path: root/drivers/video/mx3fb.c
diff options
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/mx3fb.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/mx3fb.c')
1 files changed, 11 insertions, 6 deletions
diff --git a/drivers/video/mx3fb.c b/drivers/video/mx3fb.c
index b7af5256e88..567fb944bd2 100644
--- a/drivers/video/mx3fb.c
+++ b/drivers/video/mx3fb.c
@@ -669,7 +669,7 @@ static uint32_t bpp_to_pixfmt(int bpp)
static int mx3fb_blank(int blank, struct fb_info *fbi);
-static int mx3fb_map_video_memory(struct fb_info *fbi);
+static int mx3fb_map_video_memory(struct fb_info *fbi, unsigned int mem_len);
static int mx3fb_unmap_video_memory(struct fb_info *fbi);
@@ -742,8 +742,7 @@ static int mx3fb_set_par(struct fb_info *fbi)
if (fbi->fix.smem_start)
- fbi->fix.smem_len = mem_len;
- if (mx3fb_map_video_memory(fbi) < 0) {
+ if (mx3fb_map_video_memory(fbi, mem_len) < 0) {
return -ENOMEM;
@@ -1198,6 +1197,7 @@ static int mx3fb_resume(struct platform_device *pdev)
* mx3fb_map_video_memory() - allocates the DRAM memory for the frame buffer.
* @fbi: framebuffer information pointer
+ * @mem_len: length of mapped memory
* @return: Error code indicating success or failure
* This buffer is remapped into a non-cached, non-buffered, memory region to
@@ -1205,23 +1205,26 @@ static int mx3fb_resume(struct platform_device *pdev)
* area is remapped, all virtual memory access to the video memory should occur
* at the new region.
-static int mx3fb_map_video_memory(struct fb_info *fbi)
+static int mx3fb_map_video_memory(struct fb_info *fbi, unsigned int mem_len)
int retval = 0;
dma_addr_t addr;
fbi->screen_base = dma_alloc_writecombine(fbi->device,
- fbi->fix.smem_len,
+ mem_len,
&addr, GFP_DMA);
if (!fbi->screen_base) {
dev_err(fbi->device, "Cannot allocate %u bytes framebuffer memory\n",
- fbi->fix.smem_len);
+ mem_len);
retval = -EBUSY;
goto err0;
+ mutex_lock(&fbi->mm_lock);
fbi->fix.smem_start = addr;
+ fbi->fix.smem_len = mem_len;
+ mutex_unlock(&fbi->mm_lock);
dev_dbg(fbi->device, "allocated fb @ p=0x%08x, v=0x%p, size=%d.\n",
(uint32_t) fbi->fix.smem_start, fbi->screen_base, fbi->fix.smem_len);
@@ -1251,8 +1254,10 @@ static int mx3fb_unmap_video_memory(struct fb_info *fbi)
fbi->screen_base, fbi->fix.smem_start);
fbi->screen_base = 0;
+ mutex_lock(&fbi->mm_lock);
fbi->fix.smem_start = 0;
fbi->fix.smem_len = 0;
+ mutex_unlock(&fbi->mm_lock);
return 0;