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authorOliver Hartkopp <socketcan@hartkopp.net>2013-01-17 18:43:39 +0100
committerMarc Kleine-Budde <mkl@pengutronix.de>2013-01-26 16:59:01 +0100
commit156c2bb9f88065c8da78814f98fde665a5cbb527 (patch)
treeecd77a89c19ed0e1d420568f85769d7289ac3a37 /drivers/net/can/dev.c
parente2d5f2c7d66224c1a401ed1f797e467c02c025b8 (diff)
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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>
Diffstat (limited to 'drivers/net/can/dev.c')
-rw-r--r--drivers/net/can/dev.c8
1 files changed, 7 insertions, 1 deletions
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 <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));
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