pipeline: protect component connections with a mutex

src/audio/buffers/comp_buffer.c

@@ -559,7 +559,8 @@ static inline struct list_item *buffer_comp_list(struct comp_buffer *buffer,
 }
 
 /*
- * Locking: must be called with interrupts disabled! Serialized IPCs protect us
+ * Locking: must be called with interrupts disabled (or sys_mutex held for
+ * userspace LL builds)! Serialized IPCs protect us
  * from racing attach / detach calls, but the scheduler can interrupt the IPC
  * thread and begin using the buffer for streaming. FIXME: this is still a
  * problem with different cores.
@@ -572,7 +573,8 @@ void buffer_attach(struct comp_buffer *buffer, struct list_item *head, int dir)
 }
 
 /*
- * Locking: must be called with interrupts disabled! See buffer_attach() above
+ * Locking: must be called with interrupts disabled (or sys_mutex held for
+ * userspace LL builds)! See buffer_attach() above
  * for details
  */
 void buffer_detach(struct comp_buffer *buffer, struct list_item *head, int dir)

src/audio/pipeline/pipeline-graph.c

@@ -178,45 +178,55 @@ static void buffer_set_comp(struct comp_buffer *buffer, struct comp_dev *comp,
 		comp_buffer_set_sink_component(buffer, comp);
 }
 
+#ifdef CONFIG_SOF_USERSPACE_LL
+#define PPL_LOCK_DECLARE
+#define PPL_LOCK() { int ret = sys_mutex_lock(&comp->list_mutex, K_FOREVER); assert(ret == 0); }
+#define PPL_UNLOCK() { int ret = sys_mutex_unlock(&comp->list_mutex); assert(ret == 0); }
+#else
+#define PPL_LOCK_DECLARE uint32_t flags
+#define PPL_LOCK() irq_local_disable(flags)
+#define PPL_UNLOCK()  irq_local_enable(flags)
+#endif
+
 int pipeline_connect(struct comp_dev *comp, struct comp_buffer *buffer,
 		     int dir)
 {
 	struct list_item *comp_list;
-	uint32_t flags;
+	PPL_LOCK_DECLARE;
 
 	if (dir == PPL_CONN_DIR_COMP_TO_BUFFER)
 		comp_info(comp, "connect buffer %d as sink", buf_get_id(buffer));
 	else
 		comp_info(comp, "connect buffer %d as source", buf_get_id(buffer));
 
-	irq_local_disable(flags);
+	PPL_LOCK();
 
 	comp_list = comp_buffer_list(comp, dir);
 	buffer_attach(buffer, comp_list, dir);
 	buffer_set_comp(buffer, comp, dir);
 
-	irq_local_enable(flags);
+	PPL_UNLOCK();
 
 	return 0;
 }
 
 void pipeline_disconnect(struct comp_dev *comp, struct comp_buffer *buffer, int dir)
 {
 	struct list_item *comp_list;
-	uint32_t flags;
+	PPL_LOCK_DECLARE;
 
 	if (dir == PPL_CONN_DIR_COMP_TO_BUFFER)
 		comp_dbg(comp, "disconnect buffer %d as sink", buf_get_id(buffer));
 	else
 		comp_dbg(comp, "disconnect buffer %d as source", buf_get_id(buffer));
 
-	irq_local_disable(flags);
+	PPL_LOCK();
 
 	comp_list = comp_buffer_list(comp, dir);
 	buffer_detach(buffer, comp_list, dir);
 	buffer_set_comp(buffer, NULL, dir);
 
-	irq_local_enable(flags);
+	PPL_UNLOCK();
 }
 
 /* pipelines must be inactive */

src/include/sof/audio/component.h

@@ -21,6 +21,7 @@
 #include <sof/audio/pipeline.h>
 #include <sof/debug/telemetry/telemetry.h>
 #include <rtos/idc.h>
+#include <rtos/mutex.h>
 #include <rtos/userspace_helper.h>
 #include <sof/lib/dai.h>
 #include <sof/schedule/schedule.h>
@@ -679,6 +680,10 @@ struct comp_dev {
 	struct list_item bsource_list;	/**< list of source buffers */
 	struct list_item bsink_list;	/**< list of sink buffers */
 
+#ifdef CONFIG_SOF_USERSPACE_LL
+	struct sys_mutex list_mutex;     /**< protect lists of source/sinks */
+#endif
+
 	/* performance data*/
 	struct comp_perf_data perf_data;
 	/* Input Buffer Size for pin 0, add array for other pins if needed */
@@ -863,6 +868,9 @@ static inline void comp_init(const struct comp_driver *drv,
 	dev->state = COMP_STATE_INIT;
 	list_init(&dev->bsink_list);
 	list_init(&dev->bsource_list);
+#ifdef CONFIG_SOF_USERSPACE_LL
+	sys_mutex_init(&dev->list_mutex);
+#endif
 	memcpy_s(&dev->tctx, sizeof(dev->tctx),
 		 trace_comp_drv_get_tr_ctx(dev->drv), sizeof(struct tr_ctx));
 }