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fbdev: add mutex for fb_mmap locking

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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>
This commit is contained in:
Krzysztof Helt 2009-06-30 11:41:29 -07:00 • committed by Linus Torvalds
parent 70d6027ff2
commit 537a1bf059
16 changed files with 74 additions and 42 deletions
Download patch file Download diff file Expand all files Collapse all files

4
drivers/video/omap/omapfb_main.c
View file

@ -393,8 +393,10 @@ static void set_fb_fix(struct fb_info *fbi)
rg = &plane->fbdev->mem_desc.region[plane->idx];
fbi->screen_base = rg->vaddr;
mutex_lock(&fbi->mm_lock);
fix->smem_start = rg->paddr;
fix->smem_len = rg->size;
mutex_unlock(&fbi->mm_lock);
fix->type = FB_TYPE_PACKED_PIXELS;
bpp = var->bits_per_pixel;
@ -886,8 +888,10 @@ static int omapfb_setup_mem(struct fb_info *fbi, struct omapfb_mem_info *mi)
* plane memory is dealloce'd, the other
* screen parameters in var / fix are invalid.
*/
mutex_lock(&fbi->mm_lock);
fbi->fix.smem_start = 0;
fbi->fix.smem_len = 0;
mutex_unlock(&fbi->mm_lock);
}
}
}