channel: Fix topology API locking.

* ast_channel_request_stream_topology_change() must not be called with any
channel locks held.

* ast_channel_stream_topology_changed() must be called with only the
passed channel lock held.

ASTERISK-27212

Change-Id: I843de7956d9f1cc7cc02025aea3463d8fe19c691

include/asterisk/channel.h

@@ -4934,7 +4934,7 @@ int ast_channel_is_multistream(struct ast_channel *chan);
  * \param topology The new stream topology
  * \param change_source The source that initiated the change
  *
- * \pre chan is locked
+ * \note Absolutely _NO_ channel locks should be held before calling this function.
  *
  * \retval 0 request has been accepted to be attempted
  * \retval -1 request could not be attempted
@@ -4956,7 +4956,7 @@ int ast_channel_request_stream_topology_change(struct ast_channel *chan,
  * \param chan The channel to provide notice to
  * \param topology The new stream topology
  *
- * \pre chan is locked
+ * \pre chan is locked  Absolutely _NO_ other channels can be locked.
  *
  * \retval 0 success
  * \retval -1 failure

main/channel.c

@@ -10843,22 +10843,29 @@ enum ast_channel_error ast_channel_errno(void)
 int ast_channel_request_stream_topology_change(struct ast_channel *chan,
 		struct ast_stream_topology *topology, void *change_source)
 {
+	int res;
+
 	ast_assert(chan != NULL);
 	ast_assert(topology != NULL);
 
+	ast_channel_lock(chan);
 	if (!ast_channel_is_multistream(chan) || !ast_channel_tech(chan)->indicate) {
+		ast_channel_unlock(chan);
 		return -1;
 	}
 
 	if (ast_stream_topology_equal(ast_channel_get_stream_topology(chan), topology)) {
 		ast_debug(3, "Topology of %s already matches what is requested so ignoring topology change request\n",
 				ast_channel_name(chan));
+		ast_channel_unlock(chan);
 		return 0;
 	}
 
 	ast_channel_internal_set_stream_topology_change_source(chan, change_source);
 
-	return ast_channel_tech(chan)->indicate(chan, AST_CONTROL_STREAM_TOPOLOGY_REQUEST_CHANGE, topology, sizeof(topology));
+	res = ast_channel_tech(chan)->indicate(chan, AST_CONTROL_STREAM_TOPOLOGY_REQUEST_CHANGE, topology, sizeof(topology));
+	ast_channel_unlock(chan);
+	return res;
 }
 
 int ast_channel_stream_topology_changed(struct ast_channel *chan, struct ast_stream_topology *topology)

tests/test_stream.c

@@ -1768,7 +1768,9 @@ AST_TEST_DEFINE(stream_topology_change_request_from_application_non_multistream)
 	ast_test_validate_cleanup(test, change_res == -1, res, done);
 	ast_test_validate_cleanup(test, !pvt->indicated_change_request, res, done);
 
+	ast_channel_lock(mock_channel);
 	change_res = ast_channel_stream_topology_changed(mock_channel, topology);
+	ast_channel_unlock(mock_channel);
 
 	ast_test_validate_cleanup(test, change_res == -1, res, done);
 	ast_test_validate_cleanup(test, !pvt->indicated_changed, res, done);
@@ -1876,7 +1878,9 @@ AST_TEST_DEFINE(stream_topology_change_request_from_application)
 	ast_test_validate_cleanup(test, !change_res, res, done);
 	ast_test_validate_cleanup(test, pvt->indicated_change_request, res, done);
 
+	ast_channel_lock(mock_channel);
 	change_res = ast_channel_stream_topology_changed(mock_channel, topology);
+	ast_channel_unlock(mock_channel);
 
 	ast_test_validate_cleanup(test, !change_res, res, done);
 	ast_test_validate_cleanup(test, pvt->indicated_changed, res, done);