diff options
| author | Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com> | 2021-07-24 19:18:22 +0800 |
|---|---|---|
| committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2021-07-28 23:19:58 +0200 |
| commit | 28be2405fb753927e18bc1a891617a430b2a0684 (patch) | |
| tree | f89e80dbe10270475f16bc34b56742ede4e148a9 /drivers/gpu/drm/drm_auth.c | |
| parent | c29758cdc78ab4ff2431e02015dd26aefa5097c9 (diff) | |
drm: use the lookup lock in drm_is_current_master
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
Diffstat (limited to 'drivers/gpu/drm/drm_auth.c')
| -rw-r--r-- | drivers/gpu/drm/drm_auth.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c index 3a64a6a79ade..5b1d92f5afea 100644 --- a/drivers/gpu/drm/drm_auth.c +++ b/drivers/gpu/drm/drm_auth.c @@ -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; } |