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 <[email protected]>
Signed-off-by: Marc Kleine-Budde <[email protected]>
This commit is contained in:
Oliver Hartkopp 2013-01-17 18:43:39 +01:00 • committed by Marc Kleine-Budde
commit 156c2bb9f8
5 changed files with 64 additions and 7 deletions

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 */

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;