5 files changed, 25 insertions, 2 deletions

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index aabdfc38cf24..34bbfc6dd8dc 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -842,6 +842,10 @@ static int ep_poll_callback(wait_queue_t *wait, unsigned mode, int sync, void *k
         struct epitem *epi = ep_item_from_wait(wait);
         struct eventpoll *ep = epi->ep;
 
+        /* the caller holds eppoll_entry->whead->lock */
+        if ((unsigned long)key & POLLFREE)
+                list_del_init(&wait->task_list);
+
         spin_lock_irqsave(&ep->lock, flags);
 
         /*
diff --git a/fs/signalfd.c b/fs/signalfd.c
index 492465b451dd..79c1eea98a3a 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -30,6 +30,17 @@
 #include <linux/signalfd.h>
 #include <linux/syscalls.h>
 
+void signalfd_cleanup(struct sighand_struct *sighand)
+{
+        wait_queue_head_t *wqh = &sighand->signalfd_wqh;
+
+        if (likely(!waitqueue_active(wqh)))
+                return;
+
+        /* wait_queue_t->func(POLLFREE) should do remove_wait_queue() */
+        wake_up_poll(wqh, POLLHUP | POLLFREE);
+}
+
 struct signalfd_ctx {
         sigset_t sigmask;
 };
diff --git a/include/asm-generic/poll.h b/include/asm-generic/poll.h
index 44bce836d350..9ce7f44aebd2 100644
--- a/include/asm-generic/poll.h
+++ b/include/asm-generic/poll.h
@@ -28,6 +28,8 @@
 #define POLLRDHUP       0x2000
 #endif
 
+#define POLLFREE        0x4000  /* currently only for epoll */
+
 struct pollfd {
         int fd;
         short events;
diff --git a/include/linux/signalfd.h b/include/linux/signalfd.h
index 3ff4961da9b5..247399b2979a 100644
--- a/include/linux/signalfd.h
+++ b/include/linux/signalfd.h
@@ -61,13 +61,16 @@ static inline void signalfd_notify(struct task_struct *tsk, int sig)
                 wake_up(&tsk->sighand->signalfd_wqh);
 }
 
+extern void signalfd_cleanup(struct sighand_struct *sighand);
+
 #else /* CONFIG_SIGNALFD */
 
 static inline void signalfd_notify(struct task_struct *tsk, int sig) { }
 
+static inline void signalfd_cleanup(struct sighand_struct *sighand) { }
+
 #endif /* CONFIG_SIGNALFD */
 
 #endif /* __KERNEL__ */
 
 #endif /* _LINUX_SIGNALFD_H */
-
diff --git a/kernel/fork.c b/kernel/fork.c
index b77fd559c78e..e2cd3e2a5ae8 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -66,6 +66,7 @@
 #include <linux/user-return-notifier.h>
 #include <linux/oom.h>
 #include <linux/khugepaged.h>
+#include <linux/signalfd.h>
 
 #include <asm/pgtable.h>
 #include <asm/pgalloc.h>
@@ -935,8 +936,10 @@ static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
 
 void __cleanup_sighand(struct sighand_struct *sighand)
 {
-        if (atomic_dec_and_test(&sighand->count))
+        if (atomic_dec_and_test(&sighand->count)) {
+                signalfd_cleanup(sighand);
                 kmem_cache_free(sighand_cachep, sighand);
+        }
 }