mei: fix mismatch in mutex unlock-lock in mei_amthif_read()

Users of mei_amthif_read() expect it leaves dev->device_lock held,
while there is a path where mei_amthif_read() unlocks device_lock
and returns -ERESTARTSYS.

The patch move code locking device_lock back before the return.

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

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Cc: Sedat Dilek <sedat.dilek@gmail.com>
Acked-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 3 insertions, 3 deletions

diff --git a/drivers/misc/mei/amthif.c b/drivers/misc/mei/amthif.c
index 18794aea6062..e40ffd9502d1 100644
--- a/drivers/misc/mei/amthif.c
+++ b/drivers/misc/mei/amthif.c
@@ -187,13 +187,13 @@ int mei_amthif_read(struct mei_device *dev, struct file *file,
                 wait_ret = wait_event_interruptible(dev->iamthif_cl.wait,
                         (cb = mei_amthif_find_read_list_entry(dev, file)));
 
+                /* Locking again the Mutex */
+                mutex_lock(&dev->device_lock);
+
                 if (wait_ret)
                         return -ERESTARTSYS;
 
                 dev_dbg(&dev->pdev->dev, "woke up from sleep\n");
-
-                /* Locking again the Mutex */
-                mutex_lock(&dev->device_lock);
         }