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authorEric Biggers <ebiggers@google.com>2021-12-09 04:04:53 +0300
committerEric Biggers <ebiggers@google.com>2021-12-09 21:49:56 +0300
commit9537bae0da1f8d1e2361ab6d0479e8af7824e160 (patch)
tree5afede8161feeef64b89b0eb31fcd12aaa7a2955 /fs/signalfd.c
parenta880b28a71e39013e357fd3adccd1d8a31bc69a8 (diff)
downloadlinux-9537bae0da1f8d1e2361ab6d0479e8af7824e160.tar.xz
signalfd: use wake_up_pollfree()
wake_up_poll() uses nr_exclusive=1, so it's not guaranteed to wake up all exclusive waiters. Yet, POLLFREE *must* wake up all waiters. epoll and aio poll are fortunately not affected by this, but it's very fragile. Thus, the new function wake_up_pollfree() has been introduced. Convert signalfd to use wake_up_pollfree(). Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Fixes: d80e731ecab4 ("epoll: introduce POLLFREE to flush ->signalfd_wqh before kfree()") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20211209010455.42744-4-ebiggers@kernel.org Signed-off-by: Eric Biggers <ebiggers@google.com>
Diffstat (limited to 'fs/signalfd.c')
-rw-r--r--fs/signalfd.c12
1 files changed, 1 insertions, 11 deletions
diff --git a/fs/signalfd.c b/fs/signalfd.c
index 040e1cf90528..65ce0e72e7b9 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -35,17 +35,7 @@
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_TYPESAFE_BY_RCU, we can safely return.
- */
- if (likely(!waitqueue_active(wqh)))
- return;
-
- /* wait_queue_entry_t->func(POLLFREE) should do remove_wait_queue() */
- wake_up_poll(wqh, EPOLLHUP | POLLFREE);
+ wake_up_pollfree(&sighand->signalfd_wqh);
}
struct signalfd_ctx {