From: Eric Biggers ebiggers@google.com
stable inclusion from stable-v5.10.85 commit fc2f636ffc446d8e9530e441897f877922269051 bugzilla: 186032 https://gitee.com/openeuler/kernel/issues/I4QVI4
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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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 Signed-off-by: Chen Jun chenjun102@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- fs/signalfd.c | 12 +----------- 1 file changed, 1 insertion(+), 11 deletions(-)
diff --git a/fs/signalfd.c b/fs/signalfd.c index 456046e15873..b94fb5f81797 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 {