On Fri, Apr 15, 2016 at 03:10:41PM +1000, Dave Airlie wrote: > From: Dave Airlie <airlied@xxxxxxxxxx> > > This reduces the fb_lock to just protecting the num_fb/fb_list. > > I'd like to have some discussion on if this opens up any race > conditions. Here's you're discussion ;-) "Previously fb refcounting, and especially the weak reference (kref_get_unless_zero) used in fb lookups have been protected by fb_lock. But with the refactoring to share refcounting in the drm_mode_object base class that switched to being protected by idr_mutex, which means fb_lock critical sections can be reduced." Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx> > > Signed-off-by: Dave Airlie <airlied@xxxxxxxxxx> > --- > drivers/gpu/drm/drm_crtc.c | 9 +-------- > 1 file changed, 1 insertion(+), 8 deletions(-) > > diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c > index e47c4a2..46f32f2 100644 > --- a/drivers/gpu/drm/drm_crtc.c > +++ b/drivers/gpu/drm/drm_crtc.c > @@ -433,9 +433,7 @@ static void drm_framebuffer_free(struct kref *kref) > * The lookup idr holds a weak reference, which has not necessarily been > * removed at this point. Check for that. > */ > - mutex_lock(&dev->mode_config.fb_lock); > drm_mode_object_unregister(dev, &fb->base); > - mutex_unlock(&dev->mode_config.fb_lock); > > fb->funcs->destroy(fb); > } > @@ -475,9 +473,9 @@ int drm_framebuffer_init(struct drm_device *dev, struct drm_framebuffer *fb, > mutex_lock(&dev->mode_config.fb_lock); > dev->mode_config.num_fb++; > list_add(&fb->head, &dev->mode_config.fb_list); > + mutex_unlock(&dev->mode_config.fb_lock); > > drm_mode_object_register(dev, &fb->base); > - mutex_unlock(&dev->mode_config.fb_lock); > out: > return ret; > } > @@ -498,12 +496,9 @@ struct drm_framebuffer *drm_framebuffer_lookup(struct drm_device *dev, > struct drm_mode_object *obj; > struct drm_framebuffer *fb = NULL; > > - mutex_lock(&dev->mode_config.fb_lock); > obj = _object_find(dev, id, DRM_MODE_OBJECT_FB); > if (obj) > fb = obj_to_fb(obj); > - mutex_unlock(&dev->mode_config.fb_lock); > - > return fb; > } > EXPORT_SYMBOL(drm_framebuffer_lookup); > @@ -526,10 +521,8 @@ void drm_framebuffer_unregister_private(struct drm_framebuffer *fb) > > dev = fb->dev; > > - mutex_lock(&dev->mode_config.fb_lock); > /* Mark fb as reaped and drop idr ref. */ > drm_mode_object_unregister(dev, &fb->base); > - mutex_unlock(&dev->mode_config.fb_lock); > } > EXPORT_SYMBOL(drm_framebuffer_unregister_private); > > -- > 2.5.5 > > _______________________________________________ > dri-devel mailing list > dri-devel@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
