can: dev: can_get_echo_skb(): factor out non sending code to __can_get_echo_skb()

This patch factors out all non sending parts of can_get_echo_skb() into
a seperate function __can_get_echo_skb(), so that it can be re-used in
an upcoming patch.

Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/dev.c

@@ -477,14 +477,7 @@ void can_put_echo_skb(struct sk_buff *skb, struct net_device *dev,
 }
 EXPORT_SYMBOL_GPL(can_put_echo_skb);
 
-/*
- * Get the skb from the stack and loop it back locally
- *
- * The function is typically called when the TX done interrupt
- * is handled in the device driver. The driver must protect
- * access to priv->echo_skb, if necessary.
- */
-unsigned int can_get_echo_skb(struct net_device *dev, unsigned int idx)
+struct sk_buff *__can_get_echo_skb(struct net_device *dev, unsigned int idx, u8 *len_ptr)
 {
 	struct can_priv *priv = netdev_priv(dev);
 
@@ -495,13 +488,34 @@ unsigned int can_get_echo_skb(struct net_device *dev, unsigned int idx)
 		struct can_frame *cf = (struct can_frame *)skb->data;
 		u8 dlc = cf->can_dlc;
 
-		netif_rx(priv->echo_skb[idx]);
+		*len_ptr = dlc;
 		priv->echo_skb[idx] = NULL;
 
-		return dlc;
+		return skb;
 	}
 
-	return 0;
+	return NULL;
+}
+
+/*
+ * Get the skb from the stack and loop it back locally
+ *
+ * The function is typically called when the TX done interrupt
+ * is handled in the device driver. The driver must protect
+ * access to priv->echo_skb, if necessary.
+ */
+unsigned int can_get_echo_skb(struct net_device *dev, unsigned int idx)
+{
+	struct sk_buff *skb;
+	u8 len;
+
+	skb = __can_get_echo_skb(dev, idx, &len);
+	if (!skb)
+		return 0;
+
+	netif_rx(skb);
+
+	return len;
 }
 EXPORT_SYMBOL_GPL(can_get_echo_skb);
 

include/linux/can/dev.h

@@ -169,6 +169,7 @@ void can_change_state(struct net_device *dev, struct can_frame *cf,
 
 void can_put_echo_skb(struct sk_buff *skb, struct net_device *dev,
 		      unsigned int idx);
+struct sk_buff *__can_get_echo_skb(struct net_device *dev, unsigned int idx, u8 *len_ptr);
 unsigned int can_get_echo_skb(struct net_device *dev, unsigned int idx);
 void can_free_echo_skb(struct net_device *dev, unsigned int idx);