Commit 156c2bb9 authored by Oliver Hartkopp's avatar Oliver Hartkopp Committed by Marc Kleine-Budde
Browse files

can: add private data space for CAN sk_buffs 



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
struct sk_buff elements.

can_skb_priv is located in the skb headroom, which does not touch the existing
CAN sk_buff usage with skb->data and skb->len, so that even out-of-tree
CAN drivers can be used without changes.

Btw. out-of-tree CAN drivers without can_skb_priv in the sk_buff headroom
would not support features based on can_skb_priv.

The can_skb_priv->ifindex contains the first interface where the CAN frame
appeared on the local host. Unfortunately skb->skb_iif can not be used as this
value is overwritten in every netif_receive_skb() call.

Signed-off-by: default avatarOliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
parent e2d5f2c7

drivers/net/can/dev.c

+7 −1
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ 
#include <linux/if_arp.h>

#include <linux/can.h>

#include <linux/can/dev.h>

#include <linux/can/skb.h>

#include <linux/can/netlink.h>

#include <linux/can/led.h>

#include <net/rtnetlink.h>
@@ -502,13 +503,18 @@ 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_frame));

	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_reserve(skb, sizeof(struct can_skb_priv));

	((struct can_skb_priv *)(skb->head))->ifindex = dev->ifindex;



	*cf = (struct can_frame *)skb_put(skb, sizeof(struct can_frame));

	memset(*cf, 0, sizeof(struct can_frame));

drivers/net/can/slcan.c

+7 −1
Original line number Diff line number Diff line
@@ -55,6 +55,7 @@ 
#include <linux/init.h>

#include <linux/kernel.h>

#include <linux/can.h>

#include <linux/can/skb.h>



static __initconst const char banner[] =

	KERN_INFO "slcan: serial line CAN interface driver\n";
@@ -184,7 +185,8 @@ static void slc_bump(struct slcan *sl) 
		cf.data[i] |= tmp;

	}



	skb = dev_alloc_skb(sizeof(struct can_frame));

	skb = dev_alloc_skb(sizeof(struct can_frame) +

			    sizeof(struct can_skb_priv));

	if (!skb)

		return;
@@ -192,6 +194,10 @@ static void slc_bump(struct slcan *sl) 
	skb->protocol = htons(ETH_P_CAN);

	skb->pkt_type = PACKET_BROADCAST;

	skb->ip_summed = CHECKSUM_UNNECESSARY;



	skb_reserve(skb, sizeof(struct can_skb_priv));

	((struct can_skb_priv *)(skb->head))->ifindex = sl->dev->ifindex;



	memcpy(skb_put(skb, sizeof(struct can_frame)),

	       &cf, sizeof(struct can_frame));

	netif_rx_ni(skb);

include/linux/can/skb.h

0 → 100644
+35 −0
Original line number Diff line number Diff line 
/*

 * linux/can/skb.h

 *

 * Definitions for the CAN network socket buffer

 *

 * Copyright (C) 2012 Oliver Hartkopp <socketcan@hartkopp.net>

 *

 */



#ifndef CAN_SKB_H

#define CAN_SKB_H



#include <linux/types.h>

#include <linux/can.h>



/*

 * 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

 * struct sk_buff elements.

 * N.B. that this information must not be modified in cloned CAN sk_buffs.

 * To modify the CAN frame content or the struct can_skb_priv content

 * skb_copy() needs to be used instead of skb_clone().

 */



/**

 * struct can_skb_priv - private additional data inside CAN sk_buffs

 * @ifindex:	ifindex of the first interface the CAN frame appeared on

 * @cf:		align to the following CAN frame at skb->data

 */

struct can_skb_priv {

	int ifindex;

	struct can_frame cf[0];

};



#endif /* CAN_SKB_H */

net/can/bcm.c

+9 −3
Original line number Diff line number Diff line
@@ -54,6 +54,7 @@ 
#include <linux/skbuff.h>

#include <linux/can.h>

#include <linux/can/core.h>

#include <linux/can/skb.h>

#include <linux/can/bcm.h>

#include <linux/slab.h>

#include <net/sock.h>
@@ -256,10 +257,13 @@ static void bcm_can_tx(struct bcm_op *op) 
		return;

	}



	skb = alloc_skb(CFSIZ, gfp_any());

	skb = alloc_skb(CFSIZ + sizeof(struct can_skb_priv), gfp_any());

	if (!skb)

		goto out;



	skb_reserve(skb, sizeof(struct can_skb_priv));

	((struct can_skb_priv *)(skb->head))->ifindex = dev->ifindex;



	memcpy(skb_put(skb, CFSIZ), cf, CFSIZ);



	/* send with loopback */
@@ -1199,11 +1203,12 @@ static int bcm_tx_send(struct msghdr *msg, int ifindex, struct sock *sk) 
	if (!ifindex)

		return -ENODEV;



	skb = alloc_skb(CFSIZ, GFP_KERNEL);



	skb = alloc_skb(CFSIZ + sizeof(struct can_skb_priv), GFP_KERNEL);

	if (!skb)

		return -ENOMEM;



	skb_reserve(skb, sizeof(struct can_skb_priv));



	err = memcpy_fromiovec(skb_put(skb, CFSIZ), msg->msg_iov, CFSIZ);

	if (err < 0) {

		kfree_skb(skb);
@@ -1216,6 +1221,7 @@ static int bcm_tx_send(struct msghdr *msg, int ifindex, struct sock *sk) 
		return -ENODEV;

	}



	((struct can_skb_priv *)(skb->head))->ifindex = dev->ifindex;

	skb->dev = dev;

	skb->sk  = sk;

	err = can_send(skb, 1); /* send with loopback */

net/can/raw.c

+6 −2
Original line number Diff line number Diff line
@@ -50,6 +50,7 @@ 
#include <linux/skbuff.h>

#include <linux/can.h>

#include <linux/can/core.h>

#include <linux/can/skb.h>

#include <linux/can/raw.h>

#include <net/sock.h>

#include <net/net_namespace.h>
@@ -699,11 +700,14 @@ static int raw_sendmsg(struct kiocb *iocb, struct socket *sock, 
	if (!dev)

		return -ENXIO;



	skb = sock_alloc_send_skb(sk, size, msg->msg_flags & MSG_DONTWAIT,

				  &err);

	skb = sock_alloc_send_skb(sk, size + sizeof(struct can_skb_priv),

				  msg->msg_flags & MSG_DONTWAIT, &err);

	if (!skb)

		goto put_dev;



	skb_reserve(skb, sizeof(struct can_skb_priv));

	((struct can_skb_priv *)(skb->head))->ifindex = dev->ifindex;



	err = memcpy_fromiovec(skb_put(skb, size), msg->msg_iov, size);

	if (err < 0)

		goto free_skb;

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