diff options
| author |   Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com> | 2021-08-02 18:59:57 +0800 |
|---|---|---|
| committer |   Daniel Vetter <daniel.vetter@ffwll.ch> | 2021-08-05 12:08:15 +0200 |
| commit | 649839d7cf978f08377ba6486c46683d09a3e05d (patch) | |
| tree | ff25e707e89e7905e6392380c5c3c5e20a744e37 | |
| parent | locking/lockdep: Provide lockdep_assert{,_once}() helpers (diff) | |
| download | linux-dev-649839d7cf978f08377ba6486c46683d09a3e05d.tar.xz linux-dev-649839d7cf978f08377ba6486c46683d09a3e05d.zip | |
drm: add lockdep assert to drm_is_current_master_locked
In drm_is_current_master_locked, accessing drm_file.master should be
protected by either drm_file.master_lookup_lock or
drm_device.master_mutex. This was previously awkward to assert with
lockdep.
Following patch ("locking/lockdep: Provide lockdep_assert{,_once}()
helpers"), this assertion is now convenient. So we add in the
assertion and explain this lock design in the kerneldoc.
Signed-off-by: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>
Acked-by: Boqun Feng <boqun.feng@gmail.com>
Acked-by: Waiman Long <longman@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210802105957.77692-3-desmondcheongzx@gmail.com
| -rw-r--r-- | drivers/gpu/drm/drm_auth.c | 6 | ||||
| -rw-r--r-- | include/drm/drm_file.h | 4 |
2 files changed, 7 insertions, 3 deletions
diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c index 53e58bbb6cf5..60a6b21474b1 100644 --- a/drivers/gpu/drm/drm_auth.c +++ b/drivers/gpu/drm/drm_auth.c @@ -63,9 +63,9 @@ static bool drm_is_current_master_locked(struct drm_file *fpriv) { - /* Either drm_device.master_mutex or drm_file.master_lookup_lock - * should be held here. - */ + lockdep_assert_once(lockdep_is_held(&fpriv->master_lookup_lock) || + lockdep_is_held(&fpriv->minor->dev->master_mutex)); + return fpriv->is_master && drm_lease_owner(fpriv->master) == fpriv->minor->dev->master; } diff --git a/include/drm/drm_file.h b/include/drm/drm_file.h index 726cfe0ff5f5..a3acb7ac3550 100644 --- a/include/drm/drm_file.h +++ b/include/drm/drm_file.h @@ -233,6 +233,10 @@ struct drm_file { * this only matches &drm_device.master if the master is the currently * active one. * + * To update @master, both &drm_device.master_mutex and + * @master_lookup_lock need to be held, therefore holding either of + * them is safe and enough for the read side. + * * When dereferencing this pointer, either hold struct * &drm_device.master_mutex for the duration of the pointer's use, or * use drm_file_get_master() if struct &drm_device.master_mutex is not |