net/can: deliver data into multiple CAN conn bound to same dev

Because CAN is a broadcast protocol, each conn needs to be given independent data to avoid mutual interference.

Signed-off-by: zhanghongyu <zhanghongyu@xiaomi.com>

net/can/can.h

@@ -184,6 +184,25 @@ void can_free(FAR struct can_conn_s *conn);
 
 FAR struct can_conn_s *can_nextconn(FAR struct can_conn_s *conn);
 
+/****************************************************************************
+ * Name: can_active()
+ *
+ * Description:
+ *   Traverse the list of NetLink connections that match dev
+ *
+ * Input Parameters:
+ *   dev  - The device to search for.
+ *   conn - The current connection; may be NULL to start the search at the
+ *          beginning
+ *
+ * Assumptions:
+ *   This function is called from NetLink device logic.
+ *
+ ****************************************************************************/
+
+FAR struct can_conn_s *can_active(FAR struct net_driver_s *dev,
+                                  FAR struct can_conn_s *conn);
+
 /****************************************************************************
  * Name: can_callback
  *

net/can/can_conn.c

@@ -225,4 +225,34 @@ FAR struct can_conn_s *can_nextconn(FAR struct can_conn_s *conn)
     }
 }
 
+/****************************************************************************
+ * Name: can_active()
+ *
+ * Description:
+ *   Traverse the list of NetLink connections that match dev
+ *
+ * Input Parameters:
+ *   dev  - The device to search for.
+ *   conn - The current connection; may be NULL to start the search at the
+ *          beginning
+ *
+ * Assumptions:
+ *   This function is called from NetLink device logic.
+ *
+ ****************************************************************************/
+
+FAR struct can_conn_s *can_active(FAR struct net_driver_s *dev,
+                                  FAR struct can_conn_s *conn)
+{
+  while ((conn = can_nextconn(conn)) != NULL)
+    {
+      if (conn->dev == NULL || conn->dev == dev)
+        {
+          break;
+        }
+    }
+
+  return conn;
+}
+
 #endif /* CONFIG_NET_CAN */

net/can/can_input.c

@@ -127,6 +127,67 @@ const uint8_t len_to_can_dlc[65] =
     15,
 };
 
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: can_input_conn
+ *
+ * Description:
+ *   Handle incoming packet input
+ *
+ * Input Parameters:
+ *   dev  - The device driver structure containing the received packet
+ *   conn - A pointer to the CAN connection structure
+ *
+ * Returned Value:
+ *   OK     The packet has been processed  and can be deleted
+ *  -EAGAIN There is a matching connection, but could not dispatch the packet
+ *          yet.  Useful when a packet arrives before a recv call is in
+ *          place.
+ *
+ * Assumptions:
+ *   This function can be called from an interrupt.
+ *
+ ****************************************************************************/
+
+static int can_input_conn(FAR struct net_driver_s *dev,
+                          FAR struct can_conn_s *conn)
+{
+  uint16_t flags;
+  uint16_t buflen = dev->d_len;
+  int ret = OK;
+
+  /* Setup for the application callback */
+
+  dev->d_appdata = dev->d_buf;
+  dev->d_sndlen  = 0;
+  dev->d_len     = buflen;
+
+  /* Perform the application callback */
+
+  flags = can_callback(dev, conn, CAN_NEWDATA);
+
+  /* If the operation was successful, the CAN_NEWDATA flag is removed
+   * and thus the packet can be deleted (OK will be returned).
+   */
+
+  if ((flags & CAN_NEWDATA) != 0)
+    {
+      /* No.. the packet was not processed now.  Return -EAGAIN so
+       * that the driver may retry again later.  We still need to
+       * set d_len to zero so that the driver is aware that there
+       * is nothing to be sent.
+       */
+
+      nwarn("WARNING: Packet not processed\n");
+      ret = -EAGAIN;
+    }
+
+  return ret;
+}
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -151,50 +212,36 @@ const uint8_t len_to_can_dlc[65] =
  *
  ****************************************************************************/
 
-static int can_in(struct net_driver_s *dev)
+static int can_in(FAR struct net_driver_s *dev)
 {
-  FAR struct can_conn_s *conn = NULL;
+  FAR struct can_conn_s *conn = can_active(dev, NULL);
-  int ret = OK;
+  FAR struct can_conn_s *nextconn;
-  uint16_t buflen = dev->d_len;
 
-  do
+  /* Do we have second connection that can hold this packet? */
+
+  while ((nextconn = can_active(dev, conn)) != NULL)
     {
-      conn = can_nextconn(conn);
+      /* Yes... There are multiple listeners on the same dev.
+       * We need to clone the packet and deliver it to each listener.
+       */
 
-      if (conn && (conn->dev == NULL || dev == conn->dev))
+      FAR struct iob_s *iob = netdev_iob_clone(dev, false);
+
+      if (iob == NULL)
         {
-          uint16_t flags;
+          nerr("ERROR: IOB clone failed.\n");
-
+          break; /* We can still process one time without clone. */
-          /* Setup for the application callback */
-
-          dev->d_appdata = dev->d_buf;
-          dev->d_sndlen  = 0;
-          dev->d_len     = buflen;
-
-          /* Perform the application callback */
-
-          flags = can_callback(dev, conn, CAN_NEWDATA);
-
-          /* If the operation was successful, the CAN_NEWDATA flag is removed
-           * and thus the packet can be deleted (OK will be returned).
-           */
-
-          if ((flags & CAN_NEWDATA) != 0)
-            {
-              /* No.. the packet was not processed now.  Return -EAGAIN so
-               * that the driver may retry again later.  We still need to
-               * set d_len to zero so that the driver is aware that there
-               * is nothing to be sent.
-               */
-
-               nwarn("WARNING: Packet not processed\n");
-               ret = -EAGAIN;
-            }
         }
-    }
-  while (conn);
 
-  return ret;
+      can_input_conn(dev, conn);
+
+      netdev_iob_replace(dev, iob);
+      conn = nextconn;
+    }
+
+  /* We can deliver the packet directly to the last listener. */
+
+  return can_input_conn(dev, conn);
 }
 
 /****************************************************************************