From 72fe90b8e72e3f759164d2b4b5c60617a8a1a93e Mon Sep 17 00:00:00 2001 From: Dave Airlie Date: Fri, 15 Apr 2016 15:10:40 +1000 Subject: [PATCH] drm/modes: move reference taking into object lookup. When we lookup an ref counted object we now take a proper reference using kref_get_unless_zero. Framebuffer lookup no longer needs do this itself. Convert rmfb to using framebuffer lookup and deal with the fact it now gets an extra reference that we have to cleanup. This should mean we can avoid holding fb_lock across rmfb. (if I'm wrong let me know). We also now only hold the fbs_lock around the list manipulation. "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 Signed-off-by: Dave Airlie --- drivers/gpu/drm/drm_crtc.c | 37 ++++++++++++++++++++----------------- 1 file changed, 20 insertions(+), 17 deletions(-) diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c index bbf7ce4ead99..e1de47576143 100644 --- a/drivers/gpu/drm/drm_crtc.c +++ b/drivers/gpu/drm/drm_crtc.c @@ -364,6 +364,11 @@ static struct drm_mode_object *_object_find(struct drm_device *dev, if (obj && obj->type == DRM_MODE_OBJECT_BLOB) obj = NULL; + + if (obj && obj->free_cb) { + if (!kref_get_unless_zero(&obj->refcount)) + obj = NULL; + } mutex_unlock(&dev->mode_config.idr_mutex); return obj; @@ -495,11 +500,8 @@ struct drm_framebuffer *drm_framebuffer_lookup(struct drm_device *dev, mutex_lock(&dev->mode_config.fb_lock); obj = _object_find(dev, id, DRM_MODE_OBJECT_FB); - if (obj) { + if (obj) fb = obj_to_fb(obj); - if (!kref_get_unless_zero(&fb->base.refcount)) - fb = NULL; - } mutex_unlock(&dev->mode_config.fb_lock); return fb; @@ -3474,37 +3476,38 @@ int drm_mode_rmfb(struct drm_device *dev, { struct drm_framebuffer *fb = NULL; struct drm_framebuffer *fbl = NULL; - struct drm_mode_object *obj; uint32_t *id = data; int found = 0; if (!drm_core_check_feature(dev, DRIVER_MODESET)) return -EINVAL; + fb = drm_framebuffer_lookup(dev, *id); + if (!fb) + return -ENOENT; + mutex_lock(&file_priv->fbs_lock); - mutex_lock(&dev->mode_config.fb_lock); - obj = _object_find(dev, *id, DRM_MODE_OBJECT_FB); - if (!obj) - goto fail_lookup; - fb = obj_to_fb(obj); list_for_each_entry(fbl, &file_priv->fbs, filp_head) if (fb == fbl) found = 1; - if (!found) - goto fail_lookup; + if (!found) { + mutex_unlock(&file_priv->fbs_lock); + goto fail_unref; + } list_del_init(&fb->filp_head); - mutex_unlock(&dev->mode_config.fb_lock); mutex_unlock(&file_priv->fbs_lock); + /* we now own the reference that was stored in the fbs list */ drm_framebuffer_unreference(fb); - return 0; + /* drop the reference we picked up in framebuffer lookup */ + drm_framebuffer_unreference(fb); -fail_lookup: - mutex_unlock(&dev->mode_config.fb_lock); - mutex_unlock(&file_priv->fbs_lock); + return 0; +fail_unref: + drm_framebuffer_unreference(fb); return -ENOENT; } -- 2.30.2