drm/atomic: Don't overrun the connector array when hotplugging

[firefly-linux-kernel-4.4.55.git] / drivers / gpu / drm / drm_atomic.c

diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index 67c1dc894bd91670b270122dbbde4ed2756402b1..3624632084e26daeb8fa4210b9460d0b056ee425 100644 (file)
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -56,6 +56,8 @@ drm_atomic_state_alloc(struct drm_device *dev)
        if (!state)
                return NULL;
 
+       state->num_connector = ACCESS_ONCE(dev->mode_config.num_connector);
+
        state->crtcs = kcalloc(dev->mode_config.num_crtc,
                               sizeof(*state->crtcs), GFP_KERNEL);
        if (!state->crtcs)
@@ -72,12 +74,12 @@ drm_atomic_state_alloc(struct drm_device *dev)
                                      sizeof(*state->plane_states), GFP_KERNEL);
        if (!state->plane_states)
                goto fail;
-       state->connectors = kcalloc(dev->mode_config.num_connector,
+       state->connectors = kcalloc(state->num_connector,
                                    sizeof(*state->connectors),
                                    GFP_KERNEL);
        if (!state->connectors)
                goto fail;
-       state->connector_states = kcalloc(dev->mode_config.num_connector,
+       state->connector_states = kcalloc(state->num_connector,
                                          sizeof(*state->connector_states),
                                          GFP_KERNEL);
        if (!state->connector_states)
@@ -117,7 +119,7 @@ void drm_atomic_state_clear(struct drm_atomic_state *state)
 
        DRM_DEBUG_KMS("Clearing atomic state %p\n", state);
 
-       for (i = 0; i < config->num_connector; i++) {
+       for (i = 0; i < state->num_connector; i++) {
                struct drm_connector *connector = state->connectors[i];
 
                if (!connector)
@@ -304,6 +306,21 @@ drm_atomic_get_connector_state(struct drm_atomic_state *state,
 
        index = drm_connector_index(connector);
 
+       /*
+        * Construction of atomic state updates can race with a connector
+        * hot-add which might overflow. In this case flip the table and just
+        * restart the entire ioctl - no one is fast enough to livelock a cpu
+        * with physical hotplug events anyway.
+        *
+        * Note that we only grab the indexes once we have the right lock to
+        * prevent hotplug/unplugging of connectors. So removal is no problem,
+        * at most the array is a bit too large.
+        */
+       if (index >= state->num_connector) {
+               DRM_DEBUG_KMS("Hot-added connector would overflow state array, restarting\n");
+               return -EAGAIN;
+       }
+
        if (state->connector_states[index])
                return state->connector_states[index];
 
@@ -499,10 +516,9 @@ int
 drm_atomic_connectors_for_crtc(struct drm_atomic_state *state,
                               struct drm_crtc *crtc)
 {
-       int nconnectors = state->dev->mode_config.num_connector;
        int i, num_connected_connectors = 0;
 
-       for (i = 0; i < nconnectors; i++) {
+       for (i = 0; i < state->num_connector; i++) {
                struct drm_connector_state *conn_state;
 
                conn_state = state->connector_states[i];