Bluetooth: host: sched-lock bt_recv()

`bt_recv` is invoked from the BT long work queue, which is preemptible.
The host uses cooperative scheduling to ensure thread safety.

Signed-off-by: Aleksander Wasaznik <[email protected]>

drivers/bluetooth/hci/ipc.c

@@ -229,19 +229,7 @@ static void bt_ipc_rx(const uint8_t *data, size_t len)
 
 	if (buf) {
 		LOG_DBG("Calling bt_recv(%p)", buf);
-
-		/* The IPC service does not guarantee that the handler thread
-		 * is cooperative. In particular, the OpenAMP implementation is
-		 * preemtible by default. OTOH, the HCI driver interface requires
-		 * that the bt_recv() function is called from a cooperative
-		 * thread.
-		 *
-		 * Calling `k_sched lock()` has the effect of making the current
-		 * thread cooperative.
-		 */
-		k_sched_lock();
 		bt_recv(buf);
-		k_sched_unlock();
 
 		LOG_HEXDUMP_DBG(buf->data, buf->len, "RX buf payload:");
 	}

include/zephyr/drivers/bluetooth/hci_driver.h

@@ -89,8 +89,6 @@ static inline uint8_t bt_hci_evt_get_flags(uint8_t evt)
  * for so-called high priority HCI events, which should instead be delivered to
  * the host stack through bt_recv_prio().
  *
- * @note This function must only be called from a cooperative thread.
- *
  * @param buf Network buffer containing data from the controller.
  *
  * @return 0 on success or negative error number on failure.

subsys/bluetooth/host/hci_core.c

@@ -3854,7 +3854,7 @@ static void rx_queue_put(struct net_buf *buf)
 }
 #endif /* !CONFIG_BT_RECV_BLOCKING */
 
-int bt_recv(struct net_buf *buf)
+static int bt_recv_unsafe(struct net_buf *buf)
 {
 	bt_monitor_send(bt_monitor_opcode(buf), buf->data, buf->len);
 
@@ -3905,6 +3905,17 @@ int bt_recv(struct net_buf *buf)
 	}
 }
 
+int bt_recv(struct net_buf *buf)
+{
+	int err;
+
+	k_sched_lock();
+	err = bt_recv_unsafe(buf);
+	k_sched_unlock();
+
+	return err;
+}
+
 int bt_recv_prio(struct net_buf *buf)
 {
 	bt_monitor_send(bt_monitor_opcode(buf), buf->data, buf->len);