[net-next v3 05/15] can: dev: move skb related into seperate file

[Marc Kleine-Budde <mkl@pengutronix.de>]

This patch moves the skb related code of the CAN device infrastructure into a
separate file.

Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 drivers/net/can/dev/Makefile |   1 +
 drivers/net/can/dev/dev.c    | 213 ---------------------------------
 drivers/net/can/dev/skb.c    | 220 +++++++++++++++++++++++++++++++++++
 include/linux/can/dev.h      |  76 ------------
 include/linux/can/skb.h      |  77 ++++++++++++
 5 files changed, 298 insertions(+), 289 deletions(-)
 create mode 100644 drivers/net/can/dev/skb.c

diff --git a/drivers/net/can/dev/Makefile b/drivers/net/can/dev/Makefile
index 5c647951e06d..188bd53b113c 100644
--- a/drivers/net/can/dev/Makefile
+++ b/drivers/net/can/dev/Makefile
@@ -5,5 +5,6 @@ can-dev-y			+= bittiming.o
 can-dev-y			+= dev.o
 can-dev-y			+= length.o
 can-dev-y			+= rx-offload.o
+can-dev-y                       += skb.o
 
 can-dev-$(CONFIG_CAN_LEDS)	+= led.o
diff --git a/drivers/net/can/dev/dev.c b/drivers/net/can/dev/dev.c
index 3372e99d5db7..fe71ff9ef8c9 100644
--- a/drivers/net/can/dev/dev.c
+++ b/drivers/net/can/dev/dev.c
@@ -132,149 +132,6 @@ void can_change_state(struct net_device *dev, struct can_frame *cf,
 }
 EXPORT_SYMBOL_GPL(can_change_state);
 
-/* Local echo of CAN messages
- *
- * CAN network devices *should* support a local echo functionality
- * (see Documentation/networking/can.rst). To test the handling of CAN
- * interfaces that do not support the local echo both driver types are
- * implemented. In the case that the driver does not support the echo
- * the IFF_ECHO remains clear in dev->flags. This causes the PF_CAN core
- * to perform the echo as a fallback solution.
- */
-static void can_flush_echo_skb(struct net_device *dev)
-{
-	struct can_priv *priv = netdev_priv(dev);
-	struct net_device_stats *stats = &dev->stats;
-	int i;
-
-	for (i = 0; i < priv->echo_skb_max; i++) {
-		if (priv->echo_skb[i]) {
-			kfree_skb(priv->echo_skb[i]);
-			priv->echo_skb[i] = NULL;
-			stats->tx_dropped++;
-			stats->tx_aborted_errors++;
-		}
-	}
-}
-
-/* Put the skb on the stack to be looped backed locally lateron
- *
- * The function is typically called in the start_xmit function
- * of the device driver. The driver must protect access to
- * priv->echo_skb, if necessary.
- */
-int can_put_echo_skb(struct sk_buff *skb, struct net_device *dev,
-		     unsigned int idx)
-{
-	struct can_priv *priv = netdev_priv(dev);
-
-	BUG_ON(idx >= priv->echo_skb_max);
-
-	/* check flag whether this packet has to be looped back */
-	if (!(dev->flags & IFF_ECHO) || skb->pkt_type != PACKET_LOOPBACK ||
-	    (skb->protocol != htons(ETH_P_CAN) &&
-	     skb->protocol != htons(ETH_P_CANFD))) {
-		kfree_skb(skb);
-		return 0;
-	}
-
-	if (!priv->echo_skb[idx]) {
-		skb = can_create_echo_skb(skb);
-		if (!skb)
-			return -ENOMEM;
-
-		/* make settings for echo to reduce code in irq context */
-		skb->pkt_type = PACKET_BROADCAST;
-		skb->ip_summed = CHECKSUM_UNNECESSARY;
-		skb->dev = dev;
-
-		/* save this skb for tx interrupt echo handling */
-		priv->echo_skb[idx] = skb;
-	} else {
-		/* locking problem with netif_stop_queue() ?? */
-		netdev_err(dev, "%s: BUG! echo_skb %d is occupied!\n", __func__, idx);
-		kfree_skb(skb);
-		return -EBUSY;
-	}
-
-	return 0;
-}
-EXPORT_SYMBOL_GPL(can_put_echo_skb);
-
-struct sk_buff *
-__can_get_echo_skb(struct net_device *dev, unsigned int idx, u8 *len_ptr)
-{
-	struct can_priv *priv = netdev_priv(dev);
-
-	if (idx >= priv->echo_skb_max) {
-		netdev_err(dev, "%s: BUG! Trying to access can_priv::echo_skb out of bounds (%u/max %u)\n",
-			   __func__, idx, priv->echo_skb_max);
-		return NULL;
-	}
-
-	if (priv->echo_skb[idx]) {
-		/* Using "struct canfd_frame::len" for the frame
-		 * length is supported on both CAN and CANFD frames.
-		 */
-		struct sk_buff *skb = priv->echo_skb[idx];
-		struct canfd_frame *cf = (struct canfd_frame *)skb->data;
-
-		/* get the real payload length for netdev statistics */
-		if (cf->can_id & CAN_RTR_FLAG)
-			*len_ptr = 0;
-		else
-			*len_ptr = cf->len;
-
-		priv->echo_skb[idx] = NULL;
-
-		return skb;
-	}
-
-	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;
-
-	skb_get(skb);
-	if (netif_rx(skb) == NET_RX_SUCCESS)
-		dev_consume_skb_any(skb);
-	else
-		dev_kfree_skb_any(skb);
-
-	return len;
-}
-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, unsigned int idx)
-{
-	struct can_priv *priv = netdev_priv(dev);
-
-	BUG_ON(idx >= priv->echo_skb_max);
-
-	if (priv->echo_skb[idx]) {
-		dev_kfree_skb_any(priv->echo_skb[idx]);
-		priv->echo_skb[idx] = NULL;
-	}
-}
-EXPORT_SYMBOL_GPL(can_free_echo_skb);
-
 /* CAN device restart for bus-off recovery */
 static void can_restart(struct net_device *dev)
 {
@@ -379,76 +236,6 @@ static void can_setup(struct net_device *dev)
 	dev->features = NETIF_F_HW_CSUM;
 }
 
-struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf)
-{
-	struct sk_buff *skb;
-
-	skb = netdev_alloc_skb(dev, sizeof(struct can_skb_priv) +
-			       sizeof(struct can_frame));
-	if (unlikely(!skb))
-		return NULL;
-
-	skb->protocol = htons(ETH_P_CAN);
-	skb->pkt_type = PACKET_BROADCAST;
-	skb->ip_summed = CHECKSUM_UNNECESSARY;
-
-	skb_reset_mac_header(skb);
-	skb_reset_network_header(skb);
-	skb_reset_transport_header(skb);
-
-	can_skb_reserve(skb);
-	can_skb_prv(skb)->ifindex = dev->ifindex;
-	can_skb_prv(skb)->skbcnt = 0;
-
-	*cf = skb_put_zero(skb, sizeof(struct can_frame));
-
-	return skb;
-}
-EXPORT_SYMBOL_GPL(alloc_can_skb);
-
-struct sk_buff *alloc_canfd_skb(struct net_device *dev,
-				struct canfd_frame **cfd)
-{
-	struct sk_buff *skb;
-
-	skb = netdev_alloc_skb(dev, sizeof(struct can_skb_priv) +
-			       sizeof(struct canfd_frame));
-	if (unlikely(!skb))
-		return NULL;
-
-	skb->protocol = htons(ETH_P_CANFD);
-	skb->pkt_type = PACKET_BROADCAST;
-	skb->ip_summed = CHECKSUM_UNNECESSARY;
-
-	skb_reset_mac_header(skb);
-	skb_reset_network_header(skb);
-	skb_reset_transport_header(skb);
-
-	can_skb_reserve(skb);
-	can_skb_prv(skb)->ifindex = dev->ifindex;
-	can_skb_prv(skb)->skbcnt = 0;
-
-	*cfd = skb_put_zero(skb, sizeof(struct canfd_frame));
-
-	return skb;
-}
-EXPORT_SYMBOL_GPL(alloc_canfd_skb);
-
-struct sk_buff *alloc_can_err_skb(struct net_device *dev, struct can_frame **cf)
-{
-	struct sk_buff *skb;
-
-	skb = alloc_can_skb(dev, cf);
-	if (unlikely(!skb))
-		return NULL;
-
-	(*cf)->can_id = CAN_ERR_FLAG;
-	(*cf)->len = CAN_ERR_DLC;
-
-	return skb;
-}
-EXPORT_SYMBOL_GPL(alloc_can_err_skb);
-
 /* Allocate and setup space for the CAN network device */
 struct net_device *alloc_candev_mqs(int sizeof_priv, unsigned int echo_skb_max,
 				    unsigned int txqs, unsigned int rxqs)
diff --git a/drivers/net/can/dev/skb.c b/drivers/net/can/dev/skb.c
new file mode 100644
index 000000000000..26cd597ff771
--- /dev/null
+++ b/drivers/net/can/dev/skb.c
@@ -0,0 +1,220 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (C) 2005 Marc Kleine-Budde, Pengutronix
+ * Copyright (C) 2006 Andrey Volkov, Varma Electronics
+ * Copyright (C) 2008-2009 Wolfgang Grandegger <wg@grandegger.com>
+ */
+
+#include <linux/can/dev.h>
+
+/* Local echo of CAN messages
+ *
+ * CAN network devices *should* support a local echo functionality
+ * (see Documentation/networking/can.rst). To test the handling of CAN
+ * interfaces that do not support the local echo both driver types are
+ * implemented. In the case that the driver does not support the echo
+ * the IFF_ECHO remains clear in dev->flags. This causes the PF_CAN core
+ * to perform the echo as a fallback solution.
+ */
+void can_flush_echo_skb(struct net_device *dev)
+{
+	struct can_priv *priv = netdev_priv(dev);
+	struct net_device_stats *stats = &dev->stats;
+	int i;
+
+	for (i = 0; i < priv->echo_skb_max; i++) {
+		if (priv->echo_skb[i]) {
+			kfree_skb(priv->echo_skb[i]);
+			priv->echo_skb[i] = NULL;
+			stats->tx_dropped++;
+			stats->tx_aborted_errors++;
+		}
+	}
+}
+
+/* Put the skb on the stack to be looped backed locally lateron
+ *
+ * The function is typically called in the start_xmit function
+ * of the device driver. The driver must protect access to
+ * priv->echo_skb, if necessary.
+ */
+int can_put_echo_skb(struct sk_buff *skb, struct net_device *dev,
+		     unsigned int idx)
+{
+	struct can_priv *priv = netdev_priv(dev);
+
+	BUG_ON(idx >= priv->echo_skb_max);
+
+	/* check flag whether this packet has to be looped back */
+	if (!(dev->flags & IFF_ECHO) || skb->pkt_type != PACKET_LOOPBACK ||
+	    (skb->protocol != htons(ETH_P_CAN) &&
+	     skb->protocol != htons(ETH_P_CANFD))) {
+		kfree_skb(skb);
+		return 0;
+	}
+
+	if (!priv->echo_skb[idx]) {
+		skb = can_create_echo_skb(skb);
+		if (!skb)
+			return -ENOMEM;
+
+		/* make settings for echo to reduce code in irq context */
+		skb->pkt_type = PACKET_BROADCAST;
+		skb->ip_summed = CHECKSUM_UNNECESSARY;
+		skb->dev = dev;
+
+		/* save this skb for tx interrupt echo handling */
+		priv->echo_skb[idx] = skb;
+	} else {
+		/* locking problem with netif_stop_queue() ?? */
+		netdev_err(dev, "%s: BUG! echo_skb %d is occupied!\n", __func__, idx);
+		kfree_skb(skb);
+		return -EBUSY;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(can_put_echo_skb);
+
+struct sk_buff *
+__can_get_echo_skb(struct net_device *dev, unsigned int idx, u8 *len_ptr)
+{
+	struct can_priv *priv = netdev_priv(dev);
+
+	if (idx >= priv->echo_skb_max) {
+		netdev_err(dev, "%s: BUG! Trying to access can_priv::echo_skb out of bounds (%u/max %u)\n",
+			   __func__, idx, priv->echo_skb_max);
+		return NULL;
+	}
+
+	if (priv->echo_skb[idx]) {
+		/* Using "struct canfd_frame::len" for the frame
+		 * length is supported on both CAN and CANFD frames.
+		 */
+		struct sk_buff *skb = priv->echo_skb[idx];
+		struct canfd_frame *cf = (struct canfd_frame *)skb->data;
+
+		/* get the real payload length for netdev statistics */
+		if (cf->can_id & CAN_RTR_FLAG)
+			*len_ptr = 0;
+		else
+			*len_ptr = cf->len;
+
+		priv->echo_skb[idx] = NULL;
+
+		return skb;
+	}
+
+	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;
+
+	skb_get(skb);
+	if (netif_rx(skb) == NET_RX_SUCCESS)
+		dev_consume_skb_any(skb);
+	else
+		dev_kfree_skb_any(skb);
+
+	return len;
+}
+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, unsigned int idx)
+{
+	struct can_priv *priv = netdev_priv(dev);
+
+	BUG_ON(idx >= priv->echo_skb_max);
+
+	if (priv->echo_skb[idx]) {
+		dev_kfree_skb_any(priv->echo_skb[idx]);
+		priv->echo_skb[idx] = NULL;
+	}
+}
+EXPORT_SYMBOL_GPL(can_free_echo_skb);
+
+struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf)
+{
+	struct sk_buff *skb;
+
+	skb = netdev_alloc_skb(dev, sizeof(struct can_skb_priv) +
+			       sizeof(struct can_frame));
+	if (unlikely(!skb))
+		return NULL;
+
+	skb->protocol = htons(ETH_P_CAN);
+	skb->pkt_type = PACKET_BROADCAST;
+	skb->ip_summed = CHECKSUM_UNNECESSARY;
+
+	skb_reset_mac_header(skb);
+	skb_reset_network_header(skb);
+	skb_reset_transport_header(skb);
+
+	can_skb_reserve(skb);
+	can_skb_prv(skb)->ifindex = dev->ifindex;
+	can_skb_prv(skb)->skbcnt = 0;
+
+	*cf = skb_put_zero(skb, sizeof(struct can_frame));
+
+	return skb;
+}
+EXPORT_SYMBOL_GPL(alloc_can_skb);
+
+struct sk_buff *alloc_canfd_skb(struct net_device *dev,
+				struct canfd_frame **cfd)
+{
+	struct sk_buff *skb;
+
+	skb = netdev_alloc_skb(dev, sizeof(struct can_skb_priv) +
+			       sizeof(struct canfd_frame));
+	if (unlikely(!skb))
+		return NULL;
+
+	skb->protocol = htons(ETH_P_CANFD);
+	skb->pkt_type = PACKET_BROADCAST;
+	skb->ip_summed = CHECKSUM_UNNECESSARY;
+
+	skb_reset_mac_header(skb);
+	skb_reset_network_header(skb);
+	skb_reset_transport_header(skb);
+
+	can_skb_reserve(skb);
+	can_skb_prv(skb)->ifindex = dev->ifindex;
+	can_skb_prv(skb)->skbcnt = 0;
+
+	*cfd = skb_put_zero(skb, sizeof(struct canfd_frame));
+
+	return skb;
+}
+EXPORT_SYMBOL_GPL(alloc_canfd_skb);
+
+struct sk_buff *alloc_can_err_skb(struct net_device *dev, struct can_frame **cf)
+{
+	struct sk_buff *skb;
+
+	skb = alloc_can_skb(dev, cf);
+	if (unlikely(!skb))
+		return NULL;
+
+	(*cf)->can_id = CAN_ERR_FLAG;
+	(*cf)->len = CAN_ERR_DLC;
+
+	return skb;
+}
+EXPORT_SYMBOL_GPL(alloc_can_err_skb);
diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h
index d75fba1d030a..4a26e128af7f 100644
--- a/include/linux/can/dev.h
+++ b/include/linux/can/dev.h
@@ -84,69 +84,6 @@ struct can_priv {
 #endif
 };
 
-/* Check for outgoing skbs that have not been created by the CAN subsystem */
-static inline bool can_skb_headroom_valid(struct net_device *dev,
-					  struct sk_buff *skb)
-{
-	/* af_packet creates a headroom of HH_DATA_MOD bytes which is fine */
-	if (WARN_ON_ONCE(skb_headroom(skb) < sizeof(struct can_skb_priv)))
-		return false;
-
-	/* af_packet does not apply CAN skb specific settings */
-	if (skb->ip_summed == CHECKSUM_NONE) {
-		/* init headroom */
-		can_skb_prv(skb)->ifindex = dev->ifindex;
-		can_skb_prv(skb)->skbcnt = 0;
-
-		skb->ip_summed = CHECKSUM_UNNECESSARY;
-
-		/* perform proper loopback on capable devices */
-		if (dev->flags & IFF_ECHO)
-			skb->pkt_type = PACKET_LOOPBACK;
-		else
-			skb->pkt_type = PACKET_HOST;
-
-		skb_reset_mac_header(skb);
-		skb_reset_network_header(skb);
-		skb_reset_transport_header(skb);
-	}
-
-	return true;
-}
-
-/* Drop a given socketbuffer if it does not contain a valid CAN frame. */
-static inline bool can_dropped_invalid_skb(struct net_device *dev,
-					  struct sk_buff *skb)
-{
-	const struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
-
-	if (skb->protocol == htons(ETH_P_CAN)) {
-		if (unlikely(skb->len != CAN_MTU ||
-			     cfd->len > CAN_MAX_DLEN))
-			goto inval_skb;
-	} else if (skb->protocol == htons(ETH_P_CANFD)) {
-		if (unlikely(skb->len != CANFD_MTU ||
-			     cfd->len > CANFD_MAX_DLEN))
-			goto inval_skb;
-	} else
-		goto inval_skb;
-
-	if (!can_skb_headroom_valid(dev, skb))
-		goto inval_skb;
-
-	return false;
-
-inval_skb:
-	kfree_skb(skb);
-	dev->stats.tx_dropped++;
-	return true;
-}
-
-static inline bool can_is_canfd_skb(const struct sk_buff *skb)
-{
-	/* the CAN specific type of skb is identified by its data length */
-	return skb->len == CANFD_MTU;
-}
 
 /* helper to define static CAN controller features at device creation time */
 static inline void can_set_static_ctrlmode(struct net_device *dev,
@@ -187,23 +124,10 @@ void can_bus_off(struct net_device *dev);
 void can_change_state(struct net_device *dev, struct can_frame *cf,
 		      enum can_state tx_state, enum can_state rx_state);
 
-int 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);
-
 #ifdef CONFIG_OF
 void of_can_transceiver(struct net_device *dev);
 #else
 static inline void of_can_transceiver(struct net_device *dev) { }
 #endif
 
-struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf);
-struct sk_buff *alloc_canfd_skb(struct net_device *dev,
-				struct canfd_frame **cfd);
-struct sk_buff *alloc_can_err_skb(struct net_device *dev,
-				  struct can_frame **cf);
-
 #endif /* !_CAN_DEV_H */
diff --git a/include/linux/can/skb.h b/include/linux/can/skb.h
index fc61cf4eff1c..c90ebbd3008c 100644
--- a/include/linux/can/skb.h
+++ b/include/linux/can/skb.h
@@ -16,6 +16,19 @@
 #include <linux/can.h>
 #include <net/sock.h>
 
+void can_flush_echo_skb(struct net_device *dev);
+int 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);
+struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf);
+struct sk_buff *alloc_canfd_skb(struct net_device *dev,
+				struct canfd_frame **cfd);
+struct sk_buff *alloc_can_err_skb(struct net_device *dev,
+				  struct can_frame **cf);
+
 /*
  * The struct can_skb_priv is used to transport additional information along
  * with the stored struct can(fd)_frame that can not be contained in existing
@@ -74,4 +87,68 @@ static inline struct sk_buff *can_create_echo_skb(struct sk_buff *skb)
 	return nskb;
 }
 
+/* Check for outgoing skbs that have not been created by the CAN subsystem */
+static inline bool can_skb_headroom_valid(struct net_device *dev,
+					  struct sk_buff *skb)
+{
+	/* af_packet creates a headroom of HH_DATA_MOD bytes which is fine */
+	if (WARN_ON_ONCE(skb_headroom(skb) < sizeof(struct can_skb_priv)))
+		return false;
+
+	/* af_packet does not apply CAN skb specific settings */
+	if (skb->ip_summed == CHECKSUM_NONE) {
+		/* init headroom */
+		can_skb_prv(skb)->ifindex = dev->ifindex;
+		can_skb_prv(skb)->skbcnt = 0;
+
+		skb->ip_summed = CHECKSUM_UNNECESSARY;
+
+		/* perform proper loopback on capable devices */
+		if (dev->flags & IFF_ECHO)
+			skb->pkt_type = PACKET_LOOPBACK;
+		else
+			skb->pkt_type = PACKET_HOST;
+
+		skb_reset_mac_header(skb);
+		skb_reset_network_header(skb);
+		skb_reset_transport_header(skb);
+	}
+
+	return true;
+}
+
+/* Drop a given socketbuffer if it does not contain a valid CAN frame. */
+static inline bool can_dropped_invalid_skb(struct net_device *dev,
+					  struct sk_buff *skb)
+{
+	const struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
+
+	if (skb->protocol == htons(ETH_P_CAN)) {
+		if (unlikely(skb->len != CAN_MTU ||
+			     cfd->len > CAN_MAX_DLEN))
+			goto inval_skb;
+	} else if (skb->protocol == htons(ETH_P_CANFD)) {
+		if (unlikely(skb->len != CANFD_MTU ||
+			     cfd->len > CANFD_MAX_DLEN))
+			goto inval_skb;
+	} else
+		goto inval_skb;
+
+	if (!can_skb_headroom_valid(dev, skb))
+		goto inval_skb;
+
+	return false;
+
+inval_skb:
+	kfree_skb(skb);
+	dev->stats.tx_dropped++;
+	return true;
+}
+
+static inline bool can_is_canfd_skb(const struct sk_buff *skb)
+{
+	/* the CAN specific type of skb is identified by its data length */
+	return skb->len == CANFD_MTU;
+}
+
 #endif /* !_CAN_SKB_H */
-- 
2.29.2