drm/mode: reduce scope of fb_lock in framebuffer init

We don't need to hold the fb lock around the initialisation,
only around the list manipulaton.

So do the lock hold only around the register for now.

From Daniel:
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 <[email protected]>
Signed-off-by: Dave Airlie <[email protected]>

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 0e4e25509c3d5c5bb9f821ba66d6c58c642b69de..b088840582cc376796bd745f5b9003cc8bb02ef0 100644 (file)
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -458,21 +458,22 @@ int drm_framebuffer_init(struct drm_device *dev, struct drm_framebuffer *fb,
 {
        int ret;
 
-       mutex_lock(&dev->mode_config.fb_lock);
        INIT_LIST_HEAD(&fb->filp_head);
        fb->dev = dev;
        fb->funcs = funcs;
 
        ret = drm_mode_object_get_reg(dev, &fb->base, DRM_MODE_OBJECT_FB,
-                                     true, drm_framebuffer_free);
+                                     false, drm_framebuffer_free);
        if (ret)
                goto out;
 
+       mutex_lock(&dev->mode_config.fb_lock);
        dev->mode_config.num_fb++;
        list_add(&fb->head, &dev->mode_config.fb_list);
-out:
-       mutex_unlock(&dev->mode_config.fb_lock);
 
+       drm_mode_object_register(dev, &fb->base);
+       mutex_unlock(&dev->mode_config.fb_lock);
+out:
        return ret;
 }
 EXPORT_SYMBOL(drm_framebuffer_init);