jbd: Fix lock ordering bug in journal_unmap_buffer()

[firefly-linux-kernel-4.4.55.git] / fs / signalfd.c

diff --git a/fs/signalfd.c b/fs/signalfd.c
index 492465b451ddd34f6f60214fb48224687649faa9..7ae2a574cb25a64902128f53832b317202dbee8f 100644 (file)
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -30,6 +30,21 @@
 #include <linux/signalfd.h>
 #include <linux/syscalls.h>
 
+void signalfd_cleanup(struct sighand_struct *sighand)
+{
+       wait_queue_head_t *wqh = &sighand->signalfd_wqh;
+       /*
+        * The lockless check can race with remove_wait_queue() in progress,
+        * but in this case its caller should run under rcu_read_lock() and
+        * sighand_cachep is SLAB_DESTROY_BY_RCU, we can safely return.
+        */
+       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;
 };