Merge branch 'akpm' (Andrew's patch-bomb)

Merge second batch of patches from Andrew Morton:
 - various misc things
 - core kernel changes to prctl, exit, exec, init, etc.
 - kernel/watchdog.c updates
 - get_maintainer
 - MAINTAINERS
 - the backlight driver queue
 - core bitops code cleanups
 - the led driver queue
 - some core prio_tree work
 - checkpatch udpates
 - largeish crc32 update
 - a new poll() feature for the v4l guys
 - the rtc driver queue
 - fatfs
 - ptrace
 - signals
 - kmod/usermodehelper updates
 - coredump
 - procfs updates

* emailed from Andrew Morton <akpm@linux-foundation.org>: (141 commits)
  seq_file: add seq_set_overflow(), seq_overflow()
  proc-ns: use d_set_d_op() API to set dentry ops in proc_ns_instantiate().
  procfs: speed up /proc/pid/stat, statm
  procfs: add num_to_str() to speed up /proc/stat
  proc: speed up /proc/stat handling
  fs/proc/kcore.c: make get_sparsemem_vmemmap_info() static
  coredump: add VM_NODUMP, MADV_NODUMP, MADV_CLEAR_NODUMP
  coredump: remove VM_ALWAYSDUMP flag
  kmod: make __request_module() killable
  kmod: introduce call_modprobe() helper
  usermodehelper: ____call_usermodehelper() doesn't need do_exit()
  usermodehelper: kill umh_wait, renumber UMH_* constants
  usermodehelper: implement UMH_KILLABLE
  usermodehelper: introduce umh_complete(sub_info)
  usermodehelper: use UMH_WAIT_PROC consistently
  signal: zap_pid_ns_processes: s/SEND_SIG_NOINFO/SEND_SIG_FORCED/
  signal: oom_kill_task: use SEND_SIG_FORCED instead of force_sig()
  signal: cosmetic, s/from_ancestor_ns/force/ in prepare_signal() paths
  signal: give SEND_SIG_FORCED more power to beat SIGNAL_UNKILLABLE
  Hexagon: use set_current_blocked() and block_sigmask()
  ...

1 files changed, 40 insertions, 5 deletions

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 4d9d3a45e356..629e9ed99d0f 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -427,6 +427,31 @@ out_unlock:
 	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)
@@ -699,9 +724,12 @@ 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 (epi->ffd.file->f_op->poll(epi->ffd.file, NULL) &
+		pt._key = epi->event.events;
+		if (epi->ffd.file->f_op->poll(epi->ffd.file, &pt) &
 		    epi->event.events)
 			return POLLIN | POLLRDNORM;
 		else {
@@ -1049,13 +1077,11 @@ static int reverse_path_check_proc(void *priv, void *cookie, int call_nests)
  */
 static int reverse_path_check(void)
 {
-	int length = 0;
 	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) {
-		length++;
 		path_count_init();
 		error = ep_call_nested(&poll_loop_ncalls, EP_MAX_NESTS,
 					reverse_path_check_proc, current_file,
@@ -1097,6 +1123,7 @@ static int ep_insert(struct eventpoll *ep, struct epoll_event *event,
 	/* 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.
@@ -1191,6 +1218,9 @@ static int ep_modify(struct eventpoll *ep, struct epitem *epi, struct epoll_even
 {
 	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();
@@ -1198,13 +1228,14 @@ static int ep_modify(struct eventpoll *ep, struct epitem *epi, struct epoll_even
 	 * 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 */
 
 	/*
 	 * Get current event bits. We can safely use the file* here because
 	 * its usage count has been increased by the caller of this function.
 	 */
-	revents = epi->ffd.file->f_op->poll(epi->ffd.file, NULL);
+	revents = epi->ffd.file->f_op->poll(epi->ffd.file, &pt);
 
 	/*
 	 * If the item is "hot" and it is not registered inside the ready
@@ -1239,6 +1270,9 @@ static int ep_send_events_proc(struct eventpoll *ep, struct list_head *head,
 	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.
@@ -1251,7 +1285,8 @@ static int ep_send_events_proc(struct eventpoll *ep, struct list_head *head,
 
 		list_del_init(&epi->rdllink);
 
-		revents = epi->ffd.file->f_op->poll(epi->ffd.file, NULL) &
+		pt._key = epi->event.events;
+		revents = epi->ffd.file->f_op->poll(epi->ffd.file, &pt) &
 			epi->event.events;
 
 		/*