tree 1d82d028365803386916ca80be95ca36ab549c44
parent f0906e2b7cb9996209ecccf3efe7d47f16c86348
author Eric Biggers <ebiggers@google.com> 1639182512 -0800
committer Karsten Tausche <karsten@fairphone.com> 1648458789 +0200

signalfd: use wake_up_pollfree()

commit 9537bae0da1f8d1e2361ab6d0479e8af7824e160 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Change-Id: I2534cce4e3d5be1b439b01eb8717903e08bb8e65
Issue: FP3SEC-255
(cherry picked from commit 5ecb4e93d70a21f3b7094029986ef0c3e321f56c)