cregit-Linux how code gets into the kernel

Release 4.11 fs/eventpoll.c

Directory: fs
 *  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
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *  Davide Libenzi <>

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/sched/signal.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>
#include <linux/string.h>
#include <linux/list.h>
#include <linux/hash.h>
#include <linux/spinlock.h>
#include <linux/syscalls.h>
#include <linux/rbtree.h>
#include <linux/wait.h>
#include <linux/eventpoll.h>
#include <linux/mount.h>
#include <linux/bitops.h>
#include <linux/mutex.h>
#include <linux/anon_inodes.h>
#include <linux/device.h>
#include <linux/uaccess.h>
#include <asm/io.h>
#include <asm/mman.h>
#include <linux/atomic.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/compat.h>
#include <linux/rculist.h>

 * There are three level of locking required by epoll :
 * 1) epmutex (mutex)
 * 2) ep->mtx (mutex)
 * 3) ep->lock (spinlock)
 * 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
 * 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
 * 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 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.
 * Events that require holding "epmutex" are very rare, while for
 * normal operations the epoll private "ep->mtx" will guarantee
 * a better scalability.

/* Epoll private bits inside the event mask */



                                EPOLLWAKEUP | EPOLLET | EPOLLEXCLUSIVE)

/* 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;

 * Structure used to track possible nested calls, for too deep recursions
 * and loop cycles.

struct nested_call_node {
struct list_head llink;
void *cookie;
void *ctx;

 * This structure is used as collector for nested calls, to check for
 * maximum recursion dept and loop cycles.

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 {
	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;

         * Works together "struct eventpoll"->ovflist in keeping the
         * single linked chain of items.
struct epitem *next;

	/* 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;

	/* 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 represents the main data structure for the eventpoll
 * interface.

struct eventpoll {
	/* Protect the access to this structure */
spinlock_t lock;

         * 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.
struct mutex mtx;

	/* 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;

	/* RB tree root used to store monitored fd structs */
struct rb_root rbr;

         * This is a single linked list that chains all the "struct epitem" that
         * 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 */

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" */
struct epitem *base;

         * 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;

/* Wrapper struct used by poll queueing */

struct ep_pqueue {
poll_table pt;
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 DEFINE_MUTEX(epmutex);

/* Used to check for epoll file descriptor inclusion loops */

static struct nested_calls poll_loop_ncalls;

/* 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;

/* 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);


#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; }


Jason Baron20100.00%1100.00%

/* Setup the structure that is used as key for the RB tree */
static inline void ep_set_ffd(struct epoll_filefd *ffd, struct file *file, int fd) { ffd->file = file; ffd->fd = fd; }


Davide Libenzi2990.62%375.00%
Andrew Morton39.38%125.00%

/* Compare RB tree keys */
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)); }


Davide Libenzi52100.00%2100.00%

/* Tells us if the item is currently linked */
static inline int ep_is_linked(struct list_head *p) { return !list_empty(p); }


Davide Libenzi19100.00%3100.00%

static inline struct eppoll_entry *ep_pwq_from_wait(wait_queue_t *p) { return container_of(p, struct eppoll_entry, wait); }


Oleg Nesterov24100.00%1100.00%

/* Get the "struct epitem" from a wait queue pointer */
static inline struct epitem *ep_item_from_wait(wait_queue_t *p) { return container_of(p, struct eppoll_entry, wait)->base; }


Davide Libenzi26100.00%4100.00%

/* Get the "struct epitem" from an epoll queue wrapper */
static inline struct epitem *ep_item_from_epqueue(poll_table *p) { return container_of(p, struct ep_pqueue, pt)->epi; }


Davide Libenzi26100.00%4100.00%

/* Tells if the epoll_ctl(2) operation needs an event copy from userspace */
static inline int ep_op_has_event(int op) { return op != EPOLL_CTL_DEL; }


Davide Libenzi1386.67%375.00%
Andrew Morton213.33%125.00%

/* Initialize the poll safe wake up structure */
static void ep_nested_calls_init(struct nested_calls *ncalls) { INIT_LIST_HEAD(&ncalls->tasks_call_list); spin_lock_init(&ncalls->lock); }


Davide Libenzi27100.00%3100.00%

/** * 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; }


Davide Libenzi28100.00%1100.00%

/** * 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 int ep_call_nested(struct nested_calls *ncalls, int max_nests, int (*nproc)(void *, void *, int), void *priv, void *cookie, void *ctx) { int error, call_nests = 0; unsigned long flags; struct list_head *lsthead = &ncalls->tasks_call_list; struct nested_call_node *tncur; struct nested_call_node tnode; spin_lock_irqsave(&ncalls->lock, flags); /* * 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->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. */ error = -1; goto out_unlock; } } /* Add the current task and cookie to the list */ tnode.ctx = ctx; tnode.cookie = cookie; list_add(&tnode.llink, lsthead); spin_unlock_irqrestore(&ncalls->lock, flags); /* Call the nested function */ error = (*nproc)(priv, cookie, call_nests); /* Remove the current task from the list */ spin_lock_irqsave(&ncalls->lock, flags); list_del(&tnode.llink); out_unlock: spin_unlock_irqrestore(&ncalls->lock, flags); return error; }


Davide Libenzi19393.69%975.00%
Tony Battersby83.88%18.33%
Matthias Kaehlcke41.94%18.33%
Peter Zijlstra10.49%18.33%

/* * 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); }


Davide Libenzi51100.00%1100.00%

static inline void ep_wake_up_nested(wait_queue_head_t *wqueue, unsigned long events, int subclass) { wake_up_poll(wqueue, events); }


Davide Libenzi25100.00%1100.00%

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; }


Davide Libenzi35100.00%2100.00%

/* * 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(); }


Davide Libenzi42100.00%3100.00%

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(); }


Oleg Nesterov45100.00%1100.00%

/* * 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) { struct list_head *lsthead = &epi->pwqlist; struct eppoll_entry *pwq; 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); } }


Davide Libenzi6994.52%457.14%
Andrew Morton22.74%114.29%
Oleg Nesterov11.37%114.29%
Tony Battersby11.37%114.29%

/* 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)); }


Eric Wong32100.00%1100.00%

/* 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); }


Eric Wong31100.00%1100.00%

static inline bool ep_has_wakeup_source(struct epitem *epi) { return rcu_access_pointer(epi->ws) ? true : false; }


Eric Wong24100.00%1100.00%

/* 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(); }


Eric Wong41100.00%1100.00%

/** * 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); /* * 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. */ 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; }


Davide Libenzi28188.92%1368.42%
Jason Baron134.11%15.26%
Arve Hjönnevåg134.11%15.26%
Nelson Elhage61.90%15.26%
Tony Battersby10.32%15.26%
Andrew Morton10.32%15.26%
Eric Wong10.32%15.26%

static void epi_rcu_free(struct rcu_head *head) { struct epitem *epi = container_of(head, struct epitem, rcu); kmem_cache_free(epi_cache, epi); }


Jason Baron33100.00%1100.00%

/* * Removes a "struct epitem" from the eventpoll RB tree and deallocates * all the associated resources. Must be called with "mtx" held. */
static int ep_remove(struct eventpoll *ep, struct epitem *epi) { unsigned long flags; struct file *file = epi->ffd.file; /* * 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". */ ep_unregister_pollwait(ep, epi); /* Remove the current item from the list of epoll hooks */ spin_lock(&file->f_lock); list_del_rcu(&epi->fllink); spin_unlock(&file->f_lock); 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); 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); atomic_long_dec(&ep->user->epoll_watches); return 0; }


Davide Libenzi12484.35%550.00%
Jason Baron85.44%110.00%
Andrew Morton64.08%110.00%
Arve Hjönnevåg53.40%110.00%
Eric Wong32.04%110.00%
Robin Holt10.68%110.00%

static void ep_free(struct eventpoll *ep) { struct rb_node *rbp; struct epitem *epi; /* We need to release all tasks waiting for these file */ if (waitqueue_active(&ep->poll_wait)) ep_poll_safewake(&ep->poll_wait); /* * We need to lock this because we could be hit by * eventpoll_release_file() while we're freeing the "struct eventpoll". * 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 sufficient here. */ mutex_lock(&epmutex); /* * Walks through the whole tree by unregistering poll callbacks. */ for (rbp = rb_first(&ep->rbr); rbp; rbp = rb_next(rbp)) { epi = rb_entry(rbp, struct epitem, rbn); ep_unregister_pollwait(ep, epi); cond_resched(); } /* * 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 * 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); }


Davide Libenzi14679.78%758.33%
Eric Wong179.29%18.33%
Arve Hjönnevåg73.83%18.33%
Eric Dumazet63.28%18.33%
Andrew Morton63.28%18.33%
Lucas De Marchi10.55%18.33%

static int ep_eventpoll_release(struct inode *inode, struct file *file) { struct eventpoll *ep = file->private_data; if (ep) ep_free(ep); return 0; }


Davide Libenzi3697.30%583.33%
Jesper Juhl12.70%116.67%

static inline unsigned int ep_item_poll(struct epitem *epi, poll_table *pt) { pt->_key = epi->; return epi->ffd.file->f_op->poll(epi->ffd.file, pt) & epi->; }


Eric Wong53100.00%1100.00%

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; }


Davide Libenzi6775.28%660.00%
Hans Verkuil1314.61%110.00%
Arve Hjönnevåg55.62%110.00%
Eric Wong44.49%220.00%

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); }


Davide Libenzi2659.09%466.67%
Jason Baron1431.82%116.67%
Nelson Elhage49.09%116.67%

static unsigned int ep_eventpoll_poll(struct file *file, poll_table *wait) { 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); /* * 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; }


Davide Libenzi6971.88%787.50%
Jason Baron2728.12%112.50%

static void ep_show_fdinfo(struct seq_file *m, struct file *f) { struct eventpoll *ep = f->private_data; struct rb_node *rbp; mutex_lock(&ep->mtx); for (rbp = rb_first(&ep->rbr); rbp; rbp = rb_next(rbp)) { struct epitem *epi = rb_entry(rbp, struct epitem, rbn); seq_printf(m, "tfd: %8d events: %8x data: %16llx\n", epi->ffd.fd, epi->, (long long)epi->; if (seq_has_overflowed(m)) break; } mutex_unlock(&ep->mtx); }


Cyrill V. Gorcunov11695.87%150.00%
Joe Perches54.13%150.00%

#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, .llseek = noop_llseek, }; /* * 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. */
void eventpoll_release_file(struct file *file) { struct eventpoll *ep; struct epitem *epi, *next; /* * 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 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); list_for_each_entry_safe(epi, next, &file->f_ep_links, fllink) { ep = epi->ep; mutex_lock_nested(&ep->mtx, 0); ep_remove(ep, epi); mutex_unlock(&ep->mtx); } mutex_unlock(&epmutex); }


Davide Libenzi6582.28%660.00%
Konstantin Khlebnikov67.59%110.00%
Jason Baron45.06%110.00%
Nelson Elhage33.80%110.00%
Lucas De Marchi11.27%110.00%

static int ep_alloc(struct eventpoll **pep) { int error; struct user_struct *user; struct eventpoll *ep; 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); init_waitqueue_head(&ep->wq); init_waitqueue_head(&ep->poll_wait); INIT_LIST_HEAD(&ep->rdllist); ep->rbr = RB_ROOT; ep->ovflist = EP_UNACTIVE_PTR; ep->user = user; *pep = ep; return 0; free_uid: free_uid(user); return error; }


Davide Libenzi135100.00%8100.00%

/* * 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. */
static struct epitem *ep_find(struct eventpoll *ep, struct file *file, int fd) { int kcmp; struct rb_node *rbp; struct epitem *epi, *epir = NULL; struct epoll_filefd ffd; ep_set_ffd(&ffd, file, fd); for (rbp = ep->rbr.rb_node; rbp; ) { epi = rb_entry(rbp, struct epitem, rbn); kcmp = ep_cmp_ffd(&ffd, &epi->ffd); if (kcmp > 0) rbp = rbp->rb_right; else if (kcmp < 0) rbp = rbp->rb_left; else { epir = epi; break; } } return epir