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:
parent
e2d5f2c7d6
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156c2bb9f8
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@ -24,6 +24,7 @@
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#include <linux/if_arp.h>
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#include <linux/can.h>
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#include <linux/can/dev.h>
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#include <linux/can/skb.h>
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#include <linux/can/netlink.h>
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#include <linux/can/led.h>
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#include <net/rtnetlink.h>
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@ -502,13 +503,18 @@ struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf)
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{
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struct sk_buff *skb;
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skb = netdev_alloc_skb(dev, sizeof(struct can_frame));
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skb = netdev_alloc_skb(dev, sizeof(struct can_skb_priv) +
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sizeof(struct can_frame));
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if (unlikely(!skb))
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return NULL;
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skb->protocol = htons(ETH_P_CAN);
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skb->pkt_type = PACKET_BROADCAST;
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skb->ip_summed = CHECKSUM_UNNECESSARY;
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skb_reserve(skb, sizeof(struct can_skb_priv));
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((struct can_skb_priv *)(skb->head))->ifindex = dev->ifindex;
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*cf = (struct can_frame *)skb_put(skb, sizeof(struct can_frame));
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memset(*cf, 0, sizeof(struct can_frame));
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@ -55,6 +55,7 @@
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/can.h>
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#include <linux/can/skb.h>
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static __initconst const char banner[] =
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KERN_INFO "slcan: serial line CAN interface driver\n";
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@ -184,7 +185,8 @@ static void slc_bump(struct slcan *sl)
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cf.data[i] |= tmp;
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}
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skb = dev_alloc_skb(sizeof(struct can_frame));
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skb = dev_alloc_skb(sizeof(struct can_frame) +
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sizeof(struct can_skb_priv));
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if (!skb)
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return;
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@ -192,6 +194,10 @@ static void slc_bump(struct slcan *sl)
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skb->protocol = htons(ETH_P_CAN);
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skb->pkt_type = PACKET_BROADCAST;
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skb->ip_summed = CHECKSUM_UNNECESSARY;
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skb_reserve(skb, sizeof(struct can_skb_priv));
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((struct can_skb_priv *)(skb->head))->ifindex = sl->dev->ifindex;
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memcpy(skb_put(skb, sizeof(struct can_frame)),
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&cf, sizeof(struct can_frame));
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netif_rx_ni(skb);
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35
include/linux/can/skb.h
Normal file
35
include/linux/can/skb.h
Normal file
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@ -0,0 +1,35 @@
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/*
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* linux/can/skb.h
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*
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* Definitions for the CAN network socket buffer
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*
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* Copyright (C) 2012 Oliver Hartkopp <socketcan@hartkopp.net>
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*
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*/
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#ifndef CAN_SKB_H
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#define CAN_SKB_H
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#include <linux/types.h>
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#include <linux/can.h>
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/*
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* The struct can_skb_priv is used to transport additional information along
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* with the stored struct can(fd)_frame that can not be contained in existing
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* struct sk_buff elements.
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* N.B. that this information must not be modified in cloned CAN sk_buffs.
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* To modify the CAN frame content or the struct can_skb_priv content
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* skb_copy() needs to be used instead of skb_clone().
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*/
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/**
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* struct can_skb_priv - private additional data inside CAN sk_buffs
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* @ifindex: ifindex of the first interface the CAN frame appeared on
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* @cf: align to the following CAN frame at skb->data
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*/
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struct can_skb_priv {
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int ifindex;
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struct can_frame cf[0];
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};
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#endif /* CAN_SKB_H */
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@ -54,6 +54,7 @@
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#include <linux/skbuff.h>
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#include <linux/can.h>
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#include <linux/can/core.h>
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#include <linux/can/skb.h>
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#include <linux/can/bcm.h>
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#include <linux/slab.h>
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#include <net/sock.h>
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@ -256,10 +257,13 @@ static void bcm_can_tx(struct bcm_op *op)
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return;
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}
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skb = alloc_skb(CFSIZ, gfp_any());
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skb = alloc_skb(CFSIZ + sizeof(struct can_skb_priv), gfp_any());
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if (!skb)
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goto out;
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skb_reserve(skb, sizeof(struct can_skb_priv));
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((struct can_skb_priv *)(skb->head))->ifindex = dev->ifindex;
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memcpy(skb_put(skb, CFSIZ), cf, CFSIZ);
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/* send with loopback */
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@ -1199,11 +1203,12 @@ static int bcm_tx_send(struct msghdr *msg, int ifindex, struct sock *sk)
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if (!ifindex)
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return -ENODEV;
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skb = alloc_skb(CFSIZ, GFP_KERNEL);
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skb = alloc_skb(CFSIZ + sizeof(struct can_skb_priv), GFP_KERNEL);
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if (!skb)
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return -ENOMEM;
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skb_reserve(skb, sizeof(struct can_skb_priv));
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err = memcpy_fromiovec(skb_put(skb, CFSIZ), msg->msg_iov, CFSIZ);
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if (err < 0) {
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kfree_skb(skb);
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@ -1216,6 +1221,7 @@ static int bcm_tx_send(struct msghdr *msg, int ifindex, struct sock *sk)
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return -ENODEV;
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}
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((struct can_skb_priv *)(skb->head))->ifindex = dev->ifindex;
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skb->dev = dev;
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skb->sk = sk;
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err = can_send(skb, 1); /* send with loopback */
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@ -50,6 +50,7 @@
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#include <linux/skbuff.h>
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#include <linux/can.h>
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#include <linux/can/core.h>
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#include <linux/can/skb.h>
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#include <linux/can/raw.h>
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#include <net/sock.h>
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#include <net/net_namespace.h>
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@ -699,11 +700,14 @@ static int raw_sendmsg(struct kiocb *iocb, struct socket *sock,
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if (!dev)
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return -ENXIO;
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skb = sock_alloc_send_skb(sk, size, msg->msg_flags & MSG_DONTWAIT,
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&err);
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skb = sock_alloc_send_skb(sk, size + sizeof(struct can_skb_priv),
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msg->msg_flags & MSG_DONTWAIT, &err);
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if (!skb)
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goto put_dev;
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skb_reserve(skb, sizeof(struct can_skb_priv));
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((struct can_skb_priv *)(skb->head))->ifindex = dev->ifindex;
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err = memcpy_fromiovec(skb_put(skb, size), msg->msg_iov, size);
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if (err < 0)
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goto free_skb;
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