linux-kernel - [PATCH 5.15 448/917] io-wq: Remove duplicate code in io_workqueue

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Date:   Mon, 15 Nov 2021 17:59:03 +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, Bixuan Cui <cuibixuan@...wei.com>,
        Jens Axboe <axboe@...nel.dk>, Sasha Levin <sashal@...nel.org>,
        Hao Xu <haoxu@...ux.alibaba.com>
Subject: [PATCH 5.15 448/917] io-wq: Remove duplicate code in io_workqueue_create()

From: Bixuan Cui <cuibixuan@...wei.com>

[ Upstream commit 71e1cef2d794338cc7b979d4c6144e1dc12718b5 ]

While task_work_add() in io_workqueue_create() is true,
then duplicate code is executed:

  -> clear_bit_unlock(0, &worker->create_state);
  -> io_worker_release(worker);
  -> atomic_dec(&acct->nr_running);
  -> io_worker_ref_put(wq);
  -> return false;

  -> clear_bit_unlock(0, &worker->create_state); // back to io_workqueue_create()
  -> io_worker_release(worker);
  -> kfree(worker);

The io_worker_release() and clear_bit_unlock() are executed twice.

Fixes: 3146cba99aa2 ("io-wq: make worker creation resilient against signals")
Signed-off-by: Bixuan Cui <cuibixuan@...wei.com>
Link: https://lore.kernel.org/r/20210911085847.34849-1-cuibixuan@huawei.com
Reviwed-by: Hao Xu <haoxu@...ux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/io-wq.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/fs/io-wq.c b/fs/io-wq.c
index 203c0e2a5dfae..5d189b24a8d4b 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -359,8 +359,10 @@ static bool io_queue_worker_create(struct io_worker *worker,
 
 	init_task_work(&worker->create_work, func);
 	worker->create_index = acct->index;
-	if (!task_work_add(wq->task, &worker->create_work, TWA_SIGNAL))
+	if (!task_work_add(wq->task, &worker->create_work, TWA_SIGNAL)) {
+		clear_bit_unlock(0, &worker->create_state);
 		return true;
+	}
 	clear_bit_unlock(0, &worker->create_state);
 fail_release:
 	io_worker_release(worker);
@@ -765,11 +767,8 @@ static void io_workqueue_create(struct work_struct *work)
 	struct io_worker *worker = container_of(work, struct io_worker, work);
 	struct io_wqe_acct *acct = io_wqe_get_acct(worker);
 
-	if (!io_queue_worker_create(worker, acct, create_worker_cont)) {
-		clear_bit_unlock(0, &worker->create_state);
-		io_worker_release(worker);
+	if (!io_queue_worker_create(worker, acct, create_worker_cont))
 		kfree(worker);
-	}
 }
 
 static bool create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index)
-- 
2.33.0