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[129.78.56.229]) by smtp.gmail.com with ESMTPSA id x18sm988009pfp.57.2021.04.28.20.45.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 28 Apr 2021 20:45:31 -0700 (PDT) From: Baptiste Lepers Cc: trivial@kernel.org, Baptiste Lepers , Alexander Viro , Andrew Morton , Miklos Szeredi , Tejun Heo , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] poll: Ignore benign race on pwd->triggered Date: Thu, 29 Apr 2021 13:44:11 +1000 Message-Id: <20210429034411.6379-1-baptiste.lepers@gmail.com> X-Mailer: git-send-email 2.17.1 To: unlisted-recipients:; (no To-header on input) Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Mark data races to pwd->triggered as benign using READ_ONCE and WRITE_ONCE. These accesses are expected to be racy per comment. This patch is part of a series of patches aiming at reducing the number of benign races reported by KCSAN in order to focus future debugging effort on harmful races. Reported-by: syzbot+9b3fb64bcc8c1d807595@syzkaller.appspotmail.com Fixes: 5f820f648c92a ("poll: allow f_op->poll to sleep") Signed-off-by: Baptiste Lepers Acked-by: Marco Elver --- fs/select.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/select.c b/fs/select.c index 945896d0ac9e..e71b4d1a2606 100644 --- a/fs/select.c +++ b/fs/select.c @@ -194,7 +194,7 @@ static int __pollwake(wait_queue_entry_t *wait, unsigned mode, int sync, void *k * and is paired with smp_store_mb() in poll_schedule_timeout. */ smp_wmb(); - pwq->triggered = 1; + WRITE_ONCE(pwq->triggered, 1); /* * Perform the default wake up operation using a dummy @@ -239,7 +239,7 @@ static int poll_schedule_timeout(struct poll_wqueues *pwq, int state, int rc = -EINTR; set_current_state(state); - if (!pwq->triggered) + if (!READ_ONCE(pwq->triggered)) rc = schedule_hrtimeout_range(expires, slack, HRTIMER_MODE_ABS); __set_current_state(TASK_RUNNING);