From: Daniel Vetter Date: Thu, 9 Jul 2015 21:32:34 +0000 (+0200) Subject: drm/cma-helper: Fix locking in drm_fb_cma_debugfs_show X-Git-Tag: firefly_0821_release~176^2~1083^2~38^2~3 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=9e75c0ef1428ae8a6bfb340ba2402471752c4af5;p=firefly-linux-kernel-4.4.55.git drm/cma-helper: Fix locking in drm_fb_cma_debugfs_show This function takes two locks, both of them the wrong ones. This wasn't an oversight from my fb locking rework since both patches landed in parallel. We really only need fb_lock when walking that list, since everything we can reach from that is refcounted properly already. v2: Drop unused dev spotted by 0day. Cc: Rob Clark Cc: Laurent Pinchart Signed-off-by: Daniel Vetter --- diff --git a/drivers/gpu/drm/drm_fb_cma_helper.c b/drivers/gpu/drm/drm_fb_cma_helper.c index 5c1aca443e54..46c4e6ee1cb1 100644 --- a/drivers/gpu/drm/drm_fb_cma_helper.c +++ b/drivers/gpu/drm/drm_fb_cma_helper.c @@ -209,23 +209,11 @@ int drm_fb_cma_debugfs_show(struct seq_file *m, void *arg) struct drm_info_node *node = (struct drm_info_node *) m->private; struct drm_device *dev = node->minor->dev; struct drm_framebuffer *fb; - int ret; - - ret = mutex_lock_interruptible(&dev->mode_config.mutex); - if (ret) - return ret; - - ret = mutex_lock_interruptible(&dev->struct_mutex); - if (ret) { - mutex_unlock(&dev->mode_config.mutex); - return ret; - } + mutex_lock(&dev->mode_config.fb_lock); list_for_each_entry(fb, &dev->mode_config.fb_list, head) drm_fb_cma_describe(fb, m); - - mutex_unlock(&dev->struct_mutex); - mutex_unlock(&dev->mode_config.mutex); + mutex_unlock(&dev->mode_config.fb_lock); return 0; } diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c index bd75f303da63..9edad11dca98 100644 --- a/drivers/gpu/drm/drm_gem_cma_helper.c +++ b/drivers/gpu/drm/drm_gem_cma_helper.c @@ -381,11 +381,8 @@ void drm_gem_cma_describe(struct drm_gem_cma_object *cma_obj, struct seq_file *m) { struct drm_gem_object *obj = &cma_obj->base; - struct drm_device *dev = obj->dev; uint64_t off; - WARN_ON(!mutex_is_locked(&dev->struct_mutex)); - off = drm_vma_node_start(&obj->vma_node); seq_printf(m, "%2d (%2d) %08llx %pad %p %zu",