can: canxl: update CAN infrastructure for CAN XL frames

- add new ETH_P_CANXL ethernet protocol type
- update skb checks for CAN XL
- add alloc_canxl_skb() which now needs a data length parameter
- introduce init_can_skb_reserve() to reduce code duplication

Acked-by: Vincent Mailhol <[e-mail]>
Signed-off-by: Oliver Hartkopp <[e-mail]>
Link: https://lore.kernel.org/all/[e-mail]
Signed-off-by: Marc Kleine-Budde <[e-mail]>

drivers/net/can/dev/skb.c

···
 }
 EXPORT_SYMBOL_GPL(can_free_echo_skb);
 
+/* fill common values for CAN sk_buffs */
+static void init_can_skb_reserve(struct sk_buff *skb)
+{
+	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)->skbcnt = 0;
+}
+
 struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf)
 {
 	struct sk_buff *skb;
···
 	}
 
 	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);
+	init_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));
 
···
 	}
 
 	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);
+	init_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_canxl_skb(struct net_device *dev,
+				struct canxl_frame **cxl,
+				unsigned int data_len)
+{
+	struct sk_buff *skb;
+
+	if (data_len < CANXL_MIN_DLEN || data_len > CANXL_MAX_DLEN)
+		goto out_error;
+
+	skb = netdev_alloc_skb(dev, sizeof(struct can_skb_priv) +
+			       CANXL_HDR_SIZE + data_len);
+	if (unlikely(!skb))
+		goto out_error;
+
+	skb->protocol = htons(ETH_P_CANXL);
+	init_can_skb_reserve(skb);
+	can_skb_prv(skb)->ifindex = dev->ifindex;
+
+	*cxl = skb_put_zero(skb, CANXL_HDR_SIZE + data_len);
+
+	/* set CAN XL flag and length information by default */
+	(*cxl)->flags = CANXL_XLF;
+	(*cxl)->len = data_len;
+
+	return skb;
+
+out_error:
+	*cxl = NULL;
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(alloc_canxl_skb);
 
 struct sk_buff *alloc_can_err_skb(struct net_device *dev, struct can_frame **cf)
 {
···
 
 	case ETH_P_CANFD:
 		if (!can_is_canfd_skb(skb))
+			goto inval_skb;
+		break;
+
+	case ETH_P_CANXL:
+		if (!can_is_canxl_skb(skb))
 			goto inval_skb;
 		break;
 

include/linux/can/skb.h

···
 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_canxl_skb(struct net_device *dev,
+				struct canxl_frame **cxl,
+				unsigned int data_len);
 struct sk_buff *alloc_can_err_skb(struct net_device *dev,
 				  struct can_frame **cf);
 bool can_dropped_invalid_skb(struct net_device *dev, struct sk_buff *skb);
···
 	return (skb->len == CANFD_MTU && cfd->len <= CANFD_MAX_DLEN);
 }
 
-/* get length element value from can[fd]_frame structure */
+static inline bool can_is_canxl_skb(const struct sk_buff *skb)
+{
+	const struct canxl_frame *cxl = (struct canxl_frame *)skb->data;
+
+	if (skb->len < CANXL_HDR_SIZE + CANXL_MIN_DLEN || skb->len > CANXL_MTU)
+		return false;
+
+	/* this also checks valid CAN XL data length boundaries */
+	if (skb->len != CANXL_HDR_SIZE + cxl->len)
+		return false;
+
+	return cxl->flags & CANXL_XLF;
+}
+
+/* get length element value from can[|fd|xl]_frame structure */
 static inline unsigned int can_skb_get_len_val(struct sk_buff *skb)
 {
+	const struct canxl_frame *cxl = (struct canxl_frame *)skb->data;
 	const struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
+
+	if (can_is_canxl_skb(skb))
+		return cxl->len;
 
 	return cfd->len;
 }

include/uapi/linux/if_ether.h

···
 #define ETH_P_LOCALTALK 0x0009		/* Localtalk pseudo type 	*/
 #define ETH_P_CAN	0x000C		/* CAN: Controller Area Network */
 #define ETH_P_CANFD	0x000D		/* CANFD: CAN flexible data rate*/
+#define ETH_P_CANXL	0x000E		/* CANXL: eXtended frame Length */
 #define ETH_P_PPPTALK	0x0010		/* Dummy type for Atalk over PPP*/
 #define ETH_P_TR_802_2	0x0011		/* 802.2 frames 		*/
 #define ETH_P_MOBITEX	0x0015		/* Mobitex ([e-mail])	*/

net/can/af_can.c

···
 	struct can_pkg_stats *pkg_stats = dev_net(skb->dev)->can.pkg_stats;
 	int err = -EINVAL;
 
-	if (can_is_can_skb(skb)) {
+	if (can_is_canxl_skb(skb)) {
+		skb->protocol = htons(ETH_P_CANXL);
+	} else if (can_is_can_skb(skb)) {
 		skb->protocol = htons(ETH_P_CAN);
 	} else if (can_is_canfd_skb(skb)) {
 		struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
···
 	return NET_RX_SUCCESS;
 }
 
+static int canxl_rcv(struct sk_buff *skb, struct net_device *dev,
+		     struct packet_type *pt, struct net_device *orig_dev)
+{
+	if (unlikely(dev->type != ARPHRD_CAN || (!can_is_canxl_skb(skb)))) {
+		pr_warn_once("PF_CAN: dropped non conform CAN XL skbuff: dev type %d, len %d\n",
+			     dev->type, skb->len);
+
+		kfree_skb(skb);
+		return NET_RX_DROP;
+	}
+
+	can_receive(skb, dev);
+	return NET_RX_SUCCESS;
+}
+
 /* af_can protocol functions */
 
 /**
···
 	.func = canfd_rcv,
 };
 
+static struct packet_type canxl_packet __read_mostly = {
+	.type = cpu_to_be16(ETH_P_CANXL),
+	.func = canxl_rcv,
+};
+
 static const struct net_proto_family can_family_ops = {
 	.family = PF_CAN,
 	.create = can_create,
···
 
 	dev_add_pack(&can_packet);
 	dev_add_pack(&canfd_packet);
+	dev_add_pack(&canxl_packet);
 
 	return 0;