tmakin/ack-tegra
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

drm: use the lookup lock in drm_is_current_master

Browse Source 
Inside drm_is_current_master, using the outer drm_device.master_mutex
to protect reads of drm_file.master makes the function prone to creating
lock hierarchy inversions. Instead, we can use the
drm_file.master_lookup_lock that sits at the bottom of the lock
hierarchy.

Reported-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210724111824.59266-2-desmondcheongzx@gmail.com
This commit is contained in:
Desmond Cheong Zhi Xi
2021-07-24 19:18:22 +08:00
committed by Daniel Vetter
parent c29758cdc7
commit 28be2405fb
1 changed files with 5 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files
drivers/gpu/drm/drm_auth.c
+5 -4
View File
@@ -63,8 +63,9 @@
static bool drm_is_current_master_locked(struct drm_file *fpriv)
{
lockdep_assert_held_once(&fpriv->minor->dev->master_mutex);
/* Either drm_device.master_mutex or drm_file.master_lookup_lock
* should be held here.
*/
return fpriv->is_master && drm_lease_owner(fpriv->master) == fpriv->minor->dev->master;
}
@@ -82,9 +83,9 @@ bool drm_is_current_master(struct drm_file *fpriv)
{
bool ret;
mutex_lock(&fpriv->minor->dev->master_mutex);
spin_lock(&fpriv->master_lookup_lock);
ret = drm_is_current_master_locked(fpriv);
mutex_unlock(&fpriv->minor->dev->master_mutex);
spin_unlock(&fpriv->master_lookup_lock);
return ret;
}