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drm/mode: reduce scope of fb_lock in framebuffer init

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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 <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Dave Airlie 2016-04-15 15:10:38 +10:00
parent cee26ac47d
commit 9cd47424fb
1 changed files with 5 additions and 4 deletions
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9
drivers/gpu/drm/drm_crtc.c
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@ -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);