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authorKrzysztof Helt <krzysztof.h1@wp.pl>2009-06-30 11:41:29 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-06-30 18:56:00 -0700
commit537a1bf059fa312355696fa6db80726e655e7f17 (patch)
tree4f5b3c6917311cfefad21eaf3dd92978334282de /drivers/video/atmel_lcdfb.c
parent70d6027ff2bc8bab180273b77e7ab3e8a62cca51 (diff)
fbdev: add mutex for fb_mmap locking
Add a mutex to avoid a circular locking problem between the mm layer semaphore and fbdev ioctl mutex through the fb_mmap() call. Also, add mutex to all places where smem_start and smem_len fields change so the mutex inside the fb_mmap() is actually used. Changing of these fields before calling the framebuffer_register() are not mutexed. This is 2.6.31 material. It removes one lockdep (fb_mmap() and register_framebuffer()) but there is still another one (fb_release() and register_framebuffer()). It also cleans up handling of the smem_start and smem_len fields used by mutexed section of the fb_mmap(). Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/video/atmel_lcdfb.c')
-rw-r--r--drivers/video/atmel_lcdfb.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/video/atmel_lcdfb.c b/drivers/video/atmel_lcdfb.c
index 5afd64482f5..cb88394ba99 100644
--- a/drivers/video/atmel_lcdfb.c
+++ b/drivers/video/atmel_lcdfb.c
@@ -270,7 +270,9 @@ static int atmel_lcdfb_alloc_video_memory(struct atmel_lcdfb_info *sinfo)
smem_len = (var->xres_virtual * var->yres_virtual
* ((var->bits_per_pixel + 7) / 8));
+ mutex_lock(&info->mm_lock);
info->fix.smem_len = max(smem_len, sinfo->smem_len);
+ mutex_unlock(&info->mm_lock);
info->screen_base = dma_alloc_writecombine(info->device, info->fix.smem_len,
(dma_addr_t *)&info->fix.smem_start, GFP_KERNEL);