drm/atomic: Allow for holes in connector state, v2.

Because we record connector_mask using 1 << drm_connector_index now
the connector_mask should stay the same even when other connectors
are removed. This was not the case with MST, in that case when removing
a connector all other connectors may change their index.

This is fixed by waiting until the first get_connector_state to allocate
connector_state, and force reallocation when state is too small.

As a side effect connector arrays no longer have to be preallocated,
and can be allocated on first use which means a less allocations in
the page flip only path.

Changes since v1:
- Whitespace. (Ville)
- Call ida_remove when destroying the connector. (Ville)
- u32 alloc -> int. (Ville)

Fixes: 14de6c44d149 ("drm/atomic: Remove drm_atomic_connectors_for_crtc.")
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Lyude <cpaul@redhat.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/drm_atomic.c

@@ -65,8 +65,6 @@ drm_atomic_state_init(struct drm_device *dev, struct drm_atomic_state *state)
 	 */
 	state->allow_modeset = true;
 
-	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)
@@ -83,16 +81,6 @@ drm_atomic_state_init(struct drm_device *dev, struct drm_atomic_state *state)
 				      sizeof(*state->plane_states), GFP_KERNEL);
 	if (!state->plane_states)
 		goto fail;
-	state->connectors = kcalloc(state->num_connector,
-				    sizeof(*state->connectors),
-				    GFP_KERNEL);
-	if (!state->connectors)
-		goto fail;
-	state->connector_states = kcalloc(state->num_connector,
-					  sizeof(*state->connector_states),
-					  GFP_KERNEL);
-	if (!state->connector_states)
-		goto fail;
 
 	state->dev = dev;
 
@@ -823,19 +811,27 @@ 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_ATOMIC("Hot-added connector would overflow state array, restarting\n");
-		return ERR_PTR(-EAGAIN);
+		struct drm_connector **c;
+		struct drm_connector_state **cs;
+		int alloc = max(index + 1, config->num_connector);
+
+		c = krealloc(state->connectors, alloc * sizeof(*state->connectors), GFP_KERNEL);
+		if (!c)
+			return ERR_PTR(-ENOMEM);
+
+		state->connectors = c;
+		memset(&state->connectors[state->num_connector], 0,
+		       sizeof(*state->connectors) * (alloc - state->num_connector));
+
+		cs = krealloc(state->connector_states, alloc * sizeof(*state->connector_states), GFP_KERNEL);
+		if (!cs)
+			return ERR_PTR(-ENOMEM);
+
+		state->connector_states = cs;
+		memset(&state->connector_states[state->num_connector], 0,
+		       sizeof(*state->connector_states) * (alloc - state->num_connector));
+		state->num_connector = alloc;
 	}
 
 	if (state->connector_states[index])

drivers/gpu/drm/drm_atomic_helper.c

@@ -1493,7 +1493,7 @@ void drm_atomic_helper_swap_state(struct drm_device *dev,
 {
 	int i;
 
-	for (i = 0; i < dev->mode_config.num_connector; i++) {
+	for (i = 0; i < state->num_connector; i++) {
 		struct drm_connector *connector = state->connectors[i];
 
 		if (!connector)

drivers/gpu/drm/drm_crtc.c

@@ -918,12 +918,19 @@ int drm_connector_init(struct drm_device *dev,
 	connector->base.properties = &connector->properties;
 	connector->dev = dev;
 	connector->funcs = funcs;
+
+	connector->connector_id = ida_simple_get(&config->connector_ida, 0, 0, GFP_KERNEL);
+	if (connector->connector_id < 0) {
+		ret = connector->connector_id;
+		goto out_put;
+	}
+
 	connector->connector_type = connector_type;
 	connector->connector_type_id =
 		ida_simple_get(connector_ida, 1, 0, GFP_KERNEL);
 	if (connector->connector_type_id < 0) {
 		ret = connector->connector_type_id;
-		goto out_put;
+		goto out_put_id;
 	}
 	connector->name =
 		kasprintf(GFP_KERNEL, "%s-%d",
@@ -931,7 +938,7 @@ int drm_connector_init(struct drm_device *dev,
 			  connector->connector_type_id);
 	if (!connector->name) {
 		ret = -ENOMEM;
-		goto out_put;
+		goto out_put_type_id;
 	}
 
 	INIT_LIST_HEAD(&connector->probed_modes);
@@ -959,7 +966,12 @@ int drm_connector_init(struct drm_device *dev,
 	}
 
 	connector->debugfs_entry = NULL;
-
+out_put_type_id:
+	if (ret)
+		ida_remove(connector_ida, connector->connector_type_id);
+out_put_id:
+	if (ret)
+		ida_remove(&config->connector_ida, connector->connector_id);
 out_put:
 	if (ret)
 		drm_mode_object_put(dev, &connector->base);
@@ -996,6 +1008,9 @@ void drm_connector_cleanup(struct drm_connector *connector)
 	ida_remove(&drm_connector_enum_list[connector->connector_type].ida,
 		   connector->connector_type_id);
 
+	ida_remove(&dev->mode_config.connector_ida,
+		   connector->connector_id);
+
 	kfree(connector->display_info.bus_formats);
 	drm_mode_object_put(dev, &connector->base);
 	kfree(connector->name);
@@ -1012,32 +1027,6 @@ void drm_connector_cleanup(struct drm_connector *connector)
 }
 EXPORT_SYMBOL(drm_connector_cleanup);
 
-/**
- * drm_connector_index - find the index of a registered connector
- * @connector: connector to find index for
- *
- * Given a registered connector, return the index of that connector within a DRM
- * device's list of connectors.
- */
-unsigned int drm_connector_index(struct drm_connector *connector)
-{
-	unsigned int index = 0;
-	struct drm_connector *tmp;
-	struct drm_mode_config *config = &connector->dev->mode_config;
-
-	WARN_ON(!drm_modeset_is_locked(&config->connection_mutex));
-
-	drm_for_each_connector(tmp, connector->dev) {
-		if (tmp == connector)
-			return index;
-
-		index++;
-	}
-
-	BUG();
-}
-EXPORT_SYMBOL(drm_connector_index);
-
 /**
  * drm_connector_register - register a connector
  * @connector: the connector to register
@@ -5789,6 +5778,7 @@ void drm_mode_config_init(struct drm_device *dev)
 	INIT_LIST_HEAD(&dev->mode_config.plane_list);
 	idr_init(&dev->mode_config.crtc_idr);
 	idr_init(&dev->mode_config.tile_idr);
+	ida_init(&dev->mode_config.connector_ida);
 
 	drm_modeset_lock_all(dev);
 	drm_mode_create_standard_properties(dev);
@@ -5869,6 +5859,7 @@ void drm_mode_config_cleanup(struct drm_device *dev)
 		crtc->funcs->destroy(crtc);
 	}
 
+	ida_destroy(&dev->mode_config.connector_ida);
 	idr_destroy(&dev->mode_config.tile_idr);
 	idr_destroy(&dev->mode_config.crtc_idr);
 	drm_modeset_lock_fini(&dev->mode_config.connection_mutex);

include/drm/drm_crtc.h

@@ -1166,6 +1166,7 @@ struct drm_connector {
 	struct drm_mode_object base;
 
 	char *name;
+	int connector_id;
 	int connector_type;
 	int connector_type_id;
 	bool interlace_allowed;
@@ -2047,6 +2048,7 @@ struct drm_mode_config {
 	struct list_head fb_list;
 
 	int num_connector;
+	struct ida connector_ida;
 	struct list_head connector_list;
 	int num_encoder;
 	struct list_head encoder_list;
@@ -2200,7 +2202,11 @@ int drm_connector_register(struct drm_connector *connector);
 void drm_connector_unregister(struct drm_connector *connector);
 
 extern void drm_connector_cleanup(struct drm_connector *connector);
-extern unsigned int drm_connector_index(struct drm_connector *connector);
+static inline unsigned drm_connector_index(struct drm_connector *connector)
+{
+	return connector->connector_id;
+}
+
 /* helper to unplug all connectors from sysfs for device */
 extern void drm_connector_unplug_all(struct drm_device *dev);