diff options
Diffstat (limited to 'fs/eventpoll.c')
| -rw-r--r-- | fs/eventpoll.c | 1626 |
1 files changed, 1214 insertions, 412 deletions
diff --git a/fs/eventpoll.c b/fs/eventpoll.c index a415f42d32c..b10b48c2a7a 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -1,6 +1,6 @@ /* - * fs/eventpoll.c (Efficent event polling implementation) - * Copyright (C) 2001,...,2007 Davide Libenzi + * fs/eventpoll.c (Efficient event retrieval implementation) + * Copyright (C) 2001,...,2009 Davide Libenzi * * 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 @@ -33,11 +33,15 @@ #include <linux/bitops.h> #include <linux/mutex.h> #include <linux/anon_inodes.h> +#include <linux/device.h> #include <asm/uaccess.h> -#include <asm/system.h> #include <asm/io.h> #include <asm/mman.h> -#include <asm/atomic.h> +#include <linux/atomic.h> +#include <linux/proc_fs.h> +#include <linux/seq_file.h> +#include <linux/compat.h> +#include <linux/rculist.h> /* * LOCKING: @@ -62,7 +66,23 @@ * This mutex is acquired by ep_free() during the epoll file * 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 - * close()d without a previous call toepoll_ctl(EPOLL_CTL_DEL). + * close()d without a previous call to epoll_ctl(EPOLL_CTL_DEL). + * 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. + * 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. * 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. @@ -71,71 +91,55 @@ * a better scalability. */ -#define DEBUG_EPOLL 0 - -#if DEBUG_EPOLL > 0 -#define DPRINTK(x) printk x -#define DNPRINTK(n, x) do { if ((n) <= DEBUG_EPOLL) printk x; } while (0) -#else /* #if DEBUG_EPOLL > 0 */ -#define DPRINTK(x) (void) 0 -#define DNPRINTK(n, x) (void) 0 -#endif /* #if DEBUG_EPOLL > 0 */ - -#define DEBUG_EPI 0 - -#if DEBUG_EPI != 0 -#define EPI_SLAB_DEBUG (SLAB_DEBUG_FREE | SLAB_RED_ZONE /* | SLAB_POISON */) -#else /* #if DEBUG_EPI != 0 */ -#define EPI_SLAB_DEBUG 0 -#endif /* #if DEBUG_EPI != 0 */ - /* Epoll private bits inside the event mask */ -#define EP_PRIVATE_BITS (EPOLLONESHOT | EPOLLET) - -/* Maximum number of poll wake up nests we are allowing */ -#define EP_MAX_POLLWAKE_NESTS 4 +#define EP_PRIVATE_BITS (EPOLLWAKEUP | EPOLLONESHOT | EPOLLET) -/* Maximum msec timeout value storeable in a long int */ -#define EP_MAX_MSTIMEO min(1000ULL * MAX_SCHEDULE_TIMEOUT / HZ, (LONG_MAX - 999ULL) / HZ) +/* Maximum number of nesting allowed inside epoll sets */ +#define EP_MAX_NESTS 4 #define EP_MAX_EVENTS (INT_MAX / sizeof(struct epoll_event)) #define EP_UNACTIVE_PTR ((void *) -1L) +#define EP_ITEM_COST (sizeof(struct epitem) + sizeof(struct eppoll_entry)) + struct epoll_filefd { struct file *file; int fd; -}; +} __packed; /* - * Node that is linked into the "wake_task_list" member of the "struct poll_safewake". - * It is used to keep track on all tasks that are currently inside the wake_up() code - * to 1) short-circuit the one coming from the same task and same wait queue head - * (loop) 2) allow a maximum number of epoll descriptors inclusion nesting - * 3) let go the ones coming from other tasks. + * Structure used to track possible nested calls, for too deep recursions + * and loop cycles. */ -struct wake_task_node { +struct nested_call_node { struct list_head llink; - struct task_struct *task; - wait_queue_head_t *wq; + void *cookie; + void *ctx; }; /* - * This is used to implement the safe poll wake up avoiding to reenter - * the poll callback from inside wake_up(). + * This structure is used as collector for nested calls, to check for + * maximum recursion dept and loop cycles. */ -struct poll_safewake { - struct list_head wake_task_list; +struct nested_calls { + struct list_head tasks_call_list; spinlock_t lock; }; /* * Each file descriptor added to the eventpoll interface will * have an entry of this type linked to the "rbr" RB tree. + * 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. */ struct epitem { - /* RB tree node used to link this structure to the eventpoll RB tree */ - struct rb_node rbn; + union { + /* RB tree node links this structure to the eventpoll RB tree */ + struct rb_node rbn; + /* Used to free the struct epitem */ + struct rcu_head rcu; + }; /* List header used to link this structure to the eventpoll ready list */ struct list_head rdllink; @@ -161,17 +165,20 @@ struct epitem { /* List header used to link this item to the "struct file" items list */ struct list_head fllink; + /* wakeup_source used when EPOLLWAKEUP is set */ + struct wakeup_source __rcu *ws; + /* The structure that describe the interested events and the source fd */ struct epoll_event event; }; /* * This structure is stored inside the "private_data" member of the file - * structure and rapresent the main data sructure for the eventpoll + * structure and represents the main data structure for the eventpoll * interface. */ struct eventpoll { - /* Protect the this structure access */ + /* Protect the access to this structure */ spinlock_t lock; /* @@ -196,10 +203,22 @@ struct eventpoll { /* * This is a single linked list that chains all the "struct epitem" that - * happened while transfering ready events to userspace w/out + * happened while transferring ready events to userspace w/out * holding ->lock. */ struct epitem *ovflist; + + /* wakeup_source used when ep_scan_ready_list is running */ + struct wakeup_source *ws; + + /* The user that created the eventpoll descriptor */ + struct user_struct *user; + + struct file *file; + + /* used to optimize loop detection check */ + int visited; + struct list_head visited_list_link; }; /* Wait structure used by the poll hooks */ @@ -208,7 +227,7 @@ struct eppoll_entry { struct list_head llink; /* The "base" pointer is set to the container "struct epitem" */ - void *base; + struct epitem *base; /* * Wait queue item that will be linked to the target file wait @@ -226,13 +245,31 @@ struct ep_pqueue { struct epitem *epi; }; +/* Used by the ep_send_events() function as callback private data */ +struct ep_send_events_data { + int maxevents; + struct epoll_event __user *events; +}; + +/* + * Configuration options available inside /proc/sys/fs/epoll/ + */ +/* Maximum number of epoll watched descriptors, per user */ +static long max_user_watches __read_mostly; + /* * This mutex is used to serialize ep_free() and eventpoll_release_file(). */ -static struct mutex epmutex; +static DEFINE_MUTEX(epmutex); + +/* Used to check for epoll file descriptor inclusion loops */ +static struct nested_calls poll_loop_ncalls; -/* Safe wake up implementation */ -static struct poll_safewake psw; +/* 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; /* Slab cache used to allocate "struct epitem" */ static struct kmem_cache *epi_cache __read_mostly; @@ -240,6 +277,42 @@ static struct kmem_cache *epi_cache __read_mostly; /* Slab cache used to allocate "struct eppoll_entry" */ static struct kmem_cache *pwq_cache __read_mostly; +/* 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); + +#ifdef CONFIG_SYSCTL + +#include <linux/sysctl.h> + +static long zero; +static long long_max = LONG_MAX; + +struct ctl_table epoll_table[] = { + { + .procname = "max_user_watches", + .data = &max_user_watches, + .maxlen = sizeof(max_user_watches), + .mode = 0644, + .proc_handler = proc_doulongvec_minmax, + .extra1 = &zero, + .extra2 = &long_max, + }, + { } +}; +#endif /* CONFIG_SYSCTL */ + +static const struct file_operations eventpoll_fops; + +static inline int is_file_epoll(struct file *f) +{ + return f->f_op == &eventpoll_fops; +} /* Setup the structure that is used as key for the RB tree */ static inline void ep_set_ffd(struct epoll_filefd *ffd, @@ -257,39 +330,25 @@ static inline int ep_cmp_ffd(struct epoll_filefd *p1, (p1->file < p2->file ? -1 : p1->fd - p2->fd)); } -/* Special initialization for the RB tree node to detect linkage */ -static inline void ep_rb_initnode(struct rb_node *n) -{ - rb_set_parent(n, n); -} - -/* Removes a node from the RB tree and marks it for a fast is-linked check */ -static inline void ep_rb_erase(struct rb_node *n, struct rb_root *r) -{ - rb_erase(n, r); - rb_set_parent(n, n); -} - -/* Fast check to verify that the item is linked to the main RB tree */ -static inline int ep_rb_linked(struct rb_node *n) -{ - return rb_parent(n) != n; -} - /* Tells us if the item is currently linked */ static inline int ep_is_linked(struct list_head *p) { return !list_empty(p); } +static inline struct eppoll_entry *ep_pwq_from_wait(wait_queue_t *p) +{ + return container_of(p, struct eppoll_entry, wait); +} + /* Get the "struct epitem" from a wait queue pointer */ -static inline struct epitem * ep_item_from_wait(wait_queue_t *p) +static inline struct epitem *ep_item_from_wait(wait_queue_t *p) { return container_of(p, struct eppoll_entry, wait)->base; } /* Get the "struct epitem" from an epoll queue wrapper */ -static inline struct epitem * ep_item_from_epqueue(poll_table *p) +static inline struct epitem *ep_item_from_epqueue(poll_table *p) { return container_of(p, struct ep_pqueue, pt)->epi; } @@ -301,89 +360,329 @@ static inline int ep_op_has_event(int op) } /* Initialize the poll safe wake up structure */ -static void ep_poll_safewake_init(struct poll_safewake *psw) +static void ep_nested_calls_init(struct nested_calls *ncalls) { + INIT_LIST_HEAD(&ncalls->tasks_call_list); + spin_lock_init(&ncalls->lock); +} - INIT_LIST_HEAD(&psw->wake_task_list); - spin_lock_init(&psw->lock); +/** + * 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; } -/* - * 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_POLLWAKE_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_POLLWAKE_NESTS deep. We need the irq version of the spin lock - * because this one gets called by the poll callback, that in turn is called - * from inside a wake_up(), that might be called from irq context. +/** + * 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. + * @ctx: This instance context. + * + * Returns: Returns the code returned by the @nproc callback, or -1 if + * the maximum recursion limit has been exceeded. */ -static void ep_poll_safewake(struct poll_safewake *psw, wait_queue_head_t *wq) +static int ep_call_nested(struct nested_calls *ncalls, int max_nests, + int (*nproc)(void *, void *, int), void *priv, + void *cookie, void *ctx) { - int wake_nests = 0; + int error, call_nests = 0; unsigned long flags; - struct task_struct *this_task = current; - struct list_head *lsthead = &psw->wake_task_list; - struct wake_task_node *tncur; - struct wake_task_node tnode; + struct list_head *lsthead = &ncalls->tasks_call_list; + struct nested_call_node *tncur; + struct nested_call_node tnode; - spin_lock_irqsave(&psw->lock, flags); + spin_lock_irqsave(&ncalls->lock, flags); - /* Try to see if the current task is already inside this wakeup call */ + /* + * 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. + */ list_for_each_entry(tncur, lsthead, llink) { - - if (tncur->wq == wq || - (tncur->task == this_task && ++wake_nests > EP_MAX_POLLWAKE_NESTS)) { + if (tncur->ctx == ctx && + (tncur->cookie == cookie || ++call_nests > max_nests)) { /* * Ops ... loop detected or maximum nest level reached. * We abort this wake by breaking the cycle itself. */ - spin_unlock_irqrestore(&psw->lock, flags); - return; + error = -1; + goto out_unlock; } } - /* Add the current task to the list */ - tnode.task = this_task; - tnode.wq = wq; + /* Add the current task and cookie to the list */ + tnode.ctx = ctx; + tnode.cookie = cookie; list_add(&tnode.llink, lsthead); - spin_unlock_irqrestore(&psw->lock, flags); + spin_unlock_irqrestore(&ncalls->lock, flags); - /* Do really wake up now */ - wake_up_nested(wq, 1 + wake_nests); + /* Call the nested function */ + error = (*nproc)(priv, cookie, call_nests); /* Remove the current task from the list */ - spin_lock_irqsave(&psw->lock, flags); + spin_lock_irqsave(&ncalls->lock, flags); list_del(&tnode.llink); - spin_unlock_irqrestore(&psw->lock, flags); +out_unlock: + spin_unlock_irqrestore(&ncalls->lock, flags); + + return error; } /* - * This function unregister poll callbacks from the associated file descriptor. - * Since this must be called without holding "ep->lock" the atomic exchange trick - * will protect us from multiple unregister. + * 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. + */ +#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 + +static int ep_poll_wakeup_proc(void *priv, void *cookie, int call_nests) +{ + ep_wake_up_nested((wait_queue_head_t *) cookie, POLLIN, + 1 + call_nests); + 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) +{ + int this_cpu = get_cpu(); + + ep_call_nested(&poll_safewake_ncalls, EP_MAX_NESTS, + ep_poll_wakeup_proc, NULL, wq, (void *) (long) this_cpu); + + put_cpu(); +} + +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(); +} + +/* + * This function unregisters poll callbacks from the associated file + * descriptor. Must be called with "mtx" held (or "epmutex" if called from + * ep_free). */ static void ep_unregister_pollwait(struct eventpoll *ep, struct epitem *epi) { - int nwait; struct list_head *lsthead = &epi->pwqlist; struct eppoll_entry *pwq; - /* This is called without locks, so we need the atomic exchange */ - nwait = xchg(&epi->nwait, 0); + while (!list_empty(lsthead)) { + pwq = list_first_entry(lsthead, struct eppoll_entry, llink); + + list_del(&pwq->llink); + ep_remove_wait_queue(pwq); + kmem_cache_free(pwq_cache, pwq); + } +} + +/* 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(); +} + +/** + * 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. + * @depth: The current depth of recursive f_op->poll calls. + * @ep_locked: caller already holds ep->mtx + * + * 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 *), + void *priv, int depth, bool ep_locked) +{ + int error, pwake = 0; + unsigned long flags; + struct epitem *epi, *nepi; + LIST_HEAD(txlist); + + /* + * We need to lock this because we could be hit by + * eventpoll_release_file() and epoll_ctl(). + */ + + if (!ep_locked) + mutex_lock_nested(&ep->mtx, depth); + + /* + * 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); + list_splice_init(&ep->rdllist, &txlist); + ep->ovflist = NULL; + spin_unlock_irqrestore(&ep->lock, flags); - if (nwait) { - while (!list_empty(lsthead)) { - pwq = list_first_entry(lsthead, struct eppoll_entry, llink); + /* + * Now call the callback function. + */ + error = (*sproc)(ep, &txlist, priv); - list_del_init(&pwq->llink); - remove_wait_queue(pwq->whead, &pwq->wait); - kmem_cache_free(pwq_cache, pwq); + 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. + */ + if (!ep_is_linked(&epi->rdllink)) { + list_add_tail(&epi->rdllink, &ep->rdllist); + ep_pm_stay_awake(epi); } } + /* + * 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); + __pm_relax(ep->ws); + + if (!list_empty(&ep->rdllist)) { + /* + * Wake up (if active) both the eventpoll wait list and + * the ->poll() wait list (delayed after we release the lock). + */ + if (waitqueue_active(&ep->wq)) + wake_up_locked(&ep->wq); + if (waitqueue_active(&ep->poll_wait)) + pwake++; + } + spin_unlock_irqrestore(&ep->lock, flags); + + if (!ep_locked) + mutex_unlock(&ep->mtx); + + /* We have to call this outside the lock */ + if (pwake) + ep_poll_safewake(&ep->poll_wait); + + return error; +} + +static void epi_rcu_free(struct rcu_head *head) +{ + struct epitem *epi = container_of(head, struct epitem, rcu); + kmem_cache_free(epi_cache, epi); } /* @@ -406,24 +705,28 @@ static int ep_remove(struct eventpoll *ep, struct epitem *epi) ep_unregister_pollwait(ep, epi); /* Remove the current item from the list of epoll hooks */ - spin_lock(&file->f_ep_lock); - if (ep_is_linked(&epi->fllink)) - list_del_init(&epi->fllink); - spin_unlock(&file->f_ep_lock); + spin_lock(&file->f_lock); + list_del_rcu(&epi->fllink); + spin_unlock(&file->f_lock); - if (ep_rb_linked(&epi->rbn)) - ep_rb_erase(&epi->rbn, &ep->rbr); + rb_erase(&epi->rbn, &ep->rbr); spin_lock_irqsave(&ep->lock, flags); if (ep_is_linked(&epi->rdllink)) list_del_init(&epi->rdllink); spin_unlock_irqrestore(&ep->lock, flags); - /* At this point it is safe to free the eventpoll item */ - kmem_cache_free(epi_cache, epi); + wakeup_source_unregister(ep_wakeup_source(epi)); + /* + * At this point it is safe to free the eventpoll item. Use the union + * field epi->rcu, since we are trying to minimize the size of + * 'struct epitem'. The 'rbn' field is no longer in use. Protected by + * ep->mtx. The rcu read side, reverse_path_check_proc(), does not make + * use of the rbn field. + */ + call_rcu(&epi->rcu, epi_rcu_free); - DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_remove(%p, %p)\n", - current, ep, file)); + atomic_long_dec(&ep->user->epoll_watches); return 0; } @@ -435,7 +738,7 @@ static void ep_free(struct eventpoll *ep) /* We need to release all tasks waiting for these file */ if (waitqueue_active(&ep->poll_wait)) - ep_poll_safewake(&psw, &ep->poll_wait); + ep_poll_safewake(&ep->poll_wait); /* * We need to lock this because we could be hit by @@ -443,7 +746,7 @@ static void ep_free(struct eventpoll *ep) * We do not need to hold "ep->mtx" here because the epoll file * 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 - * holding "epmutex" is sufficent here. + * holding "epmutex" is sufficient here. */ mutex_lock(&epmutex); @@ -454,6 +757,7 @@ static void ep_free(struct eventpoll *ep) epi = rb_entry(rbp, struct epitem, rbn); ep_unregister_pollwait(ep, epi); + cond_resched(); } /* @@ -461,14 +765,21 @@ static void ep_free(struct eventpoll *ep) * point we are sure no poll callbacks will be lingering around, and also by * holding "epmutex" we can be sure that no file cleanup code will hit * us during this operation. So we can avoid the lock on "ep->lock". + * We do not need to lock ep->mtx, either, we only do it to prevent + * a lockdep warning. */ + mutex_lock(&ep->mtx); while ((rbp = rb_first(&ep->rbr)) != NULL) { epi = rb_entry(rbp, struct epitem, rbn); ep_remove(ep, epi); + cond_resched(); } + mutex_unlock(&ep->mtx); mutex_unlock(&epmutex); mutex_destroy(&ep->mtx); + free_uid(ep->user); + wakeup_source_unregister(ep->ws); kfree(ep); } @@ -479,40 +790,118 @@ static int ep_eventpoll_release(struct inode *inode, struct file *file) if (ep) ep_free(ep); - DNPRINTK(3, (KERN_INFO "[%p] eventpoll: close() ep=%p\n", current, ep)); return 0; } +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; +} + +static int ep_read_events_proc(struct eventpoll *ep, struct list_head *head, + void *priv) +{ + struct epitem *epi, *tmp; + poll_table pt; + + init_poll_funcptr(&pt, NULL); + + list_for_each_entry_safe(epi, tmp, head, rdllink) { + if (ep_item_poll(epi, &pt)) + return POLLIN | POLLRDNORM; + else { + /* + * 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. + */ + __pm_relax(ep_wakeup_source(epi)); + list_del_init(&epi->rdllink); + } + } + + return 0; +} + +static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead, + poll_table *pt); + +struct readyevents_arg { + struct eventpoll *ep; + bool locked; +}; + +static int ep_poll_readyevents_proc(void *priv, void *cookie, int call_nests) +{ + struct readyevents_arg *arg = priv; + + return ep_scan_ready_list(arg->ep, ep_read_events_proc, NULL, + call_nests + 1, arg->locked); +} + static unsigned int ep_eventpoll_poll(struct file *file, poll_table *wait) { - unsigned int pollflags = 0; - unsigned long flags; + int pollflags; struct eventpoll *ep = file->private_data; + struct readyevents_arg arg; + + /* + * During ep_insert() we already hold the ep->mtx for the tfile. + * Prevent re-aquisition. + */ + arg.locked = wait && (wait->_qproc == ep_ptable_queue_proc); + arg.ep = ep; /* Insert inside our poll wait queue */ poll_wait(file, &ep->poll_wait, wait); - /* Check our condition */ - spin_lock_irqsave(&ep->lock, flags); - if (!list_empty(&ep->rdllist)) - pollflags = POLLIN | POLLRDNORM; - spin_unlock_irqrestore(&ep->lock, flags); + /* + * 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, + ep_poll_readyevents_proc, &arg, ep, current); + + return pollflags != -1 ? pollflags : 0; +} + +#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); - return pollflags; + ret = seq_printf(m, "tfd: %8d events: %8x data: %16llx\n", + epi->ffd.fd, epi->event.events, + (long long)epi->event.data); + if (ret) + break; + } + mutex_unlock(&ep->mtx); + + return ret; } +#endif /* File callbacks that implement the eventpoll file behaviour */ static const struct file_operations eventpoll_fops = { +#ifdef CONFIG_PROC_FS + .show_fdinfo = ep_show_fdinfo, +#endif .release = ep_eventpoll_release, - .poll = ep_eventpoll_poll + .poll = ep_eventpoll_poll, + .llseek = noop_llseek, }; -/* Fast test to see if the file is an evenpoll file */ -static inline int is_file_epoll(struct file *f) -{ - return f->f_op == &eventpoll_fops; -} - /* * 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 @@ -520,42 +909,43 @@ static inline int is_file_epoll(struct file *f) */ void eventpoll_release_file(struct file *file) { - struct list_head *lsthead = &file->f_ep_links; struct eventpoll *ep; - struct epitem *epi; + struct epitem *epi, *next; /* - * We don't want to get "file->f_ep_lock" because it is not + * We don't want to get "file->f_lock" because it is not * necessary. It is not necessary because we're in the "struct file" - * cleanup path, and this means that noone is using this file anymore. - * So, for example, epoll_ctl() cannot hit here sicne if we reach this + * cleanup path, and this means that no one is using this file anymore. + * So, for example, epoll_ctl() cannot hit here since if we reach this * point, the file counter already went to zero and fget() would fail. * The only hit might come from ep_free() but by holding the mutex * will correctly serialize the operation. We do need to acquire * "ep->mtx" after "epmutex" because ep_remove() requires it when called * from anywhere but ep_free(). + * + * Besides, ep_remove() acquires the lock, so we can't hold it here. */ mutex_lock(&epmutex); - - while (!list_empty(lsthead)) { - epi = list_first_entry(lsthead, struct epitem, fllink); - + list_for_each_entry_safe(epi, next, &file->f_ep_links, fllink) { ep = epi->ep; - list_del_init(&epi->fllink); - mutex_lock(&ep->mtx); + mutex_lock_nested(&ep->mtx, 0); ep_remove(ep, epi); mutex_unlock(&ep->mtx); } - mutex_unlock(&epmutex); } static int ep_alloc(struct eventpoll **pep) { - struct eventpoll *ep = kzalloc(sizeof(*ep), GFP_KERNEL); + int error; + struct user_struct *user; + struct eventpoll *ep; - if (!ep) - return -ENOMEM; + user = get_current_user(); + error = -ENOMEM; + ep = kzalloc(sizeof(*ep), GFP_KERNEL); + if (unlikely(!ep)) + goto free_uid; spin_lock_init(&ep->lock); mutex_init(&ep->mtx); @@ -564,12 +954,15 @@ static int ep_alloc(struct eventpoll **pep) INIT_LIST_HEAD(&ep->rdllist); ep->rbr = RB_ROOT; ep->ovflist = EP_UNACTIVE_PTR; + ep->user = user; *pep = ep; - DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_alloc() ep=%p\n", - current, ep)); return 0; + +free_uid: + free_uid(user); + return error; } /* @@ -598,15 +991,12 @@ static struct epitem *ep_find(struct eventpoll *ep, struct file *file, int fd) } } - DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_find(%p) -> %p\n", - current, file, epir)); - return epir; } /* * This is the callback that is passed to the wait queue wakeup - * machanism. It is called by the stored file descriptors when they + * mechanism. It is called by the stored file descriptors when they * have events to report. */ static int ep_poll_callback(wait_queue_t *wait, unsigned mode, int sync, void *key) @@ -616,8 +1006,16 @@ static int ep_poll_callback(wait_queue_t *wait, unsigned mode, int sync, void *k struct epitem *epi = ep_item_from_wait(wait); struct eventpoll *ep = epi->ep; - DNPRINTK(3, (KERN_INFO "[%p] eventpoll: poll_callback(%p) epi=%p ep=%p\n", - current, epi->ffd.file, epi, ep)); + 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. + */ + list_del_init(&wait->task_list); + } spin_lock_irqsave(&ep->lock, flags); @@ -631,26 +1029,42 @@ static int ep_poll_callback(wait_queue_t *wait, unsigned mode, int sync, void *k goto out_unlock; /* - * If we are trasfering events to userspace, we can hold no locks + * 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; + + /* + * If we are transferring events to userspace, we can hold no locks * (because we're accessing user memory, and because of linux f_op->poll() - * semantics). All the events that happens during that period of time are + * semantics). All the events that happen during that period of time are * 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; + if (epi->ws) { + /* + * Activate ep->ws since epi->ws may get + * deactivated at any time. + */ + __pm_stay_awake(ep->ws); + } + } goto out_unlock; } /* If this file is already in the ready list we exit soon */ - if (ep_is_linked(&epi->rdllink)) - goto is_linked; - - list_add_tail(&epi->rdllink, &ep->rdllist); + if (!ep_is_linked(&epi->rdllink)) { + list_add_tail(&epi->rdllink, &ep->rdllist); + ep_pm_stay_awake_rcu(epi); + } -is_linked: /* * Wake up ( if active ) both the eventpoll wait list and the ->poll() * wait list. @@ -665,7 +1079,7 @@ out_unlock: /* We have to call this outside the lock */ if (pwake) - ep_poll_safewake(&psw, &ep->poll_wait); + ep_poll_safewake(&ep->poll_wait); return 1; } @@ -712,23 +1126,160 @@ static void ep_rbtree_insert(struct eventpoll *ep, struct epitem *epi) rb_insert_color(&epi->rbn, &ep->rbr); } + + +#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) +{ + /* Allow an arbitrary number of depth 1 paths */ + if (nests == 0) + return 0; + + 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; + + /* CTL_DEL can remove links here, but that can't increase our count */ + rcu_read_lock(); + list_for_each_entry_rcu(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!\n"); + } + } + rcu_read_unlock(); + 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) +{ + 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) { + 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; +} + +static int ep_create_wakeup_source(struct epitem *epi) +{ + const char *name; + struct wakeup_source *ws; + + 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; + ws = wakeup_source_register(name); + + if (!ws) + return -ENOMEM; + rcu_assign_pointer(epi->ws, ws); + + return 0; +} + +/* rare code path, only used when EPOLL_CTL_MOD removes a wakeup source */ +static noinline void ep_destroy_wakeup_source(struct epitem *epi) +{ + struct wakeup_source *ws = ep_wakeup_source(epi); + + RCU_INIT_POINTER(epi->ws, NULL); + + /* + * 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); +} + /* * Must be called with "mtx" held. */ static int ep_insert(struct eventpoll *ep, struct epoll_event *event, - struct file *tfile, int fd) + struct file *tfile, int fd, int full_check) { int error, revents, pwake = 0; unsigned long flags; + long user_watches; struct epitem *epi; struct ep_pqueue epq; - error = -ENOMEM; + user_watches = atomic_long_read(&ep->user->epoll_watches); + if (unlikely(user_watches >= max_user_watches)) + return -ENOSPC; if (!(epi = kmem_cache_alloc(epi_cache, GFP_KERNEL))) - goto error_return; + return -ENOMEM; /* Item initialization follow here ... */ - ep_rb_initnode(&epi->rbn); INIT_LIST_HEAD(&epi->rdllink); INIT_LIST_HEAD(&epi->fllink); INIT_LIST_HEAD(&epi->pwqlist); @@ -737,6 +1288,13 @@ static int ep_insert(struct eventpoll *ep, struct epoll_event *event, epi->event = *event; epi->nwait = 0; epi->next = EP_UNACTIVE_PTR; + if (epi->event.events & EPOLLWAKEUP) { + error = ep_create_wakeup_source(epi); + if (error) + goto error_create_wakeup_source; + } else { + RCU_INIT_POINTER(epi->ws, NULL); + } /* Initialize the poll table using the queue callback */ epq.epi = epi; @@ -749,20 +1307,21 @@ static int ep_insert(struct eventpoll *ep, struct epoll_event *event, * this operation completes, the poll callback can start hitting * the new item. */ - revents = tfile->f_op->poll(tfile, &epq.pt); + revents = ep_item_poll(epi, &epq.pt); /* * 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. */ + error = -ENOMEM; if (epi->nwait < 0) goto error_unregister; /* Add the current item to the list of active epoll hook for this file */ - spin_lock(&tfile->f_ep_lock); - list_add_tail(&epi->fllink, &tfile->f_ep_links); - spin_unlock(&tfile->f_ep_lock); + spin_lock(&tfile->f_lock); + list_add_tail_rcu(&epi->fllink, &tfile->f_ep_links); + spin_unlock(&tfile->f_lock); /* * Add the current item to the RB tree. All RB tree operations are @@ -770,12 +1329,18 @@ static int ep_insert(struct eventpoll *ep, struct epoll_event *event, */ ep_rbtree_insert(ep, epi); + /* now check if we've created too many backpaths */ + error = -EINVAL; + if (full_check && reverse_path_check()) + goto error_remove_epi; + /* We have to drop the new item inside our item list to keep track of it */ spin_lock_irqsave(&ep->lock, flags); /* If the file is already "ready" we drop it inside the ready list */ if ((revents & event->events) && !ep_is_linked(&epi->rdllink)) { list_add_tail(&epi->rdllink, &ep->rdllist); + ep_pm_stay_awake(epi); /* Notify waiting tasks that events are available */ if (waitqueue_active(&ep->wq)) @@ -786,15 +1351,21 @@ static int ep_insert(struct eventpoll *ep, struct epoll_event *event, spin_unlock_irqrestore(&ep->lock, flags); + atomic_long_inc(&ep->user->epoll_watches); + /* We have to call this outside the lock */ if (pwake) - ep_poll_safewake(&psw, &ep->poll_wait); - - DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_insert(%p, %p, %d)\n", - current, ep, tfile, fd)); + ep_poll_safewake(&ep->poll_wait); return 0; +error_remove_epi: + spin_lock(&tfile->f_lock); + list_del_rcu(&epi->fllink); + spin_unlock(&tfile->f_lock); + + rb_erase(&epi->rbn, &ep->rbr); + error_unregister: ep_unregister_pollwait(ep, epi); @@ -809,8 +1380,11 @@ error_unregister: list_del_init(&epi->rdllink); spin_unlock_irqrestore(&ep->lock, flags); + wakeup_source_unregister(ep_wakeup_source(epi)); + +error_create_wakeup_source: kmem_cache_free(epi_cache, epi); -error_return: + return error; } @@ -822,34 +1396,59 @@ static int ep_modify(struct eventpoll *ep, struct epitem *epi, struct epoll_even { int pwake = 0; unsigned int revents; - unsigned long flags; + poll_table pt; + + init_poll_funcptr(&pt, NULL); + + /* + * 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. + */ + epi->event.events = event->events; /* need barrier below */ + epi->event.data = event->data; /* protected by mtx */ + if (epi->event.events & EPOLLWAKEUP) { + if (!ep_has_wakeup_source(epi)) + ep_create_wakeup_source(epi); + } else if (ep_has_wakeup_source(epi)) { + ep_destroy_wakeup_source(epi); + } /* - * Set the new event interest mask before calling f_op->poll(), otherwise - * a potential race might occur. In fact if we do this operation inside - * the lock, an event might happen between the f_op->poll() call and the - * new event set registering. + * 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. */ - epi->event.events = event->events; + smp_mb(); /* * Get current event bits. We can safely use the file* here because * its usage count has been increased by the caller of this function. */ - revents = epi->ffd.file->f_op->poll(epi->ffd.file, NULL); - - spin_lock_irqsave(&ep->lock, flags); - - /* Copy the data member from inside the lock */ - epi->event.data = event->data; + revents = ep_item_poll(epi, &pt); /* * If the item is "hot" and it is not registered inside the ready * list, push it inside. */ if (revents & event->events) { + spin_lock_irq(&ep->lock); if (!ep_is_linked(&epi->rdllink)) { list_add_tail(&epi->rdllink, &ep->rdllist); + ep_pm_stay_awake(epi); /* Notify waiting tasks that events are available */ if (waitqueue_active(&ep->wq)) @@ -857,169 +1456,171 @@ static int ep_modify(struct eventpoll *ep, struct epitem *epi, struct epoll_even if (waitqueue_active(&ep->poll_wait)) pwake++; } + spin_unlock_irq(&ep->lock); } - spin_unlock_irqrestore(&ep->lock, flags); /* We have to call this outside the lock */ if (pwake) - ep_poll_safewake(&psw, &ep->poll_wait); + ep_poll_safewake(&ep->poll_wait); return 0; } -static int ep_send_events(struct eventpoll *ep, struct epoll_event __user *events, - int maxevents) +static int ep_send_events_proc(struct eventpoll *ep, struct list_head *head, + void *priv) { - int eventcnt, error = -EFAULT, pwake = 0; + struct ep_send_events_data *esed = priv; + int eventcnt; unsigned int revents; - unsigned long flags; - struct epitem *epi, *nepi; - struct list_head txlist; - - INIT_LIST_HEAD(&txlist); + struct epitem *epi; + struct epoll_event __user *uevent; + struct wakeup_source *ws; + poll_table pt; - /* - * We need to lock this because we could be hit by - * eventpoll_release_file() and epoll_ctl(EPOLL_CTL_DEL). - */ - mutex_lock(&ep->mtx); + init_poll_funcptr(&pt, NULL); /* - * 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 are doing it in the loop below, in a lockless way. + * 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. */ - spin_lock_irqsave(&ep->lock, flags); - list_splice(&ep->rdllist, &txlist); - INIT_LIST_HEAD(&ep->rdllist); - ep->ovflist = NULL; - spin_unlock_irqrestore(&ep->lock, flags); + for (eventcnt = 0, uevent = esed->events; + !list_empty(head) && eventcnt < esed->maxevents;) { + epi = list_first_entry(head, struct epitem, rdllink); - /* - * We can loop without lock because this is a task private list. - * We just splice'd out the ep->rdllist in ep_collect_ready_items(). - * Items cannot vanish during the loop because we are holding "mtx". - */ - for (eventcnt = 0; !list_empty(&txlist) && eventcnt < maxevents;) { - epi = list_first_entry(&txlist, struct epitem, rdllink); + /* + * 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(). + */ + ws = ep_wakeup_source(epi); + if (ws) { + if (ws->active) + __pm_stay_awake(ep->ws); + __pm_relax(ws); + } list_del_init(&epi->rdllink); - /* - * Get the ready file event set. We can safely use the file - * because we are holding the "mtx" and this will guarantee - * that both the file and the item will not vanish. - */ - revents = epi->ffd.file->f_op->poll(epi->ffd.file, NULL); - revents &= epi->event.events; + revents = ep_item_poll(epi, &pt); /* - * Is the event mask intersect the caller-requested one, - * deliver the event to userspace. Again, we are holding - * "mtx", so no operations coming from userspace can change - * the item. + * 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. */ if (revents) { - if (__put_user(revents, - &events[eventcnt].events) || - __put_user(epi->event.data, - &events[eventcnt].data)) - goto errxit; + if (__put_user(revents, &uevent->events) || + __put_user(epi->event.data, &uevent->data)) { + list_add(&epi->rdllink, head); + ep_pm_stay_awake(epi); + return eventcnt ? eventcnt : -EFAULT; + } + eventcnt++; + uevent++; if (epi->event.events & EPOLLONESHOT) epi->event.events &= EP_PRIVATE_BITS; - eventcnt++; + 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 + * availability. At this point, no one can insert + * 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); + ep_pm_stay_awake(epi); + } } - /* - * At this point, noone can insert into ep->rdllist besides - * us. The epoll_ctl() callers are locked out by us holding - * "mtx" and the poll callback will queue them in ep->ovflist. - */ - if (!(epi->event.events & EPOLLET) && - (revents & epi->event.events)) - list_add_tail(&epi->rdllink, &ep->rdllist); } - error = 0; -errxit: + return eventcnt; +} - spin_lock_irqsave(&ep->lock, flags); - /* - * During the time we spent in the loop above, some other events - * might have been queued by the poll callback. We re-insert them - * here (in case they are not already queued, or they're one-shot). - */ - for (nepi = ep->ovflist; (epi = nepi) != NULL; - nepi = epi->next, epi->next = EP_UNACTIVE_PTR) { - if (!ep_is_linked(&epi->rdllink) && - (epi->event.events & ~EP_PRIVATE_BITS)) - list_add_tail(&epi->rdllink, &ep->rdllist); - } - /* - * 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; +static int ep_send_events(struct eventpoll *ep, + struct epoll_event __user *events, int maxevents) +{ + struct ep_send_events_data esed; - /* - * In case of error in the event-send loop, or in case the number of - * ready events exceeds the userspace limit, we need to splice the - * "txlist" back inside ep->rdllist. - */ - list_splice(&txlist, &ep->rdllist); + esed.maxevents = maxevents; + esed.events = events; - if (!list_empty(&ep->rdllist)) { - /* - * Wake up (if active) both the eventpoll wait list and the ->poll() - * wait list (delayed after we release the lock). - */ - 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); + return ep_scan_ready_list(ep, ep_send_events_proc, &esed, 0, false); +} - /* We have to call this outside the lock */ - if (pwake) - ep_poll_safewake(&psw, &ep->poll_wait); +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), + }; - return eventcnt == 0 ? error: eventcnt; + ktime_get_ts(&now); + return timespec_add_safe(now, ts); } +/** + * 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. + */ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events, int maxevents, long timeout) { - int res, eavail; + int res = 0, eavail, timed_out = 0; unsigned long flags; - long jtimeout; + long slack = 0; wait_queue_t wait; + ktime_t expires, *to = NULL; - /* - * Calculate the timeout by checking for the "infinite" value ( -1 ) - * and the overflow condition. The passed timeout is in milliseconds, - * that why (t * HZ) / 1000. - */ - jtimeout = (timeout < 0 || timeout >= EP_MAX_MSTIMEO) ? - MAX_SCHEDULE_TIMEOUT : (timeout * HZ + 999) / 1000; + if (timeout > 0) { + struct timespec end_time = ep_set_mstimeout(timeout); + + slack = select_estimate_accuracy(&end_time); + to = &expires; + *to = timespec_to_ktime(end_time); + } else if (timeout == 0) { + /* + * Avoid the unnecessary trip to the wait queue loop, if the + * caller specified a non blocking operation. + */ + timed_out = 1; + spin_lock_irqsave(&ep->lock, flags); + goto check_events; + } -retry: +fetch_events: spin_lock_irqsave(&ep->lock, flags); - res = 0; - if (list_empty(&ep->rdllist)) { + if (!ep_events_available(ep)) { /* * 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); - wait.flags |= WQ_FLAG_EXCLUSIVE; - __add_wait_queue(&ep->wq, &wait); + __add_wait_queue_exclusive(&ep->wq, &wait); for (;;) { /* @@ -1028,7 +1629,7 @@ retry: * to TASK_INTERRUPTIBLE before doing the checks. */ set_current_state(TASK_INTERRUPTIBLE); - if (!list_empty(&ep->rdllist) || !jtimeout) + if (ep_events_available(ep) || timed_out) break; if (signal_pending(current)) { res = -EINTR; @@ -1036,16 +1637,18 @@ retry: } spin_unlock_irqrestore(&ep->lock, flags); - jtimeout = schedule_timeout(jtimeout); + if (!schedule_hrtimeout_range(to, slack, HRTIMER_MODE_ABS)) + timed_out = 1; + spin_lock_irqsave(&ep->lock, flags); } __remove_wait_queue(&ep->wq, &wait); set_current_state(TASK_RUNNING); } - +check_events: /* Is it worth to try to dig for events ? */ - eavail = !list_empty(&ep->rdllist); + eavail = ep_events_available(ep); spin_unlock_irqrestore(&ep->lock, flags); @@ -1055,129 +1658,273 @@ retry: * more luck. */ if (!res && eavail && - !(res = ep_send_events(ep, events, maxevents)) && jtimeout) - goto retry; + !(res = ep_send_events(ep, events, maxevents)) && !timed_out) + goto fetch_events; return res; } +/** + * 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; + struct eventpoll *ep_tovisit; + struct rb_node *rbp; + struct epitem *epi; + + mutex_lock_nested(&ep->mtx, call_nests + 1); + ep->visited = 1; + list_add(&ep->visited_list_link, &visited_list); + 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))) { + ep_tovisit = epi->ffd.file->private_data; + if (ep_tovisit->visited) + continue; + error = ep_call_nested(&poll_loop_ncalls, EP_MAX_NESTS, + ep_loop_check_proc, epi->ffd.file, + ep_tovisit, current); + if (error != 0) + break; + } 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); + } + } + 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) +{ + int ret; + struct eventpoll *ep_cur, *ep_next; + + ret = ep_call_nested(&poll_loop_ncalls, EP_MAX_NESTS, + ep_loop_check_proc, file, ep, current); + /* 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); +} + /* - * It opens an eventpoll file descriptor. The "size" parameter is there - * for historical reasons, when epoll was using an hash instead of an - * RB tree. With the current implementation, the "size" parameter is ignored - * (besides sanity checks). + * Open an eventpoll file descriptor. */ -asmlinkage long sys_epoll_create(int size) +SYSCALL_DEFINE1(epoll_create1, int, flags) { - int error, fd = -1; - struct eventpoll *ep; - struct inode *inode; + int error, fd; + struct eventpoll *ep = NULL; struct file *file; - DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_create(%d)\n", - current, size)); + /* Check the EPOLL_* constant for consistency. */ + BUILD_BUG_ON(EPOLL_CLOEXEC != O_CLOEXEC); + if (flags & ~EPOLL_CLOEXEC) + return -EINVAL; /* - * Sanity check on the size parameter, and create the internal data - * structure ( "struct eventpoll" ). + * Create the internal data structure ("struct eventpoll"). */ - error = -EINVAL; - if (size <= 0 || (error = ep_alloc(&ep)) != 0) - goto error_return; - + error = ep_alloc(&ep); + if (error < 0) + return error; /* * Creates all the items needed to setup an eventpoll file. That is, - * a file structure, and inode and a free file descriptor. + * a file structure and a free file descriptor. */ - error = anon_inode_getfd(&fd, &inode, &file, "[eventpoll]", - &eventpoll_fops, ep); - if (error) - goto error_free; - - DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_create(%d) = %d\n", - current, size, fd)); - + 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, + O_RDWR | (flags & O_CLOEXEC)); + if (IS_ERR(file)) { + error = PTR_ERR(file); + goto out_free_fd; + } + ep->file = file; + fd_install(fd, file); return fd; -error_free: +out_free_fd: + put_unused_fd(fd); +out_free_ep: ep_free(ep); -error_return: - DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_create(%d) = %d\n", - current, size, error)); return error; } +SYSCALL_DEFINE1(epoll_create, int, size) +{ + if (size <= 0) + return -EINVAL; + + return sys_epoll_create1(0); +} + /* * The following function implements the controller interface for * the eventpoll file that enables the insertion/removal/change of * file descriptors inside the interest set. */ -asmlinkage long sys_epoll_ctl(int epfd, int op, int fd, - struct epoll_event __user *event) +SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd, + struct epoll_event __user *, event) { int error; - struct file *file, *tfile; + int full_check = 0; + struct fd f, tf; struct eventpoll *ep; struct epitem *epi; struct epoll_event epds; - - DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_ctl(%d, %d, %d, %p)\n", - current, epfd, op, fd, event)); + struct eventpoll *tep = NULL; error = -EFAULT; if (ep_op_has_event(op) && copy_from_user(&epds, event, sizeof(struct epoll_event))) goto error_return; - /* Get the "struct file *" for the eventpoll file */ error = -EBADF; - file = fget(epfd); - if (!file) + f = fdget(epfd); + if (!f.file) goto error_return; /* Get the "struct file *" for the target file */ - tfile = fget(fd); - if (!tfile) + tf = fdget(fd); + if (!tf.file) goto error_fput; /* The target file descriptor must support poll */ error = -EPERM; - if (!tfile->f_op || !tfile->f_op->poll) + if (!tf.file->f_op->poll) goto error_tgt_fput; + /* Check if EPOLLWAKEUP is allowed */ + ep_take_care_of_epollwakeup(&epds); + /* * 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; - if (file == tfile || !is_file_epoll(file)) + if (f.file == tf.file || !is_file_epoll(f.file)) goto error_tgt_fput; /* * At this point it is safe to assume that the "private_data" contains * our own data structure. */ - ep = file->private_data; + ep = f.file->private_data; - mutex_lock(&ep->mtx); + /* + * When we insert an epoll file descriptor, inside another epoll file + * descriptor, there is the change of creating closed loops, which are + * 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. + * + * We do not need to take the global 'epumutex' on EPOLL_CTL_ADD when + * the epoll file descriptor is attaching directly to a wakeup source, + * unless the epoll file descriptor is nested. The purpose of taking the + * 'epmutex' on add is to prevent complex toplogies such as loops and + * deep wakeup paths from forming in parallel through multiple + * EPOLL_CTL_ADD operations. + */ + mutex_lock_nested(&ep->mtx, 0); + if (op == EPOLL_CTL_ADD) { + if (!list_empty(&f.file->f_ep_links) || + is_file_epoll(tf.file)) { + full_check = 1; + mutex_unlock(&ep->mtx); + mutex_lock(&epmutex); + if (is_file_epoll(tf.file)) { + error = -ELOOP; + if (ep_loop_check(ep, tf.file) != 0) { + clear_tfile_check_list(); + goto error_tgt_fput; + } + } else + list_add(&tf.file->f_tfile_llink, + &tfile_check_list); + mutex_lock_nested(&ep->mtx, 0); + if (is_file_epoll(tf.file)) { + tep = tf.file->private_data; + mutex_lock_nested(&tep->mtx, 1); + } + } + } /* * 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. */ - epi = ep_find(ep, tfile, fd); + epi = ep_find(ep, tf.file, fd); error = -EINVAL; switch (op) { case EPOLL_CTL_ADD: if (!epi) { epds.events |= POLLERR | POLLHUP; - - error = ep_insert(ep, &epds, tfile, fd); + error = ep_insert(ep, &epds, tf.file, fd, full_check); } else error = -EEXIST; + if (full_check) + clear_tfile_check_list(); break; case EPOLL_CTL_DEL: if (epi) @@ -1193,15 +1940,18 @@ asmlinkage long sys_epoll_ctl(int epfd, int op, int fd, error = -ENOENT; break; } + if (tep != NULL) + mutex_unlock(&tep->mtx); mutex_unlock(&ep->mtx); error_tgt_fput: - fput(tfile); + if (full_check) + mutex_unlock(&epmutex); + + fdput(tf); error_fput: - fput(file); + fdput(f); error_return: - DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_ctl(%d, %d, %d, %p) = %d\n", - current, epfd, op, fd, event, error)); return error; } @@ -1210,67 +1960,55 @@ error_return: * Implement the event wait interface for the eventpoll file. It is the kernel * part of the user space epoll_wait(2). */ -asmlinkage long sys_epoll_wait(int epfd, struct epoll_event __user *events, - int maxevents, int timeout) +SYSCALL_DEFINE4(epoll_wait, int, epfd, struct epoll_event __user *, events, + int, maxevents, int, timeout) { int error; - struct file *file; + struct fd f; struct eventpoll *ep; - DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_wait(%d, %p, %d, %d)\n", - current, epfd, events, maxevents, timeout)); - /* 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 */ - if (!access_ok(VERIFY_WRITE, events, maxevents * sizeof(struct epoll_event))) { - error = -EFAULT; - goto error_return; - } + if (!access_ok(VERIFY_WRITE, events, maxevents * sizeof(struct epoll_event))) + return -EFAULT; /* Get the "struct file *" for the eventpoll file */ - error = -EBADF; - file = fget(epfd); - if (!file) - goto error_return; + f = fdget(epfd); + if (!f.file) + return -EBADF; /* * We have to check that the file structure underneath the fd * the user passed to us _is_ an eventpoll file. */ error = -EINVAL; - if (!is_file_epoll(file)) + if (!is_file_epoll(f.file)) goto error_fput; /* * At this point it is safe to assume that the "private_data" contains * our own data structure. */ - ep = file->private_data; + ep = f.file->private_data; /* Time to fish for events ... */ error = ep_poll(ep, events, maxevents, timeout); error_fput: - fput(file); -error_return: - DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_wait(%d, %p, %d, %d) = %d\n", - current, epfd, events, maxevents, timeout, error)); - + fdput(f); return error; } -#ifdef TIF_RESTORE_SIGMASK - /* * Implement the event wait interface for the eventpoll file. It is the kernel * part of the user space epoll_pwait(2). */ -asmlinkage long sys_epoll_pwait(int epfd, struct epoll_event __user *events, - int maxevents, int timeout, const sigset_t __user *sigmask, - size_t sigsetsize) +SYSCALL_DEFINE6(epoll_pwait, int, epfd, struct epoll_event __user *, events, + int, maxevents, int, timeout, const sigset_t __user *, sigmask, + size_t, sigsetsize) { int error; sigset_t ksigmask, sigsaved; @@ -1284,8 +2022,8 @@ asmlinkage long sys_epoll_pwait(int epfd, struct epoll_event __user *events, return -EINVAL; if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask))) return -EFAULT; - sigdelsetmask(&ksigmask, sigmask(SIGKILL) | sigmask(SIGSTOP)); - sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved); + sigsaved = current->blocked; + set_current_blocked(&ksigmask); } error = sys_epoll_wait(epfd, events, maxevents, timeout); @@ -1300,34 +2038,98 @@ asmlinkage long sys_epoll_pwait(int epfd, struct epoll_event __user *events, if (error == -EINTR) { memcpy(¤t->saved_sigmask, &sigsaved, sizeof(sigsaved)); - set_thread_flag(TIF_RESTORE_SIGMASK); + set_restore_sigmask(); } else - sigprocmask(SIG_SETMASK, &sigsaved, NULL); + set_current_blocked(&sigsaved); } return error; } -#endif /* #ifdef TIF_RESTORE_SIGMASK */ +#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); + sigsaved = current->blocked; + set_current_blocked(&ksigmask); + } + + 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 + set_current_blocked(&sigsaved); + } + + return err; +} +#endif static int __init eventpoll_init(void) { - mutex_init(&epmutex); + struct sysinfo si; + + si_meminfo(&si); + /* + * Allows top 4% of lomem to be allocated for epoll watches (per user). + */ + max_user_watches = (((si.totalram - si.totalhigh) / 25) << PAGE_SHIFT) / + EP_ITEM_COST; + BUG_ON(max_user_watches < 0); + + /* + * Initialize the structure used to perform epoll file descriptor + * inclusion loops checks. + */ + ep_nested_calls_init(&poll_loop_ncalls); /* Initialize the structure used to perform safe poll wait head wake ups */ - ep_poll_safewake_init(&psw); + 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); + + /* + * 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); /* Allocates slab cache used to allocate "struct epitem" items */ epi_cache = kmem_cache_create("eventpoll_epi", sizeof(struct epitem), - 0, SLAB_HWCACHE_ALIGN|EPI_SLAB_DEBUG|SLAB_PANIC, - NULL); + 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL); /* Allocates slab cache used to allocate "struct eppoll_entry" */ pwq_cache = kmem_cache_create("eventpoll_pwq", - sizeof(struct eppoll_entry), 0, - EPI_SLAB_DEBUG|SLAB_PANIC, NULL); + sizeof(struct eppoll_entry), 0, SLAB_PANIC, NULL); return 0; } fs_initcall(eventpoll_init); - |