staging/easycap: fix mismatch in easycap_poll() mutex lock-unlock

In case if condition (kd != isdongle(peasycap)) becomes true,
easycap_poll() returns without releasing easycapdc60_dongle[kd].mutex_video.
The patch adds mutex_unlock() before that return.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Acked-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/staging/easycap/easycap_main.c b/drivers/staging/easycap/easycap_main.c
index bea281624c4..3ea51c37391 100644
--- a/drivers/staging/easycap/easycap_main.c
+++ b/drivers/staging/easycap/easycap_main.c
@@ -953,8 +953,10 @@ static unsigned int easycap_poll(struct file *file, poll_table *wait)
          *  peasycap, IN WHICH CASE A REPEAT CALL TO isdongle() WILL FAIL.
          *  IF NECESSARY, BAIL OUT.
          */
-                if (kd != isdongle(peasycap))
+                if (kd != isdongle(peasycap)) {
+                        mutex_unlock(&easycapdc60_dongle[kd].mutex_video);
                         return -ERESTARTSYS;
+                }
                 if (!file) {
                         SAY("ERROR:  file is NULL\n");
                         mutex_unlock(&easycapdc60_dongle[kd].mutex_video);