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| author | Eric Biggers <ebiggers@google.com> | 2021-12-10 16:19:26 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-12-14 10:16:55 +0100 |
| commit | c1574af60c4aef85fc05c17458653fc04cd20ff7 (patch) | |
| tree | b2b6b75a15fa3fd099efe05874663e17c8cdf3b5 | |
| parent | 7bfd8e1fd8d2a4c5df1ae67d2ee3481b8f53904c (diff) | |
| download | linux-stable-c1574af60c4aef85fc05c17458653fc04cd20ff7.tar.gz linux-stable-c1574af60c4aef85fc05c17458653fc04cd20ff7.tar.bz2 linux-stable-c1574af60c4aef85fc05c17458653fc04cd20ff7.zip | |
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>
| -rw-r--r-- | fs/signalfd.c | 12 |
1 files changed, 1 insertions, 11 deletions
diff --git a/fs/signalfd.c b/fs/signalfd.c index 1c667af86da5..0b7c6c2c95b8 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, POLLHUP | POLLFREE); + wake_up_pollfree(&sighand->signalfd_wqh); } struct signalfd_ctx { |