365 |
|
7699acd13 epoll cleanups: e... |
1366 1367 |
/* We have to call this outside the lock */ if (pwake) |
5071f97ec epoll: fix epoll'... |
1368 |
ep_poll_safewake(&ep->poll_wait); |
1da177e4c Linux-2.6.12-rc2 |
1369 |
|
7699acd13 epoll cleanups: e... |
1370 |
return 0; |
1da177e4c Linux-2.6.12-rc2 |
1371 |
} |
296e236e9 epoll: fix epoll'... |
1372 1373 |
static int ep_send_events_proc(struct eventpoll *ep, struct list_head *head, void *priv) |
1da177e4c Linux-2.6.12-rc2 |
1374 |
{ |
5071f97ec epoll: fix epoll'... |
1375 1376 |
struct ep_send_events_data *esed = priv; int eventcnt; |
296e236e9 epoll: fix epoll'... |
1377 |
unsigned int revents; |
5071f97ec epoll: fix epoll'... |
1378 1379 |
struct epitem *epi; struct epoll_event __user *uevent; |
eea1d5859 epoll: use RCU to... |
1380 |
struct wakeup_source *ws; |
626cf2366 poll: add poll_re... |
1381 1382 1383 |
poll_table pt; init_poll_funcptr(&pt, NULL); |
1da177e4c Linux-2.6.12-rc2 |
1384 |
|
296e236e9 epoll: fix epoll'... |
1385 |
/* |
5071f97ec epoll: fix epoll'... |
1386 1387 1388 |
* We can loop without lock because we are passed a task private list. * Items cannot vanish during the loop because ep_scan_ready_list() is * holding "mtx" during this call. |
296e236e9 epoll: fix epoll'... |
1389 |
*/ |
5071f97ec epoll: fix epoll'... |
1390 1391 1392 |
for (eventcnt = 0, uevent = esed->events; !list_empty(head) && eventcnt < esed->maxevents;) { epi = list_first_entry(head, struct epitem, rdllink); |
d47de16c7 fix epoll single ... |
1393 |
|
4d7e30d98 epoll: Add a flag... |
1394 1395 1396 1397 1398 1399 1400 1401 1402 |
/* * Activate ep->ws before deactivating epi->ws to prevent * triggering auto-suspend here (in case we reactive epi->ws * below). * * This could be rearranged to delay the deactivation of epi->ws * instead, but then epi->ws would temporarily be out of sync * with ep_is_linked(). */ |
eea1d5859 epoll: use RCU to... |
1403 1404 1405 1406 1407 1408 |
ws = ep_wakeup_source(epi); if (ws) { if (ws->active) __pm_stay_awake(ep->ws); __pm_relax(ws); } |
d47de16c7 fix epoll single ... |
1409 |
list_del_init(&epi->rdllink); |
1da177e4c Linux-2.6.12-rc2 |
1410 |
|
450d89ec0 epoll: cleanup: h... |
1411 |
revents = ep_item_poll(epi, &pt); |
5071f97ec epoll: fix epoll'... |
1412 |
|
296e236e9 epoll: fix epoll'... |
1413 |
/* |
5071f97ec epoll: fix epoll'... |
1414 1415 1416 1417 |
* If the event mask intersect the caller-requested one, * deliver the event to userspace. Again, ep_scan_ready_list() * is holding "mtx", so no operations coming from userspace * can change the item. |
296e236e9 epoll: fix epoll'... |
1418 1419 |
*/ if (revents) { |
5071f97ec epoll: fix epoll'... |
1420 |
if (__put_user(revents, &uevent->events) || |
d03058828 epoll: remember t... |
1421 1422 |
__put_user(epi->event.data, &uevent->data)) { list_add(&epi->rdllink, head); |
eea1d5859 epoll: use RCU to... |
1423 |
ep_pm_stay_awake(epi); |
296e236e9 epoll: fix epoll'... |
1424 |
return eventcnt ? eventcnt : -EFAULT; |
d03058828 epoll: remember t... |
1425 |
} |
296e236e9 epoll: fix epoll'... |
1426 |
eventcnt++; |
5071f97ec epoll: fix epoll'... |
1427 |
uevent++; |
296e236e9 epoll: fix epoll'... |
1428 1429 1430 1431 1432 1433 1434 1435 |
if (epi->event.events & EPOLLONESHOT) epi->event.events &= EP_PRIVATE_BITS; else if (!(epi->event.events & EPOLLET)) { /* * If this file has been added with Level * Trigger mode, we need to insert back inside * the ready list, so that the next call to * epoll_wait() will check again the events |
25985edce Fix common misspe... |
1436 |
* availability. At this point, no one can insert |
296e236e9 epoll: fix epoll'... |
1437 1438 1439 1440 1441 1442 |
* into ep->rdllist besides us. The epoll_ctl() * callers are locked out by * ep_scan_ready_list() holding "mtx" and the * poll callback will queue them in ep->ovflist. */ list_add_tail(&epi->rdllink, &ep->rdllist); |
eea1d5859 epoll: use RCU to... |
1443 |
ep_pm_stay_awake(epi); |
296e236e9 epoll: fix epoll'... |
1444 1445 1446 |
} } } |
5071f97ec epoll: fix epoll'... |
1447 1448 1449 |
return eventcnt; } |
d47de16c7 fix epoll single ... |
1450 |
|
296e236e9 epoll: fix epoll'... |
1451 1452 |
static int ep_send_events(struct eventpoll *ep, struct epoll_event __user *events, int maxevents) |
5071f97ec epoll: fix epoll'... |
1453 1454 |
{ struct ep_send_events_data esed; |
1da177e4c Linux-2.6.12-rc2 |
1455 |
|
5071f97ec epoll: fix epoll'... |
1456 1457 |
esed.maxevents = maxevents; esed.events = events; |
6192bd536 epoll: optimizati... |
1458 |
|
d8805e633 epoll: fix spurio... |
1459 |
return ep_scan_ready_list(ep, ep_send_events_proc, &esed, 0); |
1da177e4c Linux-2.6.12-rc2 |
1460 |
} |
0781b909b epoll: epoll_wait... |
1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 |
static inline struct timespec ep_set_mstimeout(long ms) { struct timespec now, ts = { .tv_sec = ms / MSEC_PER_SEC, .tv_nsec = NSEC_PER_MSEC * (ms % MSEC_PER_SEC), }; ktime_get_ts(&now); return timespec_add_safe(now, ts); } |
f4d93ad74 epoll: fix compil... |
1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 |
/** * ep_poll - Retrieves ready events, and delivers them to the caller supplied * event buffer. * * @ep: Pointer to the eventpoll context. * @events: Pointer to the userspace buffer where the ready events should be * stored. * @maxevents: Size (in terms of number of events) of the caller event buffer. * @timeout: Maximum timeout for the ready events fetch operation, in * milliseconds. If the @timeout is zero, the function will not block, * while if the @timeout is less than zero, the function will block * until at least one event has been retrieved (or an error * occurred). * * Returns: Returns the number of ready events which have been fetched, or an * error code, in case of error. */ |
1da177e4c Linux-2.6.12-rc2 |
1488 1489 1490 |
static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events, int maxevents, long timeout) { |
f4d93ad74 epoll: fix compil... |
1491 |
int res = 0, eavail, timed_out = 0; |
1da177e4c Linux-2.6.12-rc2 |
1492 |
unsigned long flags; |
f4d93ad74 epoll: fix compil... |
1493 |
long slack = 0; |
1da177e4c Linux-2.6.12-rc2 |
1494 |
wait_queue_t wait; |
95aac7b1c epoll: make epoll... |
1495 1496 1497 |
ktime_t expires, *to = NULL; if (timeout > 0) { |
0781b909b epoll: epoll_wait... |
1498 |
struct timespec end_time = ep_set_mstimeout(timeout); |
95aac7b1c epoll: make epoll... |
1499 1500 1501 1502 |
slack = select_estimate_accuracy(&end_time); to = &expires; *to = timespec_to_ktime(end_time); } else if (timeout == 0) { |
f4d93ad74 epoll: fix compil... |
1503 1504 1505 1506 |
/* * Avoid the unnecessary trip to the wait queue loop, if the * caller specified a non blocking operation. */ |
95aac7b1c epoll: make epoll... |
1507 |
timed_out = 1; |
f4d93ad74 epoll: fix compil... |
1508 1509 |
spin_lock_irqsave(&ep->lock, flags); goto check_events; |
95aac7b1c epoll: make epoll... |
1510 |
} |
1da177e4c Linux-2.6.12-rc2 |
1511 |
|
f4d93ad74 epoll: fix compil... |
1512 |
fetch_events: |
c7ea76302 epoll locks chang... |
1513 |
spin_lock_irqsave(&ep->lock, flags); |
1da177e4c Linux-2.6.12-rc2 |
1514 |
|
3fb0e584a epoll: move ready... |
1515 |
if (!ep_events_available(ep)) { |
1da177e4c Linux-2.6.12-rc2 |
1516 1517 1518 1519 1520 1521 |
/* * We don't have any available event to return to the caller. * We need to sleep here, and we will be wake up by * ep_poll_callback() when events will become available. */ init_waitqueue_entry(&wait, current); |
a93d2f174 sched, wait: Use ... |
1522 |
__add_wait_queue_exclusive(&ep->wq, &wait); |
1da177e4c Linux-2.6.12-rc2 |
1523 1524 1525 1526 1527 1528 1529 1530 |
for (;;) { /* * We don't want to sleep if the ep_poll_callback() sends us * a wakeup in between. That's why we set the task state * to TASK_INTERRUPTIBLE before doing the checks. */ set_current_state(TASK_INTERRUPTIBLE); |
3fb0e584a epoll: move ready... |
1531 |
if (ep_events_available(ep) || timed_out) |
1da177e4c Linux-2.6.12-rc2 |
1532 1533 1534 1535 1536 |
break; if (signal_pending(current)) { res = -EINTR; break; } |
c7ea76302 epoll locks chang... |
1537 |
spin_unlock_irqrestore(&ep->lock, flags); |
1c441e921 epoll: use freeza... |
1538 1539 |
if (!freezable_schedule_hrtimeout_range(to, slack, HRTIMER_MODE_ABS)) |
95aac7b1c epoll: make epoll... |
1540 |
timed_out = 1; |
c7ea76302 epoll locks chang... |
1541 |
spin_lock_irqsave(&ep->lock, flags); |
1da177e4c Linux-2.6.12-rc2 |
1542 |
} |
3419b23a9 [PATCH] epoll: us... |
1543 |
__remove_wait_queue(&ep->wq, &wait); |
1da177e4c Linux-2.6.12-rc2 |
1544 1545 1546 |
set_current_state(TASK_RUNNING); } |
f4d93ad74 epoll: fix compil... |
1547 |
check_events: |
1da177e4c Linux-2.6.12-rc2 |
1548 |
/* Is it worth to try to dig for events ? */ |
3fb0e584a epoll: move ready... |
1549 |
eavail = ep_events_available(ep); |
1da177e4c Linux-2.6.12-rc2 |
1550 |
|
c7ea76302 epoll locks chang... |
1551 |
spin_unlock_irqrestore(&ep->lock, flags); |
1da177e4c Linux-2.6.12-rc2 |
1552 1553 1554 1555 1556 1557 1558 |
/* * Try to transfer events to user space. In case we get 0 events and * there's still timeout left over, we go trying again in search of * more luck. */ if (!res && eavail && |
95aac7b1c epoll: make epoll... |
1559 |
!(res = ep_send_events(ep, events, maxevents)) && !timed_out) |
f4d93ad74 epoll: fix compil... |
1560 |
goto fetch_events; |
1da177e4c Linux-2.6.12-rc2 |
1561 1562 1563 |
return res; } |
22bacca48 epoll: prevent cr... |
1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 |
/** * ep_loop_check_proc - Callback function to be passed to the @ep_call_nested() * API, to verify that adding an epoll file inside another * epoll structure, does not violate the constraints, in * terms of closed loops, or too deep chains (which can * result in excessive stack usage). * * @priv: Pointer to the epoll file to be currently checked. * @cookie: Original cookie for this call. This is the top-of-the-chain epoll * data structure pointer. * @call_nests: Current dept of the @ep_call_nested() call stack. * * Returns: Returns zero if adding the epoll @file inside current epoll * structure @ep does not violate the constraints, or -1 otherwise. */ static int ep_loop_check_proc(void *priv, void *cookie, int call_nests) { int error = 0; struct file *file = priv; struct eventpoll *ep = file->private_data; |
28d82dc1c epoll: limit paths |
1584 |
struct eventpoll *ep_tovisit; |
22bacca48 epoll: prevent cr... |
1585 1586 |
struct rb_node *rbp; struct epitem *epi; |
d8805e633 epoll: fix spurio... |
1587 |
mutex_lock_nested(&ep->mtx, call_nests + 1); |
28d82dc1c epoll: limit paths |
1588 1589 |
ep->visited = 1; list_add(&ep->visited_list_link, &visited_list); |
22bacca48 epoll: prevent cr... |
1590 1591 1592 |
for (rbp = rb_first(&ep->rbr); rbp; rbp = rb_next(rbp)) { epi = rb_entry(rbp, struct epitem, rbn); if (unlikely(is_file_epoll(epi->ffd.file))) { |
28d82dc1c epoll: limit paths |
1593 1594 1595 |
ep_tovisit = epi->ffd.file->private_data; if (ep_tovisit->visited) continue; |
22bacca48 epoll: prevent cr... |
1596 |
error = ep_call_nested(&poll_loop_ncalls, EP_MAX_NESTS, |
28d82dc1c epoll: limit paths |
1597 1598 |
ep_loop_check_proc, epi->ffd.file, ep_tovisit, current); |
22bacca48 epoll: prevent cr... |
1599 1600 |
if (error != 0) break; |
28d82dc1c epoll: limit paths |
1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 |
} else { /* * If we've reached a file that is not associated with * an ep, then we need to check if the newly added * links are going to add too many wakeup paths. We do * this by adding it to the tfile_check_list, if it's * not already there, and calling reverse_path_check() * during ep_insert(). */ if (list_empty(&epi->ffd.file->f_tfile_llink)) list_add(&epi->ffd.file->f_tfile_llink, &tfile_check_list); |
22bacca48 epoll: prevent cr... |
1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 |
} } mutex_unlock(&ep->mtx); return error; } /** * ep_loop_check - Performs a check to verify that adding an epoll file (@file) * another epoll file (represented by @ep) does not create * closed loops or too deep chains. * * @ep: Pointer to the epoll private data structure. * @file: Pointer to the epoll file to be checked. * * Returns: Returns zero if adding the epoll @file inside current epoll * structure @ep does not violate the constraints, or -1 otherwise. */ static int ep_loop_check(struct eventpoll *ep, struct file *file) { |
28d82dc1c epoll: limit paths |
1633 1634 1635 1636 |
int ret; struct eventpoll *ep_cur, *ep_next; ret = ep_call_nested(&poll_loop_ncalls, EP_MAX_NESTS, |
22bacca48 epoll: prevent cr... |
1637 |
ep_loop_check_proc, file, ep, current); |
28d82dc1c epoll: limit paths |
1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 |
/* clear visited list */ list_for_each_entry_safe(ep_cur, ep_next, &visited_list, visited_list_link) { ep_cur->visited = 0; list_del(&ep_cur->visited_list_link); } return ret; } static void clear_tfile_check_list(void) { struct file *file; /* first clear the tfile_check_list */ while (!list_empty(&tfile_check_list)) { file = list_first_entry(&tfile_check_list, struct file, f_tfile_llink); list_del_init(&file->f_tfile_llink); } INIT_LIST_HEAD(&tfile_check_list); |
22bacca48 epoll: prevent cr... |
1658 |
} |
7699acd13 epoll cleanups: e... |
1659 |
/* |
523723bb5 fs/eventpoll.c: f... |
1660 |
* Open an eventpoll file descriptor. |
7699acd13 epoll cleanups: e... |
1661 |
*/ |
5a8a82b1d [CVE-2009-0029] S... |
1662 |
SYSCALL_DEFINE1(epoll_create1, int, flags) |
7699acd13 epoll cleanups: e... |
1663 |
{ |
28d82dc1c epoll: limit paths |
1664 |
int error, fd; |
bb57c3edc epoll: remove deb... |
1665 |
struct eventpoll *ep = NULL; |
28d82dc1c epoll: limit paths |
1666 |
struct file *file; |
7699acd13 epoll cleanups: e... |
1667 |
|
e38b36f32 flag parameters: ... |
1668 1669 |
/* Check the EPOLL_* constant for consistency. */ BUILD_BUG_ON(EPOLL_CLOEXEC != O_CLOEXEC); |
296e236e9 epoll: fix epoll'... |
1670 1671 |
if (flags & ~EPOLL_CLOEXEC) return -EINVAL; |
7699acd13 epoll cleanups: e... |
1672 |
/* |
bb57c3edc epoll: remove deb... |
1673 |
* Create the internal data structure ("struct eventpoll"). |
7699acd13 epoll cleanups: e... |
1674 |
*/ |
9fe5ad9c8 flag parameters a... |
1675 |
error = ep_alloc(&ep); |
bb57c3edc epoll: remove deb... |
1676 1677 |
if (error < 0) return error; |
7699acd13 epoll cleanups: e... |
1678 1679 |
/* * Creates all the items needed to setup an eventpoll file. That is, |
2030a42ce [PATCH] sanitize ... |
1680 |
* a file structure and a free file descriptor. |
7699acd13 epoll cleanups: e... |
1681 |
*/ |
28d82dc1c epoll: limit paths |
1682 1683 1684 1685 1686 1687 |
fd = get_unused_fd_flags(O_RDWR | (flags & O_CLOEXEC)); if (fd < 0) { error = fd; goto out_free_ep; } file = anon_inode_getfile("[eventpoll]", &eventpoll_fops, ep, |
628ff7c1d anonfd: Allow mak... |
1688 |
O_RDWR | (flags & O_CLOEXEC)); |
28d82dc1c epoll: limit paths |
1689 1690 1691 1692 |
if (IS_ERR(file)) { error = PTR_ERR(file); goto out_free_fd; } |
28d82dc1c epoll: limit paths |
1693 |
ep->file = file; |
98022748f eventpoll: use-af... |
1694 |
fd_install(fd, file); |
28d82dc1c epoll: limit paths |
1695 1696 1697 1698 1699 1700 |
return fd; out_free_fd: put_unused_fd(fd); out_free_ep: ep_free(ep); |
bb57c3edc epoll: remove deb... |
1701 |
return error; |
7699acd13 epoll cleanups: e... |
1702 |
} |
5a8a82b1d [CVE-2009-0029] S... |
1703 |
SYSCALL_DEFINE1(epoll_create, int, size) |
a0998b50c flag parameters: ... |
1704 |
{ |
bfe3891a5 epoll: fix size c... |
1705 |
if (size <= 0) |
9fe5ad9c8 flag parameters a... |
1706 1707 1708 |
return -EINVAL; return sys_epoll_create1(0); |
a0998b50c flag parameters: ... |
1709 |
} |
7699acd13 epoll cleanups: e... |
1710 1711 1712 |
/* * The following function implements the controller interface for * the eventpoll file that enables the insertion/removal/change of |
67647d0fb epoll: fix some c... |
1713 |
* file descriptors inside the interest set. |
7699acd13 epoll cleanups: e... |
1714 |
*/ |
5a8a82b1d [CVE-2009-0029] S... |
1715 1716 |
SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd, struct epoll_event __user *, event) |
7699acd13 epoll cleanups: e... |
1717 1718 |
{ int error; |
22bacca48 epoll: prevent cr... |
1719 |
int did_lock_epmutex = 0; |
7e3fb5842 switch epoll_ctl(... |
1720 |
struct fd f, tf; |
7699acd13 epoll cleanups: e... |
1721 1722 1723 |
struct eventpoll *ep; struct epitem *epi; struct epoll_event epds; |
7699acd13 epoll cleanups: e... |
1724 1725 1726 1727 |
error = -EFAULT; if (ep_op_has_event(op) && copy_from_user(&epds, event, sizeof(struct epoll_event))) goto error_return; |
7699acd13 epoll cleanups: e... |
1728 |
error = -EBADF; |
7e3fb5842 switch epoll_ctl(... |
1729 1730 |
f = fdget(epfd); if (!f.file) |
7699acd13 epoll cleanups: e... |
1731 1732 1733 |
goto error_return; /* Get the "struct file *" for the target file */ |
7e3fb5842 switch epoll_ctl(... |
1734 1735 |
tf = fdget(fd); if (!tf.file) |
7699acd13 epoll cleanups: e... |
1736 1737 1738 1739 |
goto error_fput; /* The target file descriptor must support poll */ error = -EPERM; |
7e3fb5842 switch epoll_ctl(... |
1740 |
if (!tf.file->f_op || !tf.file->f_op->poll) |
7699acd13 epoll cleanups: e... |
1741 |
goto error_tgt_fput; |
4d7e30d98 epoll: Add a flag... |
1742 |
/* Check if EPOLLWAKEUP is allowed */ |
d9914cf66 PM: Rename CAP_EP... |
1743 |
if ((epds.events & EPOLLWAKEUP) && !capable(CAP_BLOCK_SUSPEND)) |
a8159414d epoll: Fix user s... |
1744 |
epds.events &= ~EPOLLWAKEUP; |
4d7e30d98 epoll: Add a flag... |
1745 |
|
7699acd13 epoll cleanups: e... |
1746 1747 1748 1749 1750 1751 |
/* * We have to check that the file structure underneath the file descriptor * the user passed to us _is_ an eventpoll file. And also we do not permit * adding an epoll file descriptor inside itself. */ error = -EINVAL; |
7e3fb5842 switch epoll_ctl(... |
1752 |
if (f.file == tf.file || !is_file_epoll(f.file)) |
7699acd13 epoll cleanups: e... |
1753 1754 1755 1756 1757 1758 |
goto error_tgt_fput; /* * At this point it is safe to assume that the "private_data" contains * our own data structure. */ |
7e3fb5842 switch epoll_ctl(... |
1759 |
ep = f.file->private_data; |
7699acd13 epoll cleanups: e... |
1760 |
|
22bacca48 epoll: prevent cr... |
1761 1762 1763 |
/* * When we insert an epoll file descriptor, inside another epoll file * descriptor, there is the change of creating closed loops, which are |
28d82dc1c epoll: limit paths |
1764 1765 1766 1767 |
* better be handled here, than in more critical paths. While we are * checking for loops we also determine the list of files reachable * and hang them on the tfile_check_list, so we can check that we * haven't created too many possible wakeup paths. |
22bacca48 epoll: prevent cr... |
1768 |
* |
28d82dc1c epoll: limit paths |
1769 1770 1771 |
* We need to hold the epmutex across both ep_insert and ep_remove * b/c we want to make sure we are looking at a coherent view of * epoll network. |
22bacca48 epoll: prevent cr... |
1772 |
*/ |
28d82dc1c epoll: limit paths |
1773 |
if (op == EPOLL_CTL_ADD || op == EPOLL_CTL_DEL) { |
22bacca48 epoll: prevent cr... |
1774 1775 |
mutex_lock(&epmutex); did_lock_epmutex = 1; |
22bacca48 epoll: prevent cr... |
1776 |
} |
28d82dc1c epoll: limit paths |
1777 |
if (op == EPOLL_CTL_ADD) { |
7e3fb5842 switch epoll_ctl(... |
1778 |
if (is_file_epoll(tf.file)) { |
28d82dc1c epoll: limit paths |
1779 |
error = -ELOOP; |
7e3fb5842 switch epoll_ctl(... |
1780 |
if (ep_loop_check(ep, tf.file) != 0) { |
13d518074 epoll: clear the ... |
1781 |
clear_tfile_check_list(); |
28d82dc1c epoll: limit paths |
1782 |
goto error_tgt_fput; |
13d518074 epoll: clear the ... |
1783 |
} |
28d82dc1c epoll: limit paths |
1784 |
} else |
7e3fb5842 switch epoll_ctl(... |
1785 |
list_add(&tf.file->f_tfile_llink, &tfile_check_list); |
28d82dc1c epoll: limit paths |
1786 |
} |
22bacca48 epoll: prevent cr... |
1787 |
|
d8805e633 epoll: fix spurio... |
1788 |
mutex_lock_nested(&ep->mtx, 0); |
7699acd13 epoll cleanups: e... |
1789 |
|
67647d0fb epoll: fix some c... |
1790 1791 1792 1793 1794 |
/* * Try to lookup the file inside our RB tree, Since we grabbed "mtx" * above, we can be sure to be able to use the item looked up by * ep_find() till we release the mutex. */ |
7e3fb5842 switch epoll_ctl(... |
1795 |
epi = ep_find(ep, tf.file, fd); |
7699acd13 epoll cleanups: e... |
1796 1797 1798 1799 1800 1801 |
error = -EINVAL; switch (op) { case EPOLL_CTL_ADD: if (!epi) { epds.events |= POLLERR | POLLHUP; |
7e3fb5842 switch epoll_ctl(... |
1802 |
error = ep_insert(ep, &epds, tf.file, fd); |
7699acd13 epoll cleanups: e... |
1803 1804 |
} else error = -EEXIST; |
28d82dc1c epoll: limit paths |
1805 |
clear_tfile_check_list(); |
7699acd13 epoll cleanups: e... |
1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 |
break; case EPOLL_CTL_DEL: if (epi) error = ep_remove(ep, epi); else error = -ENOENT; break; case EPOLL_CTL_MOD: if (epi) { epds.events |= POLLERR | POLLHUP; error = ep_modify(ep, epi, &epds); } else error = -ENOENT; break; } |
d47de16c7 fix epoll single ... |
1821 |
mutex_unlock(&ep->mtx); |
7699acd13 epoll cleanups: e... |
1822 1823 |
error_tgt_fput: |
28d82dc1c epoll: limit paths |
1824 |
if (did_lock_epmutex) |
22bacca48 epoll: prevent cr... |
1825 |
mutex_unlock(&epmutex); |
7e3fb5842 switch epoll_ctl(... |
1826 |
fdput(tf); |
7699acd13 epoll cleanups: e... |
1827 |
error_fput: |
7e3fb5842 switch epoll_ctl(... |
1828 |
fdput(f); |
7699acd13 epoll cleanups: e... |
1829 |
error_return: |
7699acd13 epoll cleanups: e... |
1830 1831 1832 1833 1834 1835 1836 1837 |
return error; } /* * Implement the event wait interface for the eventpoll file. It is the kernel * part of the user space epoll_wait(2). */ |
5a8a82b1d [CVE-2009-0029] S... |
1838 1839 |
SYSCALL_DEFINE4(epoll_wait, int, epfd, struct epoll_event __user *, events, int, maxevents, int, timeout) |
7699acd13 epoll cleanups: e... |
1840 |
{ |
2903ff019 switch simple cas... |
1841 1842 |
int error; struct fd f; |
7699acd13 epoll cleanups: e... |
1843 |
struct eventpoll *ep; |
7699acd13 epoll cleanups: e... |
1844 1845 1846 1847 1848 |
/* The maximum number of event must be greater than zero */ if (maxevents <= 0 || maxevents > EP_MAX_EVENTS) return -EINVAL; /* Verify that the area passed by the user is writeable */ |
2903ff019 switch simple cas... |
1849 1850 |
if (!access_ok(VERIFY_WRITE, events, maxevents * sizeof(struct epoll_event))) return -EFAULT; |
7699acd13 epoll cleanups: e... |
1851 1852 |
/* Get the "struct file *" for the eventpoll file */ |
2903ff019 switch simple cas... |
1853 1854 1855 |
f = fdget(epfd); if (!f.file) return -EBADF; |
7699acd13 epoll cleanups: e... |
1856 1857 1858 1859 1860 1861 |
/* * We have to check that the file structure underneath the fd * the user passed to us _is_ an eventpoll file. */ error = -EINVAL; |
2903ff019 switch simple cas... |
1862 |
if (!is_file_epoll(f.file)) |
7699acd13 epoll cleanups: e... |
1863 1864 1865 1866 1867 1868 |
goto error_fput; /* * At this point it is safe to assume that the "private_data" contains * our own data structure. */ |
2903ff019 switch simple cas... |
1869 |
ep = f.file->private_data; |
7699acd13 epoll cleanups: e... |
1870 1871 1872 1873 1874 |
/* Time to fish for events ... */ error = ep_poll(ep, events, maxevents, timeout); error_fput: |
2903ff019 switch simple cas... |
1875 |
fdput(f); |
7699acd13 epoll cleanups: e... |
1876 1877 |
return error; } |
7699acd13 epoll cleanups: e... |
1878 1879 1880 1881 |
/* * Implement the event wait interface for the eventpoll file. It is the kernel * part of the user space epoll_pwait(2). */ |
5a8a82b1d [CVE-2009-0029] S... |
1882 1883 1884 |
SYSCALL_DEFINE6(epoll_pwait, int, epfd, struct epoll_event __user *, events, int, maxevents, int, timeout, const sigset_t __user *, sigmask, size_t, sigsetsize) |
7699acd13 epoll cleanups: e... |
1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 |
{ int error; sigset_t ksigmask, sigsaved; /* * If the caller wants a certain signal mask to be set during the wait, * we apply it here. */ if (sigmask) { if (sigsetsize != sizeof(sigset_t)) return -EINVAL; if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask))) return -EFAULT; |
77d559180 signals: eventpol... |
1898 1899 |
sigsaved = current->blocked; set_current_blocked(&ksigmask); |
7699acd13 epoll cleanups: e... |
1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 |
} error = sys_epoll_wait(epfd, events, maxevents, timeout); /* * If we changed the signal mask, we need to restore the original one. * In case we've got a signal while waiting, we do not restore the * signal mask yet, and we allow do_signal() to deliver the signal on * the way back to userspace, before the signal mask is restored. */ if (sigmask) { if (error == -EINTR) { memcpy(¤t->saved_sigmask, &sigsaved, |
c7ea76302 epoll locks chang... |
1913 |
sizeof(sigsaved)); |
4e4c22c71 signals: add set_... |
1914 |
set_restore_sigmask(); |
7699acd13 epoll cleanups: e... |
1915 |
} else |
77d559180 signals: eventpol... |
1916 |
set_current_blocked(&sigsaved); |
7699acd13 epoll cleanups: e... |
1917 1918 1919 1920 |
} return error; } |
35280bd4a switch epoll_pwai... |
1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 |
#ifdef CONFIG_COMPAT COMPAT_SYSCALL_DEFINE6(epoll_pwait, int, epfd, struct epoll_event __user *, events, int, maxevents, int, timeout, const compat_sigset_t __user *, sigmask, compat_size_t, sigsetsize) { long err; compat_sigset_t csigmask; sigset_t ksigmask, sigsaved; /* * If the caller wants a certain signal mask to be set during the wait, * we apply it here. */ if (sigmask) { if (sigsetsize != sizeof(compat_sigset_t)) return -EINVAL; if (copy_from_user(&csigmask, sigmask, sizeof(csigmask))) return -EFAULT; sigset_from_compat(&ksigmask, &csigmask); |
77d559180 signals: eventpol... |
1942 1943 |
sigsaved = current->blocked; set_current_blocked(&ksigmask); |
35280bd4a switch epoll_pwai... |
1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 |
} err = sys_epoll_wait(epfd, events, maxevents, timeout); /* * If we changed the signal mask, we need to restore the original one. * In case we've got a signal while waiting, we do not restore the * signal mask yet, and we allow do_signal() to deliver the signal on * the way back to userspace, before the signal mask is restored. */ if (sigmask) { if (err == -EINTR) { memcpy(¤t->saved_sigmask, &sigsaved, sizeof(sigsaved)); set_restore_sigmask(); } else |
77d559180 signals: eventpol... |
1960 |
set_current_blocked(&sigsaved); |
35280bd4a switch epoll_pwai... |
1961 1962 1963 1964 1965 |
} return err; } #endif |
1da177e4c Linux-2.6.12-rc2 |
1966 1967 |
static int __init eventpoll_init(void) { |
7ef9964e6 epoll: introduce ... |
1968 1969 1970 |
struct sysinfo si; si_meminfo(&si); |
9df04e1f2 epoll: drop max_u... |
1971 1972 1973 1974 |
/* * Allows top 4% of lomem to be allocated for epoll watches (per user). */ max_user_watches = (((si.totalram - si.totalhigh) / 25) << PAGE_SHIFT) / |
7ef9964e6 epoll: introduce ... |
1975 |
EP_ITEM_COST; |
52bd19f76 epoll: convert ma... |
1976 |
BUG_ON(max_user_watches < 0); |
1da177e4c Linux-2.6.12-rc2 |
1977 |
|
22bacca48 epoll: prevent cr... |
1978 1979 1980 1981 1982 |
/* * Initialize the structure used to perform epoll file descriptor * inclusion loops checks. */ ep_nested_calls_init(&poll_loop_ncalls); |
1da177e4c Linux-2.6.12-rc2 |
1983 |
/* Initialize the structure used to perform safe poll wait head wake ups */ |
5071f97ec epoll: fix epoll'... |
1984 1985 1986 1987 |
ep_nested_calls_init(&poll_safewake_ncalls); /* Initialize the structure used to perform file's f_op->poll() calls */ ep_nested_calls_init(&poll_readywalk_ncalls); |
1da177e4c Linux-2.6.12-rc2 |
1988 |
|
39732ca5a epoll: trim epite... |
1989 1990 1991 1992 1993 |
/* * We can have many thousands of epitems, so prevent this from * using an extra cache line on 64-bit (and smaller) CPUs */ BUILD_BUG_ON(sizeof(void *) <= 8 && sizeof(struct epitem) > 128); |
1da177e4c Linux-2.6.12-rc2 |
1994 1995 |
/* Allocates slab cache used to allocate "struct epitem" items */ epi_cache = kmem_cache_create("eventpoll_epi", sizeof(struct epitem), |
bb57c3edc epoll: remove deb... |
1996 |
0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL); |
1da177e4c Linux-2.6.12-rc2 |
1997 1998 1999 |
/* Allocates slab cache used to allocate "struct eppoll_entry" */ pwq_cache = kmem_cache_create("eventpoll_pwq", |
bb57c3edc epoll: remove deb... |
2000 |
sizeof(struct eppoll_entry), 0, SLAB_PANIC, NULL); |
1da177e4c Linux-2.6.12-rc2 |
2001 |
|
1da177e4c Linux-2.6.12-rc2 |
2002 |
return 0; |
1da177e4c Linux-2.6.12-rc2 |
2003 |
} |
cea692418 epoll cleanups: e... |
2004 |
fs_initcall(eventpoll_init); |