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| author | Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com> | 2021-08-02 12:59:57 +0200 |
|---|---|---|
| committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2021-08-05 12:08:15 +0200 |
| commit | 649839d7cf978f08377ba6486c46683d09a3e05d (patch) | |
| tree | ff25e707e89e7905e6392380c5c3c5e20a744e37 /include/drm/drm_file.h | |
| parent | locking/lockdep: Provide lockdep_assert{,_once}() helpers (diff) | |
| download | linux-649839d7cf978f08377ba6486c46683d09a3e05d.tar.xz linux-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
Diffstat (limited to 'include/drm/drm_file.h')
| -rw-r--r-- | include/drm/drm_file.h | 4 |
1 files changed, 4 insertions, 0 deletions
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 |