diff options
| author | Andrea Righi <righi.andrea@gmail.com> | 2009-03-31 15:25:18 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-04-01 08:59:29 -0700 |
| commit | 66c1ca019078220dc1bf968f2bb18421100ef147 (patch) | |
| tree | b01d28d74bab9d9e3f0f24841a80a272d6f6520a /drivers/video/fbmem.c | |
| parent | 8636a9240cc93efa6b36f4cfe6253e0574f832c6 (diff) | |
fbmem: fix fb_info->lock and mm->mmap_sem circular locking dependency
Fix a circular locking dependency in the frame buffer console driver
pushing down the mutex fb_info->lock.
Circular locking dependecies occur calling the blocking
fb_notifier_call_chain() with fb_info->lock held. Notifier callbacks can
try to acquire mm->mmap_sem, while fb_mmap() acquires the locks in the
reverse order mm->mmap_sem => fb_info->lock.
Tested-by: Andrey Borzenkov <arvidjaar@mail.ru>
Signed-off-by: Andrea Righi <righi.andrea@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
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/fbmem.c')
| -rw-r--r-- | drivers/video/fbmem.c | 11 |
1 files changed, 1 insertions, 10 deletions
diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c index cfd9dce1ce0b..b64f061dd447 100644 --- a/drivers/video/fbmem.c +++ b/drivers/video/fbmem.c @@ -1086,13 +1086,8 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd, return -EINVAL; con2fb.framebuffer = -1; event.data = &con2fb; - - if (!lock_fb_info(info)) - return -ENODEV; event.info = info; fb_notifier_call_chain(FB_EVENT_GET_CONSOLE_MAP, &event); - unlock_fb_info(info); - ret = copy_to_user(argp, &con2fb, sizeof(con2fb)) ? -EFAULT : 0; break; case FBIOPUT_CON2FBMAP: @@ -1109,12 +1104,8 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd, break; } event.data = &con2fb; - if (!lock_fb_info(info)) - return -ENODEV; event.info = info; - ret = fb_notifier_call_chain(FB_EVENT_SET_CONSOLE_MAP, - &event); - unlock_fb_info(info); + ret = fb_notifier_call_chain(FB_EVENT_SET_CONSOLE_MAP, &event); break; case FBIOBLANK: if (!lock_fb_info(info)) |