video: sm501fb: Early initialization of mm_lock mutex.

Commit 537a1bf059fa312355696fa6db80726e655e7f17 (fbdev: add mutex for
fb_mmap locking) introduces a ->mm_lock mutex for protecting smem
assignments. Unfortunately in the case of sm501fb these happen quite
early in the initialization code, well before the mutex_init() that takes
place in register_framebuffer(), leading to:

   Badness at kernel/mutex.c:207

   Pid : 1, Comm:          swapper
   CPU : 0                 Not tainted  (2.6.31-rc1-00284-g529ba0d-dirty #2273)

   PC is at __mutex_lock_slowpath+0x72/0x1bc
   PR is at __mutex_lock_slowpath+0x66/0x1bc
   ...

matroxfb appears to have the same issue and has solved it with an early
mutex_init(), so we do the same for sm501fb.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Cc: Krzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/video/sm501fb.c b/drivers/video/sm501fb.c
index 98f24f0ec00d..16d4f4c7d52b 100644
--- a/drivers/video/sm501fb.c
+++ b/drivers/video/sm501fb.c
@@ -1624,6 +1624,8 @@ static int __devinit sm501fb_start_one(struct sm501fb_info *info,
         if (!fbi)
                 return 0;
 
+        mutex_init(&info->fb[head]->mm_lock);
+
         ret = sm501fb_init_fb(info->fb[head], head, drvname);
         if (ret) {
                 dev_err(info->dev, "cannot initialise fb %s\n", drvname);