On Sun, Jul 05, 2009 at 07:19:33AM -0700, Linus Torvalds wrote: > > > On Sun, 5 Jul 2009, Wu Zhangjin wrote: > > > > then it works! so, I guess there is a deadlock introduced by the above > > commit. > > Hmm. Perhaps more likely, the 'mm_lock' mutex hasn't even been initialized > yet. We appear to have had that problem with matroxfb and sm501fb, and it > may be more common than that. See commit f50bf2b2. > > That said, I do agree that the mm_lock seems to be causing more problems > than it actually fixes, and maybe we should revert it. Krzysztof? > Looking at this a bit closer, just moving the mutex initialization in to framebuffer_alloc() should basically fix most of these, at least it certainly does for sm501fb and for this sis case as well. So, here's a patch to do that. As an aside note, matroxfb is the odd one out, as it doesn't use framebuffer_alloc() directly for whatever reason. This actually raises an additional issue, in that framebuffer_alloc() is already where other mutexes are initialized, which will simply never happen on matroxfb (suggesting that at least the FB_BACKLIGHT and matroxfb combination will blow up, although perhaps that's not a valid combination). Signed-off-by: Paul Mundt <lethal@xxxxxxxxxxxx> --- drivers/video/fbmem.c | 1 - drivers/video/fbsysfs.c | 2 ++ 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c index 53ea056..27a5271 100644 --- a/drivers/video/fbmem.c +++ b/drivers/video/fbmem.c @@ -1514,7 +1514,6 @@ register_framebuffer(struct fb_info *fb_info) break; fb_info->node = i; mutex_init(&fb_info->lock); - mutex_init(&fb_info->mm_lock); fb_info->dev = device_create(fb_class, fb_info->device, MKDEV(FB_MAJOR, i), NULL, "fb%d", i); diff --git a/drivers/video/fbsysfs.c b/drivers/video/fbsysfs.c index d4a2c11..dd413ad 100644 --- a/drivers/video/fbsysfs.c +++ b/drivers/video/fbsysfs.c @@ -62,6 +62,8 @@ struct fb_info *framebuffer_alloc(size_t size, struct device *dev) mutex_init(&info->bl_curve_mutex); #endif + mutex_init(&info->mm_lock); + return info; #undef PADDING #undef BYTES_PER_LONG
