diff options
| author | Andrea Righi | 2009-02-04 15:12:03 -0800 |
|---|---|---|
| committer | Linus Torvalds | 2009-02-05 12:56:46 -0800 |
| commit | 1f5e31d7e55ac7fbd4ec5e5b20c8868b0e4564c9 (patch) | |
| tree | 713d0ace63c95da9b989aafce8ec84ebb1d1cbc3 /include | |
| parent | afd8d0f940ba5078f38e435440089117ac7d9eb4 (diff) | |
fbmem: don't call copy_from/to_user() with mutex held
Avoid calling copy_from/to_user() with fb_info->lock mutex held in fbmem
ioctl().
fb_mmap() is called under mm->mmap_sem (A) held, that also acquires
fb_info->lock (B); fb_ioctl() takes fb_info->lock (B) and does
copy_from/to_user() that might acquire mm->mmap_sem (A), causing a
deadlock.
NOTE: it doesn't push down the fb_info->lock in each own driver's
fb_ioctl(), so there are still potential deadlocks elsewhere.
Signed-off-by: Andrea Righi <righi.andrea@gmail.com>
Cc: Dave Jones <davej@redhat.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Johannes Weiner <hannes@saeurebad.de>
Cc: Krzysztof Helt <krzysztof.h1@wp.pl>
Cc: Harvey Harrison <harvey.harrison@gmail.com>
Cc: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/fb.h | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/include/linux/fb.h b/include/linux/fb.h index 818fe21257e8..31527e17076b 100644 --- a/include/linux/fb.h +++ b/include/linux/fb.h @@ -960,6 +960,21 @@ extern struct fb_info *registered_fb[FB_MAX]; extern int num_registered_fb; extern struct class *fb_class; +static inline int lock_fb_info(struct fb_info *info) +{ + mutex_lock(&info->lock); + if (!info->fbops) { + mutex_unlock(&info->lock); + return 0; + } + return 1; +} + +static inline void unlock_fb_info(struct fb_info *info) +{ + mutex_unlock(&info->lock); +} + static inline void __fb_pad_aligned_buffer(u8 *dst, u32 d_pitch, u8 *src, u32 s_pitch, u32 height) { |