can: add can_free_echo_skb() for upcoming drivers

This patch adds the function can_free_echo_skb to the CAN
device interface to allow upcoming drivers to release echo
skb's in case of error.

Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 18 insertions, 1 deletions

diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c
index 1d29082d94ac..f0b9a1e1db46 100644
--- a/drivers/net/can/dev.c
+++ b/drivers/net/can/dev.c
@@ -315,7 +315,7 @@ void can_get_echo_skb(struct net_device *dev, int idx)
 {
         struct can_priv *priv = netdev_priv(dev);
 
-        if ((dev->flags & IFF_ECHO) && priv->echo_skb[idx]) {
+        if (priv->echo_skb[idx]) {
                 netif_rx(priv->echo_skb[idx]);
                 priv->echo_skb[idx] = NULL;
         }
@@ -323,6 +323,22 @@ void can_get_echo_skb(struct net_device *dev, int idx)
 EXPORT_SYMBOL_GPL(can_get_echo_skb);
 
 /*
+  * Remove the skb from the stack and free it.
+  *
+  * The function is typically called when TX failed.
+  */
+void can_free_echo_skb(struct net_device *dev, int idx)
+{
+        struct can_priv *priv = netdev_priv(dev);
+
+        if (priv->echo_skb[idx]) {
+                kfree_skb(priv->echo_skb[idx]);
+                priv->echo_skb[idx] = NULL;
+        }
+}
+EXPORT_SYMBOL_GPL(can_free_echo_skb);
+
+/*
  * CAN device restart for bus-off recovery
  */
 void can_restart(unsigned long data)
diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h
index 4a37a56f6cdd..5824b20b5fcb 100644
--- a/include/linux/can/dev.h
+++ b/include/linux/can/dev.h
@@ -66,5 +66,6 @@ void can_bus_off(struct net_device *dev);
 
 void can_put_echo_skb(struct sk_buff *skb, struct net_device *dev, int idx);
 void can_get_echo_skb(struct net_device *dev, int idx);
+void can_free_echo_skb(struct net_device *dev, int idx);
 
 #endif /* CAN_DEV_H */