linux-kernel - [PATCH RT 2/3] aio: Fix incorrect usage of eventfd_signal

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Date:   Wed,  9 Mar 2022 09:27:47 -0600
From:   zanussi@...nel.org
To:     LKML <linux-kernel@...r.kernel.org>,
        linux-rt-users <linux-rt-users@...r.kernel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Carsten Emde <C.Emde@...dl.org>,
        John Kacur <jkacur@...hat.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Daniel Wagner <wagi@...om.org>,
        Clark Williams <williams@...hat.com>,
        "Luis Claudio R. Goncalves" <lgoncalv@...hat.com>,
        Tom Zanussi <zanussi@...nel.org>
Cc:     Xie Yongji <xieyongji@...edance.com>,
        Eric Biggers <ebiggers@...gle.com>
Subject: [PATCH RT 2/3] aio: Fix incorrect usage of eventfd_signal_allowed()

From: Xie Yongji <xieyongji@...edance.com>

v5.4.182-rt71-rc1 stable review patch.
If anyone has any objections, please let me know.

-----------


[ Upstream commmit 4b3749865374899e115aa8c48681709b086fe6d3 ]

We should defer eventfd_signal() to the workqueue when
eventfd_signal_allowed() return false rather than return
true.

Fixes: b542e383d8c0 ("eventfd: Make signal recursion protection a task bit")
Signed-off-by: Xie Yongji <xieyongji@...edance.com>
Link: https://lore.kernel.org/r/20210913111928.98-1-xieyongji@bytedance.com
Reviewed-by: Eric Biggers <ebiggers@...gle.com>
Signed-off-by: Eric Biggers <ebiggers@...gle.com>
Signed-off-by: Tom Zanussi <zanussi@...nel.org>
---
 fs/aio.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/aio.c b/fs/aio.c
index db21ca695781..0bb9abf39065 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1767,7 +1767,7 @@ static int aio_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,
 		list_del_init(&req->wait.entry);
 		list_del(&iocb->ki_list);
 		iocb->ki_res.res = mangle_poll(mask);
-		if (iocb->ki_eventfd && eventfd_signal_allowed()) {
+		if (iocb->ki_eventfd && !eventfd_signal_allowed()) {
 			iocb = NULL;
 			INIT_WORK(&req->work, aio_poll_put_work);
 			schedule_work(&req->work);
-- 
2.17.1