drm/atomic: Check for busy planes/connectors before setting the commit

We still want to fail with -EBUSY if a plane or connector is part of
a commit, even if it will be assigned to a new commit.

This closes a small hole left open where we should return -EBUSY.
It's not severe, because wait_for_dependencies and swap_state helpers
still block. But it should return -EBUSY and not stall.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Fixes: 21a01abbe32a ("drm/atomic: Fix freeing connector/plane state too early by tracking commits, v3.")
Link: https://patchwork.freedesktop.org/patch/msgid/20171016132928.6498-2-maarten.lankhorst@linux.intel.com
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

1 files changed, 8 insertions, 9 deletions

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index aec73f4c70c6..3472d9ae8b95 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -1772,16 +1772,16 @@ int drm_atomic_helper_setup_commit(struct drm_atomic_state *state,
         }
 
         for_each_oldnew_connector_in_state(state, conn, old_conn_state, new_conn_state, i) {
-                /* commit tracked through new_crtc_state->commit, no need to do it explicitly */
-                if (new_conn_state->crtc)
-                        continue;
-
                 /* Userspace is not allowed to get ahead of the previous
                  * commit with nonblocking ones. */
                 if (nonblock && old_conn_state->commit &&
                     !try_wait_for_completion(&old_conn_state->commit->flip_done))
                         return -EBUSY;
 
+                /* commit tracked through new_crtc_state->commit, no need to do it explicitly */
+                if (new_conn_state->crtc)
+                        continue;
+
                 commit = crtc_or_fake_commit(state, old_conn_state->crtc);
                 if (!commit)
                         return -ENOMEM;
@@ -1790,17 +1790,16 @@ int drm_atomic_helper_setup_commit(struct drm_atomic_state *state,
         }
 
         for_each_oldnew_plane_in_state(state, plane, old_plane_state, new_plane_state, i) {
-                /*
-                 * Unlike connectors, always track planes explicitly for
-                 * async pageflip support.
-                 */
-
                 /* Userspace is not allowed to get ahead of the previous
                  * commit with nonblocking ones. */
                 if (nonblock && old_plane_state->commit &&
                     !try_wait_for_completion(&old_plane_state->commit->flip_done))
                         return -EBUSY;
 
+                /*
+                 * Unlike connectors, always track planes explicitly for
+                 * async pageflip support.
+                 */
                 commit = crtc_or_fake_commit(state, new_plane_state->crtc ?: old_plane_state->crtc);
                 if (!commit)
                         return -ENOMEM;