linux-kernel - [PATCH 5.15 166/177] io-wq: remove spurious bit clear on task

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Message-Id: <20211220143045.663691870@linuxfoundation.org>
Date:   Mon, 20 Dec 2021 15:35:16 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        syzbot+b60c982cb0efc5e05a47@...kaller.appspotmail.com,
        Jens Axboe <axboe@...nel.dk>
Subject: [PATCH 5.15 166/177] io-wq: remove spurious bit clear on task_work addition

From: Jens Axboe <axboe@...nel.dk>

commit e47498afeca9a0c6d07eeeacc46d563555a3f677 upstream.

There's a small race here where the task_work could finish and drop
the worker itself, so that by the time that task_work_add() returns
with a successful addition we've already put the worker.

The worker callbacks clear this bit themselves, so we don't actually
need to manually clear it in the caller. Get rid of it.

Reported-by: syzbot+b60c982cb0efc5e05a47@...kaller.appspotmail.com
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/io-wq.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -359,10 +359,8 @@ static bool io_queue_worker_create(struc
 
 	init_task_work(&worker->create_work, func);
 	worker->create_index = acct->index;
-	if (!task_work_add(wq->task, &worker->create_work, TWA_SIGNAL)) {
-		clear_bit_unlock(0, &worker->create_state);
+	if (!task_work_add(wq->task, &worker->create_work, TWA_SIGNAL))
 		return true;
-	}
 	clear_bit_unlock(0, &worker->create_state);
 fail_release:
 	io_worker_release(worker);