1 files changed, 71 insertions, 72 deletions

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index d7f1f5011fac..b041b66002db 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -354,12 +354,6 @@ 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)
 {
@@ -551,28 +545,23 @@ out_unlock:
  */
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 
-static struct nested_calls poll_safewake_ncalls;
-
-static int ep_poll_wakeup_proc(void *priv, void *cookie, int call_nests)
-{
-	unsigned long flags;
-	wait_queue_head_t *wqueue = (wait_queue_head_t *)cookie;
-
-	spin_lock_irqsave_nested(&wqueue->lock, flags, call_nests + 1);
-	wake_up_locked_poll(wqueue, EPOLLIN);
-	spin_unlock_irqrestore(&wqueue->lock, flags);
-
-	return 0;
-}
+static DEFINE_PER_CPU(int, wakeup_nest);
 
 static void ep_poll_safewake(wait_queue_head_t *wq)
 {
-	int this_cpu = get_cpu();
-
-	ep_call_nested(&poll_safewake_ncalls,
-		       ep_poll_wakeup_proc, NULL, wq, (void *) (long) this_cpu);
+	unsigned long flags;
+	int subclass;
 
-	put_cpu();
+	local_irq_save(flags);
+	preempt_disable();
+	subclass = __this_cpu_read(wakeup_nest);
+	spin_lock_nested(&wq->lock, subclass + 1);
+	__this_cpu_inc(wakeup_nest);
+	wake_up_locked_poll(wq, POLLIN);
+	__this_cpu_dec(wakeup_nest);
+	spin_unlock(&wq->lock);
+	local_irq_restore(flags);
+	preempt_enable();
 }
 
 #else
@@ -671,7 +660,6 @@ static __poll_t ep_scan_ready_list(struct eventpoll *ep,
 			      void *priv, int depth, bool ep_locked)
 {
 	__poll_t res;
-	int pwake = 0;
 	struct epitem *epi, *nepi;
 	LIST_HEAD(txlist);
 
@@ -738,26 +726,11 @@ static __poll_t ep_scan_ready_list(struct eventpoll *ep,
 	 */
 	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(&ep->wq);
-		if (waitqueue_active(&ep->poll_wait))
-			pwake++;
-	}
 	write_unlock_irq(&ep->lock);
 
 	if (!ep_locked)
 		mutex_unlock(&ep->mtx);
 
-	/* We have to call this outside the lock */
-	if (pwake)
-		ep_poll_safewake(&ep->poll_wait);
-
 	return res;
 }
 
@@ -1459,13 +1432,13 @@ static int ep_create_wakeup_source(struct epitem *epi)
 	struct wakeup_source *ws;
 
 	if (!epi->ep->ws) {
-		epi->ep->ws = wakeup_source_register("eventpoll");
+		epi->ep->ws = wakeup_source_register(NULL, "eventpoll");
 		if (!epi->ep->ws)
 			return -ENOMEM;
 	}
 
 	name = epi->ffd.file->f_path.dentry->d_name.name;
-	ws = wakeup_source_register(name);
+	ws = wakeup_source_register(NULL, name);
 
 	if (!ws)
 		return -ENOMEM;
@@ -2095,27 +2068,28 @@ SYSCALL_DEFINE1(epoll_create, int, size)
 	return do_epoll_create(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)
+static inline int epoll_mutex_lock(struct mutex *mutex, int depth,
+				   bool nonblock)
+{
+	if (!nonblock) {
+		mutex_lock_nested(mutex, depth);
+		return 0;
+	}
+	if (mutex_trylock(mutex))
+		return 0;
+	return -EAGAIN;
+}
+
+int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds,
+		 bool nonblock)
 {
 	int error;
 	int full_check = 0;
 	struct fd f, tf;
 	struct eventpoll *ep;
 	struct epitem *epi;
-	struct epoll_event epds;
 	struct eventpoll *tep = NULL;
 
-	error = -EFAULT;
-	if (ep_op_has_event(op) &&
-	    copy_from_user(&epds, event, sizeof(struct epoll_event)))
-		goto error_return;
-
 	error = -EBADF;
 	f = fdget(epfd);
 	if (!f.file)
@@ -2133,7 +2107,7 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
 
 	/* Check if EPOLLWAKEUP is allowed */
 	if (ep_op_has_event(op))
-		ep_take_care_of_epollwakeup(&epds);
+		ep_take_care_of_epollwakeup(epds);
 
 	/*
 	 * We have to check that the file structure underneath the file descriptor
@@ -2149,11 +2123,11 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
 	 * so EPOLLEXCLUSIVE is not allowed for a EPOLL_CTL_MOD operation.
 	 * Also, we do not currently supported nested exclusive wakeups.
 	 */
-	if (ep_op_has_event(op) && (epds.events & EPOLLEXCLUSIVE)) {
+	if (ep_op_has_event(op) && (epds->events & EPOLLEXCLUSIVE)) {
 		if (op == EPOLL_CTL_MOD)
 			goto error_tgt_fput;
 		if (op == EPOLL_CTL_ADD && (is_file_epoll(tf.file) ||
-				(epds.events & ~EPOLLEXCLUSIVE_OK_BITS)))
+				(epds->events & ~EPOLLEXCLUSIVE_OK_BITS)))
 			goto error_tgt_fput;
 	}
 
@@ -2178,13 +2152,17 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
 	 * deep wakeup paths from forming in parallel through multiple
 	 * EPOLL_CTL_ADD operations.
 	 */
-	mutex_lock_nested(&ep->mtx, 0);
+	error = epoll_mutex_lock(&ep->mtx, 0, nonblock);
+	if (error)
+		goto error_tgt_fput;
 	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);
+			error = epoll_mutex_lock(&epmutex, 0, nonblock);
+			if (error)
+				goto error_tgt_fput;
+			full_check = 1;
 			if (is_file_epoll(tf.file)) {
 				error = -ELOOP;
 				if (ep_loop_check(ep, tf.file) != 0) {
@@ -2194,10 +2172,19 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
 			} else
 				list_add(&tf.file->f_tfile_llink,
 							&tfile_check_list);
-			mutex_lock_nested(&ep->mtx, 0);
+			error = epoll_mutex_lock(&ep->mtx, 0, nonblock);
+			if (error) {
+out_del:
+				list_del(&tf.file->f_tfile_llink);
+				goto error_tgt_fput;
+			}
 			if (is_file_epoll(tf.file)) {
 				tep = tf.file->private_data;
-				mutex_lock_nested(&tep->mtx, 1);
+				error = epoll_mutex_lock(&tep->mtx, 1, nonblock);
+				if (error) {
+					mutex_unlock(&ep->mtx);
+					goto out_del;
+				}
 			}
 		}
 	}
@@ -2213,8 +2200,8 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
 	switch (op) {
 	case EPOLL_CTL_ADD:
 		if (!epi) {
-			epds.events |= EPOLLERR | EPOLLHUP;
-			error = ep_insert(ep, &epds, tf.file, fd, full_check);
+			epds->events |= EPOLLERR | EPOLLHUP;
+			error = ep_insert(ep, epds, tf.file, fd, full_check);
 		} else
 			error = -EEXIST;
 		if (full_check)
@@ -2229,8 +2216,8 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
 	case EPOLL_CTL_MOD:
 		if (epi) {
 			if (!(epi->event.events & EPOLLEXCLUSIVE)) {
-				epds.events |= EPOLLERR | EPOLLHUP;
-				error = ep_modify(ep, epi, &epds);
+				epds->events |= EPOLLERR | EPOLLHUP;
+				error = ep_modify(ep, epi, epds);
 			}
 		} else
 			error = -ENOENT;
@@ -2253,6 +2240,23 @@ error_return:
 }
 
 /*
+ * 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)
+{
+	struct epoll_event epds;
+
+	if (ep_op_has_event(op) &&
+	    copy_from_user(&epds, event, sizeof(struct epoll_event)))
+		return -EFAULT;
+
+	return do_epoll_ctl(epfd, op, fd, &epds, false);
+}
+
+/*
  * Implement the event wait interface for the eventpoll file. It is the kernel
  * part of the user space epoll_wait(2).
  */
@@ -2370,11 +2374,6 @@ static int __init eventpoll_init(void)
 	 */
 	ep_nested_calls_init(&poll_loop_ncalls);
 
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-	/* Initialize the structure used to perform safe poll wait head wake ups */
-	ep_nested_calls_init(&poll_safewake_ncalls);
-#endif
-
 	/*
 	 * We can have many thousands of epitems, so prevent this from
 	 * using an extra cache line on 64-bit (and smaller) CPUs