drm: Implement drm_modeset_lock_all_ctx()

This function is like drm_modeset_lock_all(), but it takes the lock
acquisition context as a parameter rather than storing it in the DRM
device's mode_config structure.

Implement drm_modeset_{,un}lock_all() in terms of the new function for
better code reuse, and add a note to the kerneldoc that new code should
use the new functions.

v2: improve kerneldoc
v4: rename drm_modeset_lock_all_crtcs() to drm_modeset_lock_all_ctx()
    and take mode_config's .connection_mutex instead of .mutex lock to
    avoid lock inversion (Daniel Vetter), use drm_modeset_drop_locks()
    which is now the equivalent of drm_modeset_unlock_all_ctx()
v5: do not take the dev->mode_config.connection_mutex in
    drm_atomic_legacy_backoff() since drm_modeset_lock_all_ctx()
    already keeps it, enhance kerneldoc for drm_modeset_lock_all_ctx()
    (Daniel Vetter)

Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1449075005-13937-1-git-send-email-thierry.reding@gmail.com
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 1 insertions, 6 deletions

diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index 55b4debad79b..ef5f7663a718 100644
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -1188,12 +1188,7 @@ void drm_atomic_legacy_backoff(struct drm_atomic_state *state)
 retry:
 	drm_modeset_backoff(state->acquire_ctx);
 
-	ret = drm_modeset_lock(&state->dev->mode_config.connection_mutex,
-			       state->acquire_ctx);
-	if (ret)
-		goto retry;
-	ret = drm_modeset_lock_all_crtcs(state->dev,
-					 state->acquire_ctx);
+	ret = drm_modeset_lock_all_ctx(state->dev, state->acquire_ctx);
 	if (ret)
 		goto retry;
 }