media: imon: Fix race getting ictx->lock

Lets fix a race between mutex_is_lock() and mutex_lock().

<-mutex is not locked
if (!mutex_is_locked(&ictx->lock)) {
	unlock = true; <- mutex is locked externaly
	mutex_lock(&ictx->lock);
}

Let's use mutex_trylock() that does mutex_is_lock() and mutex_lock()
atomically.

Fix the following cocci warning:
drivers/media/rc/imon.c:1167:1-7: preceding lock on line 1153

Fixes: 23ef710e1a6c ("[media] imon: add conditional locking in change_protocol")
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

diff --git a/drivers/media/rc/imon.c b/drivers/media/rc/imon.c
index 0b55314a80827b1aa4d6ea897d4b5220b6fd48ba..8f1361bcce3a608bca8d598b64ac683c0b5fc18b 100644 (file)
--- a/drivers/media/rc/imon.c
+++ b/drivers/media/rc/imon.c
@@ -1148,10 +1148,7 @@ static int imon_ir_change_protocol(struct rc_dev *rc, u64 *rc_proto)
 
        memcpy(ictx->usb_tx_buf, &ir_proto_packet, sizeof(ir_proto_packet));
 
-       if (!mutex_is_locked(&ictx->lock)) {
-               unlock = true;
-               mutex_lock(&ictx->lock);
-       }
+       unlock = mutex_trylock(&ictx->lock);
 
        retval = send_packet(ictx);
        if (retval)