idc: zephyr: Fix race between IDC p4wq worker and new msg submission

A race exists between submitting a new IDC message and completion
of a IDC previous message. The completion is handled on another
core in the core's p4wq worker thread.

Add a check to idc_send_msg() to check whether previous message
to target core has been completed, and if it's not done, add a blocking
wait even for nonblocking messages.

Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>

Author: kv2019i

src/idc/zephyr_idc.c

@@ -59,9 +59,16 @@ void idc_init_thread(void)
 K_P4WQ_ARRAY_DEFINE(q_zephyr_idc, CONFIG_CORE_COUNT, SOF_STACK_SIZE,
 		    K_P4WQ_USER_CPU_MASK);
 
+enum {
+	WORK_INIT = 0,
+	WORK_SUBMITTED,
+	WORK_DONE
+};
+
 struct zephyr_idc_msg {
 	struct k_p4wq_work work;
 	struct idc_msg msg;
+	int work_status;
 };
 
 static void idc_handler(struct k_p4wq_work *work)
@@ -101,6 +108,8 @@ static void idc_handler(struct k_p4wq_work *work)
 		ipc_complete_cmd(ipc);
 		k_spin_unlock(&ipc->lock, key);
 	}
+
+	zmsg->work_status = WORK_DONE;
 }
 
 /*
@@ -120,6 +129,18 @@ int idc_send_msg(struct idc_msg *msg, uint32_t mode)
 	int ret;
 	int idc_send_memcpy_err __unused;
 
+	if (!cpu_is_core_enabled(target_cpu)) {
+		tr_err(&zephyr_idc_tr, "Core %u is down, cannot sent IDC message", target_cpu);
+		return -EACCES;
+	}
+
+	if (zmsg->work_status == WORK_SUBMITTED) {
+		work->sync = 1;
+		ret = k_p4wq_wait(work, K_USEC(IDC_TIMEOUT));
+		if (ret < 0 && zmsg->work_status == WORK_SUBMITTED)
+			return ret;
+	}
+
 	idc_send_memcpy_err = memcpy_s(msg_cp, sizeof(*msg_cp), msg, sizeof(*msg));
 	assert(!idc_send_memcpy_err);
 	/* Same priority as the IPC thread which is an EDF task and under Zephyr */
@@ -128,10 +149,8 @@ int idc_send_msg(struct idc_msg *msg, uint32_t mode)
 	work->handler = idc_handler;
 	work->sync = mode == IDC_BLOCKING;
 
-	if (!cpu_is_core_enabled(target_cpu)) {
-		tr_err(&zephyr_idc_tr, "Core %u is down, cannot sent IDC message", target_cpu);
-		return -EACCES;
-	}
+	zmsg->work_status = WORK_SUBMITTED;
+
 	if (msg->payload) {
 		idc_send_memcpy_err = memcpy_s(payload->data, sizeof(payload->data),
 					       msg->payload, msg->size);