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diff --git a/ANDROID_3.4.5/fs/eventpoll.c b/ANDROID_3.4.5/fs/eventpoll.c
deleted file mode 100644
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--- a/ANDROID_3.4.5/fs/eventpoll.c
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@@ -1,1938 +0,0 @@
-/*
- * 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 <davidel@xmailserver.org>
- *
- */
-
-#include <linux/init.h>
-#include <linux/kernel.h>
-#include <linux/sched.h>
-#include <linux/fs.h>
-#include <linux/file.h>
-#include <linux/signal.h>
-#include <linux/errno.h>
-#include <linux/mm.h>
-#include <linux/slab.h>
-#include <linux/poll.h>
-#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 <asm/uaccess.h>
-#include <asm/io.h>
-#include <asm/mman.h>
-#include <linux/atomic.h>
-
-/*
- * LOCKING:
- * 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 */
-#define EP_PRIVATE_BITS (EPOLLWAKEUP | EPOLLONESHOT | EPOLLET)
-
-/* 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.
- */
-struct epitem {
- /* RB tree node used to link this structure to the eventpoll RB tree */
- struct rb_node rbn;
-
- /* 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 *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);
-
-#ifdef CONFIG_SYSCTL
-
-#include <linux/sysctl.h>
-
-static long zero;
-static long long_max = LONG_MAX;
-
-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,
- struct file *file, int fd)
-{
- ffd->file = file;
- ffd->fd = fd;
-}
-
-/* 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));
-}
-
-/* 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)
-{
- 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)
-{
- return container_of(p, struct ep_pqueue, pt)->epi;
-}
-
-/* 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;
-}
-
-/* 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);
-}
-
-/**
- * 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;
-}
-
-/**
- * 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;
-}
-
-/*
- * 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)
-{
- 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);
- }
-}
-
-/**
- * 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.
- *
- * 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)
-{
- 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().
- */
- 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);
- __pm_stay_awake(epi->ws);
- }
- }
- /*
- * 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);
-
- mutex_unlock(&ep->mtx);
-
- /* We have to call this outside the lock */
- if (pwake)
- ep_poll_safewake(&ep->poll_wait);
-
- return error;
-}
-
-/*
- * 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);
- if (ep_is_linked(&epi->fllink))
- list_del_init(&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(epi->ws);
-
- /* At this point it is safe to free the eventpoll item */
- kmem_cache_free(epi_cache, epi);
-
- atomic_long_dec(&ep->user->epoll_watches);
-
- return 0;
-}
-
-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);
- }
-
- /*
- * 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".
- */
- while ((rbp = rb_first(&ep->rbr)) != NULL) {
- epi = rb_entry(rbp, struct epitem, rbn);
- ep_remove(ep, epi);
- }
-
- mutex_unlock(&epmutex);
- mutex_destroy(&ep->mtx);
- free_uid(ep->user);
- wakeup_source_unregister(ep->ws);
- kfree(ep);
-}
-
-static int ep_eventpoll_release(struct inode *inode, struct file *file)
-{
- struct eventpoll *ep = file->private_data;
-
- if (ep)
- ep_free(ep);
-
- return 0;
-}
-
-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) {
- pt._key = epi->event.events;
- if (epi->ffd.file->f_op->poll(epi->ffd.file, &pt) &
- epi->event.events)
- 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(epi->ws);
- list_del_init(&epi->rdllink);
- }
- }
-
- return 0;
-}
-
-static int ep_poll_readyevents_proc(void *priv, void *cookie, int call_nests)
-{
- return ep_scan_ready_list(priv, ep_read_events_proc, NULL, call_nests + 1);
-}
-
-static unsigned int ep_eventpoll_poll(struct file *file, poll_table *wait)
-{
- int pollflags;
- struct eventpoll *ep = file->private_data;
-
- /* 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, ep, ep, current);
-
- return pollflags != -1 ? pollflags : 0;
-}
-
-/* File callbacks that implement the eventpoll file behaviour */
-static const struct file_operations eventpoll_fops = {
- .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 list_head *lsthead = &file->f_ep_links;
- struct eventpoll *ep;
- struct epitem *epi;
-
- /*
- * 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);
-
- while (!list_empty(lsthead)) {
- epi = list_first_entry(lsthead, struct epitem, fllink);
-
- ep = epi->ep;
- list_del_init(&epi->fllink);
- mutex_lock_nested(&ep->mtx, 0);
- ep_remove(ep, epi);
- mutex_unlock(&ep->mtx);
- }
-
- mutex_unlock(&epmutex);
-}
-
-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;
-}
-
-/*
- * 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;
-}
-
-/*
- * This is the callback that is passed to the wait queue wakeup
- * 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)
-{
- int pwake = 0;
- unsigned long flags;
- struct epitem *epi = ep_item_from_wait(wait);
- struct eventpoll *ep = 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);
-
- /*
- * If the event mask does not contain any poll(2) event, we consider the
- * descriptor to be disabled. This condition is likely the effect of the
- * EPOLLONESHOT bit that disables the descriptor when an event is received,
- * until the next EPOLL_CTL_MOD will be issued.
- */
- if (!(epi->event.events & ~EP_PRIVATE_BITS))
- goto out_unlock;
-
- /*
- * 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 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)) {
- list_add_tail(&epi->rdllink, &ep->rdllist);
- __pm_stay_awake(epi->ws);
- }
-
- /*
- * Wake up ( if active ) both the eventpoll wait list and the ->poll()
- * wait list.
- */
- if (waitqueue_active(&ep->wq))
- wake_up_locked(&ep->wq);
- if (waitqueue_active(&ep->poll_wait))
- pwake++;
-
-out_unlock:
- spin_unlock_irqrestore(&ep->lock, flags);
-
- /* We have to call this outside the lock */
- if (pwake)
- ep_poll_safewake(&ep->poll_wait);
-
- return 1;
-}
-
-/*
- * This is the callback that is used to add our wait queue to the
- * target file wakeup lists.
- */
-static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead,
- poll_table *pt)
-{
- struct epitem *epi = ep_item_from_epqueue(pt);
- struct eppoll_entry *pwq;
-
- if (epi->nwait >= 0 && (pwq = kmem_cache_alloc(pwq_cache, GFP_KERNEL))) {
- init_waitqueue_func_entry(&pwq->wait, ep_poll_callback);
- pwq->whead = whead;
- pwq->base = epi;
- add_wait_queue(whead, &pwq->wait);
- list_add_tail(&pwq->llink, &epi->pwqlist);
- epi->nwait++;
- } else {
- /* We have to signal that an error occurred */
- epi->nwait = -1;
- }
-}
-
-static void ep_rbtree_insert(struct eventpoll *ep, struct epitem *epi)
-{
- int kcmp;
- struct rb_node **p = &ep->rbr.rb_node, *parent = NULL;
- struct epitem *epic;
-
- while (*p) {
- parent = *p;
- epic = rb_entry(parent, struct epitem, rbn);
- kcmp = ep_cmp_ffd(&epi->ffd, &epic->ffd);
- if (kcmp > 0)
- p = &parent->rb_right;
- else
- p = &parent->rb_left;
- }
- rb_link_node(&epi->rbn, parent, p);
- rb_insert_color(&epi->rbn, &ep->rbr);
-}
-
-
-
-#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;
-
- list_for_each_entry(epi, &file->f_ep_links, fllink) {
- child_file = epi->ep->file;
- if (is_file_epoll(child_file)) {
- if (list_empty(&child_file->f_ep_links)) {
- if (path_count_inc(call_nests)) {
- error = -1;
- break;
- }
- } else {
- error = ep_call_nested(&poll_loop_ncalls,
- EP_MAX_NESTS,
- reverse_path_check_proc,
- child_file, child_file,
- current);
- }
- if (error != 0)
- break;
- } else {
- printk(KERN_ERR "reverse_path_check_proc: "
- "file is not an ep!\n");
- }
- }
- 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;
-
- 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;
- epi->ws = wakeup_source_register(name);
- if (!epi->ws)
- return -ENOMEM;
-
- return 0;
-}
-
-static void ep_destroy_wakeup_source(struct epitem *epi)
-{
- wakeup_source_unregister(epi->ws);
- epi->ws = NULL;
-}
-
-/*
- * Must be called with "mtx" held.
- */
-static int ep_insert(struct eventpoll *ep, struct epoll_event *event,
- struct file *tfile, int fd)
-{
- int error, revents, pwake = 0;
- unsigned long flags;
- long user_watches;
- struct epitem *epi;
- struct ep_pqueue epq;
-
- 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)))
- return -ENOMEM;
-
- /* Item initialization follow here ... */
- INIT_LIST_HEAD(&epi->rdllink);
- INIT_LIST_HEAD(&epi->fllink);
- INIT_LIST_HEAD(&epi->pwqlist);
- epi->ep = ep;
- ep_set_ffd(&epi->ffd, tfile, fd);
- 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 {
- epi->ws = NULL;
- }
-
- /* Initialize the poll table using the queue callback */
- epq.epi = epi;
- init_poll_funcptr(&epq.pt, ep_ptable_queue_proc);
- epq.pt._key = event->events;
-
- /*
- * Attach the item to the poll hooks and get current event bits.
- * We can safely use the file* here because its usage count has
- * been increased by the caller of this function. Note that after
- * this operation completes, the poll callback can start hitting
- * the new item.
- */
- revents = tfile->f_op->poll(tfile, &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_lock);
- list_add_tail(&epi->fllink, &tfile->f_ep_links);
- spin_unlock(&tfile->f_lock);
-
- /*
- * Add the current item to the RB tree. All RB tree operations are
- * protected by "mtx", and ep_insert() is called with "mtx" held.
- */
- ep_rbtree_insert(ep, epi);
-
- /* now check if we've created too many backpaths */
- error = -EINVAL;
- if (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);
- __pm_stay_awake(epi->ws);
-
- /* Notify waiting tasks that events are available */
- if (waitqueue_active(&ep->wq))
- wake_up_locked(&ep->wq);
- if (waitqueue_active(&ep->poll_wait))
- pwake++;
- }
-
- 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(&ep->poll_wait);
-
- return 0;
-
-error_remove_epi:
- spin_lock(&tfile->f_lock);
- if (ep_is_linked(&epi->fllink))
- list_del_init(&epi->fllink);
- spin_unlock(&tfile->f_lock);
-
- rb_erase(&epi->rbn, &ep->rbr);
-
-error_unregister:
- ep_unregister_pollwait(ep, epi);
-
- /*
- * We need to do this because an event could have been arrived on some
- * allocated wait queue. Note that we don't care about the ep->ovflist
- * list, since that is used/cleaned only inside a section bound by "mtx".
- * And ep_insert() is called with "mtx" held.
- */
- 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(epi->ws);
-
-error_create_wakeup_source:
- kmem_cache_free(epi_cache, epi);
-
- return error;
-}
-
-/*
- * Modify the interest event mask by dropping an event if the new mask
- * has a match in the current file status. Must be called with "mtx" held.
- */
-static int ep_modify(struct eventpoll *ep, struct epitem *epi, struct epoll_event *event)
-{
- int pwake = 0;
- unsigned int revents;
- 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;
- pt._key = event->events;
- epi->event.data = event->data; /* protected by mtx */
- if (epi->event.events & EPOLLWAKEUP) {
- if (!epi->ws)
- ep_create_wakeup_source(epi);
- } else if (epi->ws) {
- ep_destroy_wakeup_source(epi);
- }
-
- /*
- * 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, &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);
- __pm_stay_awake(epi->ws);
-
- /* Notify waiting tasks that events are available */
- if (waitqueue_active(&ep->wq))
- wake_up_locked(&ep->wq);
- if (waitqueue_active(&ep->poll_wait))
- pwake++;
- }
- spin_unlock_irq(&ep->lock);
- }
-
- /* We have to call this outside the lock */
- if (pwake)
- ep_poll_safewake(&ep->poll_wait);
-
- return 0;
-}
-
-static int ep_send_events_proc(struct eventpoll *ep, struct list_head *head,
- void *priv)
-{
- struct ep_send_events_data *esed = priv;
- int eventcnt;
- unsigned int revents;
- struct epitem *epi;
- struct epoll_event __user *uevent;
- poll_table pt;
-
- init_poll_funcptr(&pt, NULL);
-
- /*
- * 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.
- */
- for (eventcnt = 0, uevent = esed->events;
- !list_empty(head) && eventcnt < esed->maxevents;) {
- epi = list_first_entry(head, 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().
- */
- if (epi->ws && epi->ws->active)
- __pm_stay_awake(ep->ws);
- __pm_relax(epi->ws);
- list_del_init(&epi->rdllink);
-
- pt._key = epi->event.events;
- revents = epi->ffd.file->f_op->poll(epi->ffd.file, &pt) &
- epi->event.events;
-
- /*
- * 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, &uevent->events) ||
- __put_user(epi->event.data, &uevent->data)) {
- list_add(&epi->rdllink, head);
- __pm_stay_awake(epi->ws);
- return eventcnt ? eventcnt : -EFAULT;
- }
- eventcnt++;
- uevent++;
- if (epi->event.events & EPOLLONESHOT)
- epi->event.events &= EP_PRIVATE_BITS;
- else if (!(epi->event.events & EPOLLET)) {
- /*
- * If this file has been added with Level
- * Trigger mode, we need to insert back inside
- * the ready list, so that the next call to
- * epoll_wait() will check again the events
- * 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);
- __pm_stay_awake(epi->ws);
- }
- }
- }
-
- return eventcnt;
-}
-
-static int ep_send_events(struct eventpoll *ep,
- struct epoll_event __user *events, int maxevents)
-{
- struct ep_send_events_data esed;
-
- esed.maxevents = maxevents;
- esed.events = events;
-
- return ep_scan_ready_list(ep, ep_send_events_proc, &esed, 0);
-}
-
-static inline struct timespec ep_set_mstimeout(long ms)
-{
- struct timespec now, ts = {
- .tv_sec = ms / MSEC_PER_SEC,
- .tv_nsec = NSEC_PER_MSEC * (ms % MSEC_PER_SEC),
- };
-
- ktime_get_ts(&now);
- return timespec_add_safe(now, ts);
-}
-
-/**
- * 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 = 0, eavail, timed_out = 0;
- unsigned long flags;
- long slack = 0;
- wait_queue_t wait;
- ktime_t expires, *to = NULL;
-
- 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;
- }
-
-fetch_events:
- spin_lock_irqsave(&ep->lock, flags);
-
- 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);
- __add_wait_queue_exclusive(&ep->wq, &wait);
-
- for (;;) {
- /*
- * We don't want to sleep if the ep_poll_callback() sends us
- * a wakeup in between. That's why we set the task state
- * to TASK_INTERRUPTIBLE before doing the checks.
- */
- set_current_state(TASK_INTERRUPTIBLE);
- if (ep_events_available(ep) || timed_out)
- break;
- if (signal_pending(current)) {
- res = -EINTR;
- break;
- }
-
- spin_unlock_irqrestore(&ep->lock, flags);
- 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 = ep_events_available(ep);
-
- spin_unlock_irqrestore(&ep->lock, flags);
-
- /*
- * Try to transfer events to user space. In case we get 0 events and
- * there's still timeout left over, we go trying again in search of
- * more luck.
- */
- if (!res && eavail &&
- !(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);
-}
-
-/*
- * Open an eventpoll file descriptor.
- */
-SYSCALL_DEFINE1(epoll_create1, int, flags)
-{
- int error, fd;
- struct eventpoll *ep = NULL;
- struct file *file;
-
- /* Check the EPOLL_* constant for consistency. */
- BUILD_BUG_ON(EPOLL_CLOEXEC != O_CLOEXEC);
-
- if (flags & ~EPOLL_CLOEXEC)
- return -EINVAL;
- /*
- * Create the internal data structure ("struct eventpoll").
- */
- 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 a free file descriptor.
- */
- 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;
- }
- fd_install(fd, file);
- ep->file = file;
- return fd;
-
-out_free_fd:
- put_unused_fd(fd);
-out_free_ep:
- ep_free(ep);
- 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.
- */
-SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
- struct epoll_event __user *, event)
-{
- int error;
- int did_lock_epmutex = 0;
- struct file *file, *tfile;
- struct eventpoll *ep;
- struct epitem *epi;
- struct epoll_event epds;
-
- 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)
- goto error_return;
-
- /* Get the "struct file *" for the target file */
- tfile = fget(fd);
- if (!tfile)
- goto error_fput;
-
- /* The target file descriptor must support poll */
- error = -EPERM;
- if (!tfile->f_op || !tfile->f_op->poll)
- goto error_tgt_fput;
-
- /* Check if EPOLLWAKEUP is allowed */
- if ((epds.events & EPOLLWAKEUP) && !capable(CAP_EPOLLWAKEUP))
- epds.events &= ~EPOLLWAKEUP;
-
- /*
- * 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))
- 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;
-
- /*
- * 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 need to hold the epmutex across both ep_insert and ep_remove
- * b/c we want to make sure we are looking at a coherent view of
- * epoll network.
- */
- if (op == EPOLL_CTL_ADD || op == EPOLL_CTL_DEL) {
- mutex_lock(&epmutex);
- did_lock_epmutex = 1;
- }
- if (op == EPOLL_CTL_ADD) {
- if (is_file_epoll(tfile)) {
- error = -ELOOP;
- if (ep_loop_check(ep, tfile) != 0) {
- clear_tfile_check_list();
- goto error_tgt_fput;
- }
- } else
- list_add(&tfile->f_tfile_llink, &tfile_check_list);
- }
-
- mutex_lock_nested(&ep->mtx, 0);
-
- /*
- * 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);
-
- error = -EINVAL;
- switch (op) {
- case EPOLL_CTL_ADD:
- if (!epi) {
- epds.events |= POLLERR | POLLHUP;
- error = ep_insert(ep, &epds, tfile, fd);
- } else
- error = -EEXIST;
- clear_tfile_check_list();
- break;
- case EPOLL_CTL_DEL:
- if (epi)
- error = ep_remove(ep, epi);
- else
- error = -ENOENT;
- break;
- case EPOLL_CTL_MOD:
- if (epi) {
- epds.events |= POLLERR | POLLHUP;
- error = ep_modify(ep, epi, &epds);
- } else
- error = -ENOENT;
- break;
- }
- mutex_unlock(&ep->mtx);
-
-error_tgt_fput:
- if (did_lock_epmutex)
- mutex_unlock(&epmutex);
-
- fput(tfile);
-error_fput:
- fput(file);
-error_return:
-
- return error;
-}
-
-/*
- * Implement the event wait interface for the eventpoll file. It is the kernel
- * part of the user space epoll_wait(2).
- */
-SYSCALL_DEFINE4(epoll_wait, int, epfd, struct epoll_event __user *, events,
- int, maxevents, int, timeout)
-{
- int error;
- struct file *file;
- struct eventpoll *ep;
-
- /* 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;
- }
-
- /* Get the "struct file *" for the eventpoll file */
- error = -EBADF;
- file = fget(epfd);
- if (!file)
- goto error_return;
-
- /*
- * 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))
- goto error_fput;
-
- /*
- * At this point it is safe to assume that the "private_data" contains
- * our own data structure.
- */
- ep = file->private_data;
-
- /* Time to fish for events ... */
- error = ep_poll(ep, events, maxevents, timeout);
-
-error_fput:
- fput(file);
-error_return:
-
- return error;
-}
-
-#ifdef HAVE_SET_RESTORE_SIGMASK
-
-/*
- * Implement the event wait interface for the eventpoll file. It is the kernel
- * part of the user space epoll_pwait(2).
- */
-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;
-
- /*
- * If the caller wants a certain signal mask to be set during the wait,
- * we apply it here.
- */
- if (sigmask) {
- if (sigsetsize != sizeof(sigset_t))
- return -EINVAL;
- if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask)))
- return -EFAULT;
- sigdelsetmask(&ksigmask, sigmask(SIGKILL) | sigmask(SIGSTOP));
- sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
- }
-
- error = sys_epoll_wait(epfd, events, maxevents, timeout);
-
- /*
- * If we changed the signal mask, we need to restore the original one.
- * In case we've got a signal while waiting, we do not restore the
- * signal mask yet, and we allow do_signal() to deliver the signal on
- * the way back to userspace, before the signal mask is restored.
- */
- if (sigmask) {
- if (error == -EINTR) {
- memcpy(&current->saved_sigmask, &sigsaved,
- sizeof(sigsaved));
- set_restore_sigmask();
- } else
- sigprocmask(SIG_SETMASK, &sigsaved, NULL);
- }
-
- return error;
-}
-
-#endif /* HAVE_SET_RESTORE_SIGMASK */
-
-static int __init eventpoll_init(void)
-{
- 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_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);
-
- /* Allocates slab cache used to allocate "struct epitem" items */
- epi_cache = kmem_cache_create("eventpoll_epi", sizeof(struct epitem),
- 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, SLAB_PANIC, NULL);
-
- return 0;
-}
-fs_initcall(eventpoll_init);
generated by cgit (git 2.34.1) at 2024-12-20 13:53:03 +0000