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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: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Oliver Hartkopp 2013-01-17 18:43:39 +01:00 committed by Marc Kleine-Budde
parent e2d5f2c7d6
commit 156c2bb9f8
5 changed files with 64 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
drivers/net/can/dev.c
View File

@ -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));

8
drivers/net/can/slcan.c
View File

@ -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);

35
include/linux/can/skb.h Normal file
View File

@ -0,0 +1,35 @@
/*
* 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 */

12
net/can/bcm.c
View File

@ -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 */

8
net/can/raw.c
View File

@ -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;