audio: check NULL linked buffer in .trigger()

If .trigger() is wrongly called on a pipeline, that isn't connected
to a DAI, its edge component will hit a NULL buffer, which then has
to be checked.

Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>

Author: lyakh

src/audio/asrc/asrc.c

@@ -452,11 +452,14 @@ static int asrc_dai_find(struct comp_dev *dev, struct comp_data *cd)
 		/* In push mode check if sink component is DAI */
 		do {
 			sinkb = comp_dev_get_first_data_consumer(dev);
+			if (!sinkb) {
+				comp_err(asrc_dev, "At end: NULL buffer, no DAI found.");
+				return -EINVAL;
+			}
 
 			dev = comp_buffer_get_sink_component(sinkb);
-
 			if (!dev) {
-				comp_err(asrc_dev, "At end, no DAI found.");
+				comp_err(asrc_dev, "At end: NULL device, no DAI found.");
 				return -EINVAL;
 			}
 
@@ -470,11 +473,14 @@ static int asrc_dai_find(struct comp_dev *dev, struct comp_data *cd)
 		/* In pull mode check if source component is DAI */
 		do {
 			sourceb = comp_dev_get_first_data_producer(dev);
+			if (!sourceb) {
+				comp_err(asrc_dev, "At beginning: NULL buffer, no DAI found.");
+				return -EINVAL;
+			}
 
 			dev = comp_buffer_get_source_component(sourceb);
-
 			if (!dev) {
-				comp_err(asrc_dev, "At beginning, no DAI found.");
+				comp_err(asrc_dev, "At beginning: NULL device, no DAI found.");
 				return -EINVAL;
 			}
 

src/audio/selector/selector.c

@@ -344,8 +344,14 @@ static int selector_trigger(struct comp_dev *dev, int cmd)
 	comp_dbg(dev, "selector_trigger()");
 
 	sourceb = comp_dev_get_first_data_producer(dev);
+	if (!sourceb) {
+		comp_err(dev, "source disconnected");
+		return -ENODEV;
+	}
 
 	ret = comp_set_state(dev, cmd);
+	if (ret == COMP_STATUS_STATE_ALREADY_SET)
+		ret = 0;
 
 	/* TODO: remove in the future after adding support for case when
 	 * kpb_init_draining() and kpb_draining_task() are interrupted by