path: root/include/linux/fb.h
diff options
authorAndrea Righi <righi.andrea@gmail.com>2009-02-04 15:12:03 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-02-05 12:56:46 -0800
commit1f5e31d7e55ac7fbd4ec5e5b20c8868b0e4564c9 (patch)
tree713d0ace63c95da9b989aafce8ec84ebb1d1cbc3 /include/linux/fb.h
parentafd8d0f940ba5078f38e435440089117ac7d9eb4 (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/linux/fb.h')
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)