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[143.89.191.97]) by smtp.gmail.com with ESMTPSA id x20-20020a170902821400b001b1a2bf5277sm4313303pln.39.2023.06.26.07.58.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 26 Jun 2023 07:58:07 -0700 (PDT) From: Chengfeng Ye To: linus.walleij@linaro.org, brgl@bgdev.pl, andy@kernel.org Cc: linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, cyeaa@connect.ust.hk, Chengfeng Ye Subject: [PATCH v2 2/2] gpiolib: cdev: Fix &le->wait.lock deadlock issue Date: Mon, 26 Jun 2023 14:57:56 +0000 Message-Id: <20230626145756.30696-2-dg573847474@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20230626145756.30696-1-dg573847474@gmail.com> References: <20230626145756.30696-1-dg573847474@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-gpio@vger.kernel.org The softirq lineevent_irq_thread() could deadlock on &le->wait.lock if it preempts lineevent_read_unlocked() which acquires the same lock but not disable irq. Fix the potential deadlock by spin_lock_irq(). Fixes: dea9c80ee672 ("gpiolib: rework the locking mechanism for lineevent kfifo") Signed-off-by: Chengfeng Ye --- drivers/gpio/gpiolib-cdev.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c index f768d46bdea7..a2c108f172f2 100644 --- a/drivers/gpio/gpiolib-cdev.c +++ b/drivers/gpio/gpiolib-cdev.c @@ -1858,28 +1858,28 @@ static ssize_t lineevent_read_unlocked(struct file *file, char __user *buf, return -EINVAL; do { - spin_lock(&le->wait.lock); + spin_lock_irq(&le->wait.lock); if (kfifo_is_empty(&le->events)) { if (bytes_read) { - spin_unlock(&le->wait.lock); + spin_unlock_irq(&le->wait.lock); return bytes_read; } if (file->f_flags & O_NONBLOCK) { - spin_unlock(&le->wait.lock); + spin_unlock_irq(&le->wait.lock); return -EAGAIN; } - ret = wait_event_interruptible_locked(le->wait, + ret = wait_event_interruptible_locked_irq(le->wait, !kfifo_is_empty(&le->events)); if (ret) { - spin_unlock(&le->wait.lock); + spin_unlock_irq(&le->wait.lock); return ret; } } ret = kfifo_out(&le->events, &ge, 1); - spin_unlock(&le->wait.lock); + spin_unlock_irq(&le->wait.lock); if (ret != 1) { /* * This should never happen - we were holding the lock