nvidia-drm: handle -EDEADLK in nv_drm_reset_input_colorspace

drm_atomic_get_plane_state() and drm_atomic_commit() can return -EDEADLK when
ww-mutex deadlock avoidance triggers. The current
nv_drm_reset_input_colorspace() path drops locks and returns without running
the required modeset backoff/retry flow.

Rework the function to retry the atomic sequence with drm_modeset_backoff(&ctx),
rebuilding atomic state on each retry, and only finish once the sequence
succeeds or another error is returned.

Signed-off-by: Paul Moses <p@1g4.org>

Author: jopamo

kernel-open/nvidia-drm/nvidia-drm-drv.c

@@ -937,21 +937,25 @@ int nv_drm_reset_input_colorspace(struct drm_device *dev)
     bool do_reset = false;
     NvU32 flags = 0;
 
-    state = drm_atomic_state_alloc(dev);
-    if (!state)
-        return -ENOMEM;
-
 #if defined(DRM_MODESET_ACQUIRE_INTERRUPTIBLE)
     flags |= DRM_MODESET_ACQUIRE_INTERRUPTIBLE;
 #endif
     drm_modeset_acquire_init(&ctx, flags);
+
+retry:
+    do_reset = false;
+    state = drm_atomic_state_alloc(dev);
+    if (!state) {
+        ret = -ENOMEM;
+        goto out;
+    }
     state->acquire_ctx = &ctx;
 
     nv_drm_for_each_plane(plane, dev) {
         plane_state = drm_atomic_get_plane_state(state, plane);
         if (IS_ERR(plane_state)) {
             ret = PTR_ERR(plane_state);
-            goto out;
+            goto put_state;
         }
 
         nv_drm_plane_state = to_nv_drm_plane_state(plane_state);
@@ -967,8 +971,17 @@ int nv_drm_reset_input_colorspace(struct drm_device *dev)
         ret = drm_atomic_commit(state);
     }
 
-out:
+put_state:
     drm_atomic_state_put(state);
+
+    if (ret == -EDEADLK) {
+        ret = drm_modeset_backoff(&ctx);
+        if (!ret) {
+            goto retry;
+        }
+    }
+
+out:
     drm_modeset_drop_locks(&ctx);
     drm_modeset_acquire_fini(&ctx);
 
@@ -1386,8 +1399,8 @@ nv_drm_atomic_disable_connector(struct drm_atomic_state *state,
     if (nv_connector->modeset_permission_crtc) {
         crtc_state = drm_atomic_get_crtc_state(
             state, &nv_connector->modeset_permission_crtc->base);
-        if (!crtc_state) {
-            return -EINVAL;
+        if (IS_ERR(crtc_state)) {
+            return PTR_ERR(crtc_state);
         }
 
         crtc_state->active = false;
@@ -1398,8 +1411,8 @@ nv_drm_atomic_disable_connector(struct drm_atomic_state *state,
     }
 
     connector_state = drm_atomic_get_connector_state(state, &nv_connector->base);
-    if (!connector_state) {
-        return -EINVAL;
+    if (IS_ERR(connector_state)) {
+        return PTR_ERR(connector_state);
     }
 
     return drm_atomic_set_crtc_for_connector(connector_state, NULL);
@@ -1442,6 +1455,7 @@ static int nv_drm_revoke_modeset_permission(struct drm_device *dev,
             (!dpyId || nv_drm_connector_is_dpy_id(connector, dpyId))) {
             ret = nv_drm_atomic_disable_connector(state, nv_connector);
             if (ret < 0) {
+                drm_connector_list_iter_end(&conn_iter);
                 goto done;
             }
 

kernel-open/nvidia-drm/nvidia-drm-helper.c

@@ -98,9 +98,11 @@ int nv_drm_atomic_helper_disable_all(struct drm_device *dev,
     struct drm_plane *plane;
     struct drm_crtc_state *crtc_state;
     struct drm_crtc *crtc;
-    unsigned plane_mask = 0;
+    unsigned plane_mask;
     int ret, i;
 
+retry:
+    plane_mask = 0;
     state = drm_atomic_state_alloc(dev);
     if (!state)
         return -ENOMEM;
@@ -175,6 +177,12 @@ int nv_drm_atomic_helper_disable_all(struct drm_device *dev,
 
     drm_atomic_state_put(state);
 
+    if (ret == -EDEADLK) {
+        ret = drm_modeset_backoff(ctx);
+        if (!ret)
+            goto retry;
+    }
+
     return ret;
 }