From 156c2bb9f88065c8da78814f98fde665a5cbb527 Mon Sep 17 00:00:00 2001 From: Oliver Hartkopp Date: Thu, 17 Jan 2013 18:43:39 +0100 Subject: [PATCH] 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 Signed-off-by: Marc Kleine-Budde --- drivers/net/can/dev.c | 8 +++++++- drivers/net/can/slcan.c | 8 +++++++- include/linux/can/skb.h | 35 +++++++++++++++++++++++++++++++++++ net/can/bcm.c | 12 +++++++++--- net/can/raw.c | 8 ++++++-- 5 files changed, 64 insertions(+), 7 deletions(-) create mode 100644 include/linux/can/skb.h diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c index 6abc6e5..59ada08 100644 --- a/drivers/net/can/dev.c +++ b/drivers/net/can/dev.c @@ -24,6 +24,7 @@ #include #include #include +#include #include #include #include @@ -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)); diff --git a/drivers/net/can/slcan.c b/drivers/net/can/slcan.c index adc3708..e79a8d1 100644 --- a/drivers/net/can/slcan.c +++ b/drivers/net/can/slcan.c @@ -55,6 +55,7 @@ #include #include #include +#include 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); diff --git a/include/linux/can/skb.h b/include/linux/can/skb.h new file mode 100644 index 0000000..4b0f24d --- /dev/null +++ b/include/linux/can/skb.h @@ -0,0 +1,35 @@ +/* + * linux/can/skb.h + * + * Definitions for the CAN network socket buffer + * + * Copyright (C) 2012 Oliver Hartkopp + * + */ + +#ifndef CAN_SKB_H +#define CAN_SKB_H + +#include +#include + +/* + * 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 */ diff --git a/net/can/bcm.c b/net/can/bcm.c index 969b7cd..ccc27b9 100644 --- a/net/can/bcm.c +++ b/net/can/bcm.c @@ -54,6 +54,7 @@ #include #include #include +#include #include #include #include @@ -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 */ diff --git a/net/can/raw.c b/net/can/raw.c index 5b0e3e3..5d860e8 100644 --- a/net/can/raw.c +++ b/net/can/raw.c @@ -50,6 +50,7 @@ #include #include #include +#include #include #include #include @@ -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; -- 2.7.4