soundwire: stream: fix memory leak in stream config error path

When stream config is failed, master runtime will release all
slave runtime in the slave_rt_list, but slave runtime is not
added to the list at this time. This patch frees slave runtime
in the config error path to fix the memory leak.

Fixes: 89e590535f ("soundwire: Add support for SoundWire stream management")
Signed-off-by: Rander Wang <rander.wang@intel.com>
Reviewed-by: Keyon Jie <yang.jie@intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Link: https://lore.kernel.org/r/20210331004610.12242-1-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/soundwire/stream.c

@@ -1375,8 +1375,16 @@ int sdw_stream_add_slave(struct sdw_slave *slave,
 	}
 
 	ret = sdw_config_stream(&slave->dev, stream, stream_config, true);
-	if (ret)
+	if (ret) {
+		/*
+		 * sdw_release_master_stream will release s_rt in slave_rt_list in
+		 * stream_error case, but s_rt is only added to slave_rt_list
+		 * when sdw_config_stream is successful, so free s_rt explicitly
+		 * when sdw_config_stream is failed.
+		 */
+		kfree(s_rt);
 		goto stream_error;
+	}
 
 	list_add_tail(&s_rt->m_rt_node, &m_rt->slave_rt_list);