[ARM] pxafb: avoid the racing condition in pxafb_smart_thread

fbi->state change shall really be protected by fbi->ctrlr_lock, where
the change is sheltered. There is a possibility that pxafb_smart_thread
will start update the LCD panel when fbi->state == C_ENABLE, while
all other initialization isn't done.

Signed-off-by: Eric Miao <eric.miao@marvell.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/video/pxafb.c b/drivers/video/pxafb.c
index 1e1c4ec0d3b9..ab689597f259 100644
--- a/drivers/video/pxafb.c
+++ b/drivers/video/pxafb.c
@@ -794,11 +794,15 @@ static int pxafb_smart_thread(void *arg)
                 if (try_to_freeze())
                         continue;
 
+                mutex_lock(&fbi->ctrlr_lock);
+
                 if (fbi->state == C_ENABLE) {
                         inf->smart_update(&fbi->fb);
                         complete(&fbi->refresh_done);
                 }
 
+                mutex_unlock(&fbi->ctrlr_lock);
+
                 set_current_state(TASK_INTERRUPTIBLE);
                 schedule_timeout(30 * HZ / 1000);
         }