Messages in this thread Patch in this message | | | From | Chengfeng Ye <> | Subject | [PATCH v2 2/2] gpiolib: cdev: Fix &le->wait.lock deadlock issue | Date | Mon, 26 Jun 2023 14:57:56 +0000 |
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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 <dg573847474@gmail.com> --- 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 -- 2.17.1
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