[PATCH 2/2] ipv4: Change rt->rt_iif encoding.

[PATCH 2/2] ipv4: Change rt->rt_iif encoding.

[David Miller]

On input packet processing, rt->rt_iif will be zero if we should
use skb->dev->ifindex.

Since we access rt->rt_iif consistently via inet_iif(), that is
the only spot whose interpretation have to adjust.

Signed-off-by: David S. Miller <davem@davemloft.net>
---
 include/net/route.h |    6 +++++-
 net/ipv4/route.c    |    8 ++++----
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/include/net/route.h b/include/net/route.h
index 60d611d..d418ae1 100644
--- a/include/net/route.h
+++ b/include/net/route.h
@@ -277,7 +277,11 @@ static inline struct rtable *ip_route_newports(struct flowi4 *fl4, struct rtable
 
 static inline int inet_iif(const struct sk_buff *skb)
 {
-	return skb_rtable(skb)->rt_iif;
+	int iif = skb_rtable(skb)->rt_iif;
+
+	if (iif)
+		return iif;
+	return skb->dev->ifindex;
 }
 
 extern int sysctl_ip_default_ttl;
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index f6be781..6bcb8fc 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1309,7 +1309,7 @@ static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
 	rth->rt_flags	= RTCF_MULTICAST;
 	rth->rt_type	= RTN_MULTICAST;
 	rth->rt_is_input= 1;
-	rth->rt_iif	= dev->ifindex;
+	rth->rt_iif	= 0;
 	rth->rt_pmtu	= 0;
 	rth->rt_gateway	= 0;
 	if (our) {
@@ -1435,7 +1435,7 @@ static int __mkroute_input(struct sk_buff *skb,
 	rth->rt_flags = flags;
 	rth->rt_type = res->type;
 	rth->rt_is_input = 1;
-	rth->rt_iif 	= in_dev->dev->ifindex;
+	rth->rt_iif 	= 0;
 	rth->rt_pmtu	= 0;
 	rth->rt_gateway	= 0;
 
@@ -1608,7 +1608,7 @@ local_input:
 	rth->rt_flags 	= flags|RTCF_LOCAL;
 	rth->rt_type	= res.type;
 	rth->rt_is_input = 1;
-	rth->rt_iif	= dev->ifindex;
+	rth->rt_iif	= 0;
 	rth->rt_pmtu	= 0;
 	rth->rt_gateway	= 0;
 	if (res.type == RTN_UNREACHABLE) {
@@ -1772,7 +1772,7 @@ static struct rtable *__mkroute_output(const struct fib_result *res,
 	rth->rt_flags	= flags;
 	rth->rt_type	= type;
 	rth->rt_is_input = 0;
-	rth->rt_iif	= orig_oif ? : dev_out->ifindex;
+	rth->rt_iif	= orig_oif ? : 0;
 	rth->rt_pmtu	= 0;
 	rth->rt_gateway = 0;
 
-- 
1.7.10.4

Re: [PATCH 2/2] ipv4: Change rt->rt_iif encoding.

[David Miller]

From: David Miller <davem@davemloft.net>
Date: Mon, 23 Jul 2012 14:07:37 -0700 (PDT)

> On input packet processing, rt->rt_iif will be zero if we should
> use skb->dev->ifindex.
> 
> Since we access rt->rt_iif consistently via inet_iif(), that is
> the only spot whose interpretation have to adjust.
> 
> Signed-off-by: David S. Miller <davem@davemloft.net>

Julian, as you seem to have feared, this turns out to not work.

We zap the skb->dev apparently, so I'll need to come up with
a different scheme to handle this.

Re: [PATCH 2/2] ipv4: Change rt->rt_iif encoding.

[David Miller]

From: David Miller <davem@davemloft.net>
Date: Mon, 23 Jul 2012 15:22:20 -0700 (PDT)

> From: David Miller <davem@davemloft.net>
> Date: Mon, 23 Jul 2012 14:07:37 -0700 (PDT)
> 
>> On input packet processing, rt->rt_iif will be zero if we should
>> use skb->dev->ifindex.
>> 
>> Since we access rt->rt_iif consistently via inet_iif(), that is
>> the only spot whose interpretation have to adjust.
>> 
>> Signed-off-by: David S. Miller <davem@davemloft.net>
> 
> Julian, as you seem to have feared, this turns out to not work.
> 
> We zap the skb->dev apparently, so I'll need to come up with
> a different scheme to handle this.

Just to clarify, the specific issue is that tcp input will set
skb->dev to NULL right before we lock the socket and try to process
the packet in that socket's context.

So inet_iif() implemented conditionally using skb->dev won't
work without some kind of adjustment.

And we need to do inet_iif() even after we have the top-level
socket in-hand, in order to lookup listener socket children,
and maintain the cached RX dst.

Oddly enough, I had expected that this sort of change came from Eric
Dumazet as some kind of optimization, but it's rather a poorly
documented change from many years ago apparently written by your's
truly :-)

--------------------
commit 72ffc30d67f33b69ce4596b940a66e45bf5994b3
Author: davem <davem>
Date:   Fri Dec 8 17:15:53 2000 +0000

    Kill both is_clone and rx_dev from sk_buff, both
    were superfluous.

diff --git a/drivers/net/pppoe.c b/drivers/net/pppoe.c
index feb7236..8744f61 100644
--- a/drivers/net/pppoe.c
+++ b/drivers/net/pppoe.c
@@ -785,8 +785,7 @@ int pppoe_sendmsg(struct socket *sock, struct msghdr *m,
 	skb_reserve(skb, dev->hard_header_len);
 	skb->nh.raw = skb->data;
 
-	skb->rx_dev = skb->dev = dev;
-	dev_hold(skb->rx_dev);
+	skb->dev = dev;
 
 	skb->priority = sk->priority;
 	skb->protocol = __constant_htons(ETH_P_PPP_SES);
@@ -869,11 +868,7 @@ int __pppoe_xmit(struct sock *sk, struct sk_buff *skb)
 
 	skb->nh.raw = skb->data;
 
-	/* Change device of skb, update reference counts */
-	if(skb->rx_dev)
-	    dev_put(skb->rx_dev);
-	skb->rx_dev = skb->dev = dev;
-	dev_hold(skb->rx_dev);
+	skb->dev = dev;
 
 	dev->hard_header(skb, dev, ETH_P_PPP_SES,
 			 sk->protinfo.pppox->pppoe_pa.remote,
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index c67f8c8..17e48d0 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -65,8 +65,7 @@ struct sk_buff {
 	struct sk_buff_head * list;		/* List we are on				*/
 	struct sock	*sk;			/* Socket we are owned by 			*/
 	struct timeval	stamp;			/* Time we arrived				*/
-	struct net_device	*dev;			/* Device we arrived on/are leaving by		*/
-	struct net_device	*rx_dev;
+	struct net_device	*dev;		/* Device we arrived on/are leaving by		*/
 
 	/* Transport layer header */
 	union
@@ -110,8 +109,7 @@ struct sk_buff {
 	unsigned int 	len;			/* Length of actual data			*/
 	unsigned int	csum;			/* Checksum 					*/
 	volatile char 	used;			/* Data moved to user and not MSG_PEEK		*/
-	unsigned char	is_clone,		/* We are a clone				*/
-			cloned, 		/* head may be cloned (check refcnt to be sure). */
+	unsigned char	cloned, 		/* head may be cloned (check refcnt to be sure). */
   			pkt_type,		/* Packet class					*/
   			ip_summed;		/* Driver fed us an IP checksum			*/
 	__u32		priority;		/* Packet queueing priority			*/
diff --git a/include/net/sock.h b/include/net/sock.h
index 4b3a82b..8550282 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1169,6 +1169,7 @@ static inline int sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 	}
 #endif /* CONFIG_FILTER */
 
+	skb->dev = NULL;
 	skb_set_owner_r(skb, sk);
 	skb_queue_tail(&sk->receive_queue, skb);
 	if (!sk->dead)
diff --git a/net/core/dev.c b/net/core/dev.c
index 0f097b8..f8d5437 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -617,7 +617,7 @@ void netdev_state_change(struct net_device *dev)
 
 void dev_load(const char *name)
 {
-	if (!__dev_get_by_name(name) && capable(CAP_SYS_MODULE))
+	if (!dev_get(name) && capable(CAP_SYS_MODULE))
 		request_module(name);
 }
 
@@ -875,8 +875,6 @@ void dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev)
 
 			skb2->h.raw = skb2->nh.raw;
 			skb2->pkt_type = PACKET_OUTGOING;
-			skb2->rx_dev = skb->dev;
-			dev_hold(skb2->rx_dev);
 			ptype->func(skb2, skb->dev, ptype);
 		}
 	}
@@ -1129,10 +1127,7 @@ int netif_rx(struct sk_buff *skb)
 				goto drop;
 
 enqueue:
-			if (skb->rx_dev)
-				dev_put(skb->rx_dev);
-			skb->rx_dev = skb->dev;
-			dev_hold(skb->rx_dev);
+			dev_hold(skb->dev);
 			__skb_queue_tail(&queue->input_pkt_queue,skb);
 			__cpu_raise_softirq(this_cpu, NET_RX_SOFTIRQ);
 			local_irq_restore(flags);
@@ -1206,11 +1201,11 @@ static int deliver_to_old_ones(struct packet_type *pt, struct sk_buff *skb, int
  */
 static __inline__ void skb_bond(struct sk_buff *skb)
 {
-	struct net_device *dev = skb->rx_dev;
+	struct net_device *dev = skb->dev;
 	
 	if (dev->master) {
 		dev_hold(dev->master);
-		skb->dev = skb->rx_dev = dev->master;
+		skb->dev = dev->master;
 		dev_put(dev);
 	}
 }
@@ -1320,6 +1315,7 @@ static void net_rx_action(struct softirq_action *h)
 
 	for (;;) {
 		struct sk_buff *skb;
+		struct net_device *rx_dev;
 
 		local_irq_disable();
 		skb = __skb_dequeue(&queue->input_pkt_queue);
@@ -1330,10 +1326,13 @@ static void net_rx_action(struct softirq_action *h)
 
 		skb_bond(skb);
 
+		rx_dev = skb->dev;
+
 #ifdef CONFIG_NET_FASTROUTE
 		if (skb->pkt_type == PACKET_FASTROUTE) {
 			netdev_rx_stat[this_cpu].fastroute_deferred_out++;
 			dev_queue_xmit(skb);
+			dev_put(rx_dev);
 			continue;
 		}
 #endif
@@ -1369,6 +1368,7 @@ static void net_rx_action(struct softirq_action *h)
 			if (skb->dev->br_port != NULL &&
 			    br_handle_frame_hook != NULL) {
 				handle_bridge(skb, pt_prev);
+				dev_put(rx_dev)
 				continue;
 			}
 #endif
@@ -1399,6 +1399,8 @@ static void net_rx_action(struct softirq_action *h)
 				kfree_skb(skb);
 		}
 
+		dev_put(rx_dev);
+
 		if (bugdet-- < 0 || jiffies - start_time > 1)
 			goto softnet_break;
 
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index d7f575d..1d8dc09 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -4,7 +4,7 @@
  *	Authors:	Alan Cox <iiitac@pyr.swan.ac.uk>
  *			Florian La Roche <rzsfl@rz.uni-sb.de>
  *
- *	Version:	$Id: skbuff.c,v 1.74 2000-12-06 11:45:19 anton Exp $
+ *	Version:	$Id: skbuff.c,v 1.75 2000-12-08 17:15:53 davem Exp $
  *
  *	Fixes:	
  *		Alan Cox	:	Fixed the worst of the load balancer bugs.
@@ -202,7 +202,6 @@ struct sk_buff *alloc_skb(unsigned int size,int gfp_mask)
 
 	/* Set up other state */
 	skb->len = 0;
-	skb->is_clone = 0;
 	skb->cloned = 0;
 
 	atomic_set(&skb->users, 1); 
@@ -233,7 +232,6 @@ static inline void skb_headerinit(void *p, kmem_cache_t *cache,
 	skb->ip_summed = 0;
 	skb->security = 0;	/* By default packets are insecure */
 	skb->dst = NULL;
-	skb->rx_dev = NULL;
 #ifdef CONFIG_NETFILTER
 	skb->nfmark = skb->nfcache = 0;
 	skb->nfct = NULL;
@@ -287,10 +285,6 @@ void __kfree_skb(struct sk_buff *skb)
 #ifdef CONFIG_NETFILTER
 	nf_conntrack_put(skb->nfct);
 #endif
-#ifdef CONFIG_NET		
-	if(skb->rx_dev)
-		dev_put(skb->rx_dev);
-#endif		
 	skb_headerinit(skb, NULL, 0);  /* clean state */
 	kfree_skbmem(skb);
 }
@@ -325,12 +319,10 @@ struct sk_buff *skb_clone(struct sk_buff *skb, int gfp_mask)
 	skb->cloned = 1;
        
 	dst_clone(n->dst);
-	n->rx_dev = NULL;
 	n->cloned = 1;
 	n->next = n->prev = NULL;
 	n->list = NULL;
 	n->sk = NULL;
-	n->is_clone = 1;
 	atomic_set(&n->users, 1);
 	n->destructor = NULL;
 #ifdef CONFIG_NETFILTER
@@ -349,7 +341,6 @@ static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
 	new->list=NULL;
 	new->sk=NULL;
 	new->dev=old->dev;
-	new->rx_dev=NULL;
 	new->priority=old->priority;
 	new->protocol=old->protocol;
 	new->dst=dst_clone(old->dst);
@@ -358,7 +349,6 @@ static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
 	new->mac.raw=old->mac.raw+offset;
 	memcpy(new->cb, old->cb, sizeof(old->cb));
 	new->used=old->used;
-	new->is_clone=0;
 	atomic_set(&new->users, 1);
 	new->pkt_type=old->pkt_type;
 	new->stamp=old->stamp;
diff --git a/net/decnet/dn_nsp_in.c b/net/decnet/dn_nsp_in.c
index 4754cd8..3617294 100644
--- a/net/decnet/dn_nsp_in.c
+++ b/net/decnet/dn_nsp_in.c
@@ -78,9 +78,9 @@ extern int decnet_log_martians;
 static void dn_log_martian(struct sk_buff *skb, const char *msg)
 {
 	if (decnet_log_martians && net_ratelimit()) {
-		char *devname = skb->rx_dev ? skb->rx_dev->name : "???";
+		char *devname = skb->dev ? skb->dev->name : "???";
 		struct dn_skb_cb *cb = (struct dn_skb_cb *)skb->cb;
-		printk(KERN_INFO "DECnet: Martian packet (%s) rx_dev=%s src=0x%04hx dst=0x%04hx srcport=0x%04hx dstport=0x%04hx\n", msg, devname, cb->src, cb->dst, cb->src_port, cb->dst_port);
+		printk(KERN_INFO "DECnet: Martian packet (%s) dev=%s src=0x%04hx dst=0x%04hx srcport=0x%04hx dstport=0x%04hx\n", msg, devname, cb->src, cb->dst, cb->src_port, cb->dst_port);
 	}
 }
 
@@ -782,7 +782,7 @@ free_out:
 
 int dn_nsp_rx(struct sk_buff *skb)
 {
-	return NF_HOOK(PF_DECnet, NF_DN_LOCAL_IN, skb, skb->rx_dev, NULL, dn_nsp_rx_packet);
+	return NF_HOOK(PF_DECnet, NF_DN_LOCAL_IN, skb, skb->dev, NULL, dn_nsp_rx_packet);
 }
 
 /*
diff --git a/net/decnet/dn_route.c b/net/decnet/dn_route.c
index 20ec07a..70646fc 100644
--- a/net/decnet/dn_route.c
+++ b/net/decnet/dn_route.c
@@ -526,6 +526,7 @@ static int dn_forward(struct sk_buff *skb)
 {
 	struct dn_skb_cb *cb = (struct dn_skb_cb *)skb->cb;
 	struct dst_entry *dst = skb->dst;
+	struct net_device *dev = skb->dev;
 	struct neighbour *neigh;
 	int err = -EINVAL;
 
@@ -551,7 +552,7 @@ static int dn_forward(struct sk_buff *skb)
 	else
 		cb->rt_flags &= ~DN_RT_F_IE;
 
-	return NF_HOOK(PF_DECnet, NF_DN_FORWARD, skb, skb->rx_dev, skb->dev, neigh->output);
+	return NF_HOOK(PF_DECnet, NF_DN_FORWARD, skb, dev, skb->dev, neigh->output);
 
 
 error:
@@ -985,7 +986,6 @@ int dn_cache_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh, void *arg)
 		}
 		skb->protocol = __constant_htons(ETH_P_DNA_RT);
 		skb->dev = dev;
-		skb->rx_dev = dev;
 		cb->src = src;
 		cb->dst = dst;
 		local_bh_disable();
@@ -1002,7 +1002,6 @@ int dn_cache_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh, void *arg)
 	if (skb->dev)
 		dev_put(skb->dev);
 	skb->dev = NULL;
-	skb->rx_dev = NULL;
 	if (err)
 		goto out_free;
 	skb->dst = &rt->u.dst;
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index b520899..3dec2c7 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -5,7 +5,7 @@
  *
  *		The IP fragmentation functionality.
  *		
- * Version:	$Id: ip_fragment.c,v 1.52 2000-11-28 13:32:54 davem Exp $
+ * Version:	$Id: ip_fragment.c,v 1.53 2000-12-08 17:15:53 davem Exp $
  *
  * Authors:	Fred N. van Kempen <waltje@uWalt.NL.Mugnet.ORG>
  *		Alan Cox <Alan.Cox@linux.org>
@@ -83,7 +83,7 @@ struct ipq {
 	atomic_t	refcnt;
 	struct timer_list timer;	/* when will this queue expire?		*/
 	struct ipq	**pprev;
-	struct net_device	*dev;	/* Device - for icmp replies */
+	int		iif;		/* Device index - for icmp replies	*/
 };
 
 /* Hash table. */
@@ -255,8 +255,13 @@ static void ip_expire(unsigned long arg)
 	IP_INC_STATS_BH(IpReasmFails);
 
 	if ((qp->last_in&FIRST_IN) && qp->fragments != NULL) {
+		struct sk_buff *head = qp->fragments;
+
 		/* Send an ICMP "Fragment Reassembly Timeout" message. */
-		icmp_send(qp->fragments, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, 0);
+		if ((head->dev = dev_get_by_index(qp->iif)) != NULL) {
+			icmp_send(head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, 0);
+			dev_put(head->dev);
+		}
 	}
 out:
 	spin_unlock(&qp->lock);
@@ -480,7 +485,8 @@ static void ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
 	else
 		qp->fragments = skb;
 
-	qp->dev = skb->dev;
+	qp->iif = skb->dev->ifindex;
+	skb->dev = NULL;
 	qp->meat += skb->len;
 	atomic_add(skb->truesize, &ip_frag_mem);
 	if (offset == 0)
@@ -499,7 +505,7 @@ err:
  * of bits on input. Until the new skb data handling is in I'm not going
  * to touch this with a bargepole. 
  */
-static struct sk_buff *ip_frag_reasm(struct ipq *qp)
+static struct sk_buff *ip_frag_reasm(struct ipq *qp, struct net_device *dev)
 {
 	struct sk_buff *skb;
 	struct iphdr *iph;
@@ -546,7 +552,7 @@ static struct sk_buff *ip_frag_reasm(struct ipq *qp)
 	skb->dst = dst_clone(head->dst);
 	skb->pkt_type = head->pkt_type;
 	skb->protocol = head->protocol;
-	skb->dev = qp->dev;
+	skb->dev = dev;
 
 	/*
 	*  Clearly bogus, because security markings of the individual
@@ -595,6 +601,7 @@ struct sk_buff *ip_defrag(struct sk_buff *skb)
 {
 	struct iphdr *iph = skb->nh.iph;
 	struct ipq *qp;
+	struct net_device *dev;
 	
 	IP_INC_STATS_BH(IpReasmReqds);
 
@@ -602,6 +609,8 @@ struct sk_buff *ip_defrag(struct sk_buff *skb)
 	if (atomic_read(&ip_frag_mem) > sysctl_ipfrag_high_thresh)
 		ip_evictor();
 
+	dev = skb->dev;
+
 	/* Lookup (or create) queue header */
 	if ((qp = ip_find(iph)) != NULL) {
 		struct sk_buff *ret = NULL;
@@ -612,7 +621,7 @@ struct sk_buff *ip_defrag(struct sk_buff *skb)
 
 		if (qp->last_in == (FIRST_IN|LAST_IN) &&
 		    qp->meat == qp->len)
-			ret = ip_frag_reasm(qp);
+			ret = ip_frag_reasm(qp, dev);
 
 		spin_unlock(&qp->lock);
 		ipq_put(qp);
diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index 120c844..c98617d 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -5,7 +5,7 @@
  *
  *		The Internet Protocol (IP) module.
  *
- * Version:	$Id: ip_input.c,v 1.50 2000-10-24 22:54:26 davem Exp $
+ * Version:	$Id: ip_input.c,v 1.51 2000-12-08 17:15:53 davem Exp $
  *
  * Authors:	Ross Biro, <bir7@leland.Stanford.Edu>
  *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
@@ -225,12 +225,6 @@ static inline int ip_local_deliver_finish(struct sk_buff *skb)
 	nf_debug_ip_local_deliver(skb);
 #endif /*CONFIG_NETFILTER_DEBUG*/
 
-	/* Free rx_dev before enqueueing to sockets */
-	if (skb->rx_dev) {
-		dev_put(skb->rx_dev);
-		skb->rx_dev = NULL;
-	}
-
         /* Point into the IP datagram, just past the header. */
         skb->h.raw = skb->nh.raw + iph->ihl*4;
 
diff --git a/net/ipv4/netfilter/ip_queue.c b/net/ipv4/netfilter/ip_queue.c
index 73fd4ea..9c8d493 100644
--- a/net/ipv4/netfilter/ip_queue.c
+++ b/net/ipv4/netfilter/ip_queue.c
@@ -400,13 +400,6 @@ static struct sk_buff *netlink_build_message(ipq_queue_element_t *e, int *errp)
 	if (e->info->outdev) strcpy(pm->outdev_name, e->info->outdev->name);
 	else pm->outdev_name[0] = '\0';
 	pm->hw_protocol = e->skb->protocol;
-	if (e->skb->rx_dev) {
-		pm->hw_type = e->skb->rx_dev->type;
-		if (e->skb->rx_dev->hard_header_parse)
-			pm->hw_addrlen =
-				e->skb->rx_dev->hard_header_parse(e->skb,
-				                                  pm->hw_addr);
-	}
 	if (data_len)
 		memcpy(pm->payload, e->skb->data, data_len);
 	nlh->nlmsg_len = skb->tail - old_tail;
diff --git a/net/ipv4/netfilter/ipt_MIRROR.c b/net/ipv4/netfilter/ipt_MIRROR.c
index cb5362d..9449c51 100644
--- a/net/ipv4/netfilter/ipt_MIRROR.c
+++ b/net/ipv4/netfilter/ipt_MIRROR.c
@@ -50,7 +50,7 @@ static int route_mirror(struct sk_buff *skb)
 
 	/* check if the interface we are leaving by is the same as the
            one we arrived on */
-	if (skb->rx_dev == rt->u.dst.dev) {
+	if (skb->dev == rt->u.dst.dev) {
 		/* Drop old route. */
 		dst_release(skb->dst);
 		skb->dst = &rt->u.dst;
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 27ff7be..7c06a6b 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -5,7 +5,7 @@
  *
  *		Implementation of the Transmission Control Protocol(TCP).
  *
- * Version:	$Id: tcp_ipv4.c,v 1.221 2000-11-28 17:04:10 davem Exp $
+ * Version:	$Id: tcp_ipv4.c,v 1.222 2000-12-08 17:15:53 davem Exp $
  *
  *		IPv4 specific functions
  *
@@ -1649,6 +1649,8 @@ process:
 	if (sk->state == TCP_TIME_WAIT)
 		goto do_time_wait;
 
+	skb->dev = NULL;
+
 	bh_lock_sock(sk);
 	ret = 0;
 	if (!sk->lock.users) {
diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
index c5b645d..41b42a4 100644
--- a/net/ipv6/ip6_input.c
+++ b/net/ipv6/ip6_input.c
@@ -6,7 +6,7 @@
  *	Pedro Roque		<roque@di.fc.ul.pt>
  *	Ian P. Morris		<I.P.Morris@soton.ac.uk>
  *
- *	$Id: ip6_input.c,v 1.17 2000-02-27 19:42:53 davem Exp $
+ *	$Id: ip6_input.c,v 1.18 2000-12-08 17:15:54 davem Exp $
  *
  *	Based in linux/net/ipv4/ip_input.c
  *
@@ -146,11 +146,6 @@ static inline int ip6_input_finish(struct sk_buff *skb)
 	}
 	len = skb->tail - skb->h.raw;
 
-	if (skb->rx_dev) {
-		dev_put(skb->rx_dev);
-		skb->rx_dev = NULL;
-	}
-
 	raw_sk = raw_v6_htable[nexthdr&(MAX_INET_PROTOS-1)];
 	if (raw_sk)
 		raw_sk = ipv6_raw_deliver(skb, nexthdr, len);
diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
index 4111466..edfdc23 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -5,7 +5,7 @@
  *	Authors:
  *	Pedro Roque		<roque@di.fc.ul.pt>	
  *
- *	$Id: reassembly.c,v 1.20 2000-11-28 13:48:03 davem Exp $
+ *	$Id: reassembly.c,v 1.21 2000-12-08 17:15:54 davem Exp $
  *
  *	Based on: net/ipv4/ip_fragment.c
  *
@@ -78,7 +78,6 @@ struct frag_queue
 	struct sk_buff		*fragments;
 	int			len;
 	int			meat;
-	struct net_device	*dev;
 	int			iif;
 	__u8			last_in;	/* has first/last segment arrived? */
 #define COMPLETE		4
@@ -476,8 +475,8 @@ static void ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
 	else
 		fq->fragments = skb;
 
-	fq->dev = skb->dev;
 	fq->iif = skb->dev->ifindex;
+	skb->dev = NULL;
 	fq->meat += skb->len;
 	atomic_add(skb->truesize, &ip6_frag_mem);
 
@@ -507,7 +506,8 @@ err:
  *	queue is eligible for reassembly i.e. it is not COMPLETE,
  *	the last and the first frames arrived and all the bits are here.
  */
-static u8* ip6_frag_reasm(struct frag_queue *fq, struct sk_buff **skb_in)
+static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff **skb_in,
+			  struct net_device *dev)
 {
 	struct sk_buff *fp, *head = fq->fragments;
 	struct sk_buff *skb;
@@ -541,7 +541,7 @@ static u8* ip6_frag_reasm(struct frag_queue *fq, struct sk_buff **skb_in)
 
 	skb->mac.raw = skb->data;
 	skb->nh.ipv6h = (struct ipv6hdr *) skb->data;
-	skb->dev = fq->dev;
+	skb->dev = dev;
 	skb->protocol = __constant_htons(ETH_P_IPV6);
 	skb->pkt_type = head->pkt_type;
 	FRAG6_CB(skb)->h = FRAG6_CB(head)->h;
@@ -579,6 +579,7 @@ u8* ipv6_reassembly(struct sk_buff **skbp, __u8 *nhptr)
 {
 	struct sk_buff *skb = *skbp; 
 	struct frag_hdr *fhdr = (struct frag_hdr *) (skb->h.raw);
+	struct net_device *dev = skb->dev;
 	struct frag_queue *fq;
 	struct ipv6hdr *hdr;
 
@@ -616,7 +617,7 @@ u8* ipv6_reassembly(struct sk_buff **skbp, __u8 *nhptr)
 
 		if (fq->last_in == (FIRST_IN|LAST_IN) &&
 		    fq->meat == fq->len)
-			ret = ip6_frag_reasm(fq, skbp);
+			ret = ip6_frag_reasm(fq, skbp, dev);
 
 		spin_unlock(&fq->lock);
 		fq_put(fq);
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 0801f14..bfb5aef 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -5,7 +5,7 @@
  *	Authors:
  *	Pedro Roque		<roque@di.fc.ul.pt>	
  *
- *	$Id: tcp_ipv6.c,v 1.127 2000-11-28 17:04:10 davem Exp $
+ *	$Id: tcp_ipv6.c,v 1.128 2000-12-08 17:15:54 davem Exp $
  *
  *	Based on: 
  *	linux/net/ipv4/tcp.c
@@ -1576,6 +1576,8 @@ process:
 	if(sk->state == TCP_TIME_WAIT)
 		goto do_time_wait;
 
+	skb->dev = NULL;
+
 	bh_lock_sock(sk);
 	ret = 0;
 	if (!sk->lock.users) {
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index b30efe7..b76a320 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -5,7 +5,7 @@
  *
  *		PACKET - implements raw packet sockets.
  *
- * Version:	$Id: af_packet.c,v 1.46 2000-10-24 21:26:19 davem Exp $
+ * Version:	$Id: af_packet.c,v 1.47 2000-12-08 17:15:54 davem Exp $
  *
  * Authors:	Ross Biro, <bir7@leland.Stanford.Edu>
  *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
@@ -264,11 +264,6 @@ static int packet_rcv_spkt(struct sk_buff *skb, struct net_device *dev,  struct
 	strncpy(spkt->spkt_device, dev->name, sizeof(spkt->spkt_device));
 	spkt->spkt_protocol = skb->protocol;
 
-	if (skb->rx_dev) {
-		dev_put(skb->rx_dev);
-		skb->rx_dev = NULL;
-	}
-
 	/*
 	 *	Charge the memory to the socket. This is done specifically
 	 *	to prevent sockets using all the memory up.
@@ -482,17 +477,13 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev,  struct packe
 	if (dev->hard_header_parse)
 		sll->sll_halen = dev->hard_header_parse(skb, sll->sll_addr);
 
-	if (skb->rx_dev) {
-		dev_put(skb->rx_dev);
-		skb->rx_dev = NULL;
-	}
-
 #ifdef CONFIG_FILTER
 	if (skb->len > snaplen)
 		__skb_trim(skb, snaplen);
 #endif
 
 	skb_set_owner_r(skb, sk);
+	skb->dev = NULL;
 	spin_lock(&sk->receive_queue.lock);
 	po->stats.tp_packets++;
 	__skb_queue_tail(&sk->receive_queue, skb);

Re: [PATCH 2/2] ipv4: Change rt->rt_iif encoding.

[David Miller]

From: Julian Anastasov <ja@ssi.bg>
Date: Tue, 24 Jul 2012 02:11:38 +0300 (EEST)

> skb_iif: ifindex of device we arrived on
> 
> 	If it has hidden semantic may be we can make this
> comment more specific, does it survive some loops?

Strangely I hadn't noticed this, and after the email I just sent
out I was going to look into adding such a value :-)

Great!

I'll respin my patches to use that thing, thanks Julian.

Re: [PATCH 2/2] ipv4: Change rt->rt_iif encoding.

[Julian Anastasov]

	Hello,

On Mon, 23 Jul 2012, David Miller wrote:

> From: David Miller <davem@davemloft.net>
> Date: Mon, 23 Jul 2012 14:07:37 -0700 (PDT)
> 
> > On input packet processing, rt->rt_iif will be zero if we should
> > use skb->dev->ifindex.
> > 
> > Since we access rt->rt_iif consistently via inet_iif(), that is
> > the only spot whose interpretation have to adjust.
> > 
> > Signed-off-by: David S. Miller <davem@davemloft.net>
> 
> Julian, as you seem to have feared, this turns out to not work.
> 
> We zap the skb->dev apparently, so I'll need to come up with
> a different scheme to handle this.

	I was just replying that I don't see any problems
with the 4 patches but when you say it, may be the net/sched
code will work with output device on forwarding, not input.
Is skb_iif a good source? From include/linux/skbuff.h:

skb_iif: ifindex of device we arrived on

	If it has hidden semantic may be we can make this
comment more specific, does it survive some loops?

	Anyways, the idea for new encoding of rt_iif is very good.

Regards

--
Julian Anastasov <ja@ssi.bg>

Re: [PATCH 2/2] ipv4: Change rt->rt_iif encoding.

[David Miller]

From: David Miller <davem@davemloft.net>
Date: Mon, 23 Jul 2012 16:05:41 -0700 (PDT)

> From: Julian Anastasov <ja@ssi.bg>
> Date: Tue, 24 Jul 2012 02:11:38 +0300 (EEST)
> 
>> skb_iif: ifindex of device we arrived on
>> 
>> 	If it has hidden semantic may be we can make this
>> comment more specific, does it survive some loops?
> 
> Strangely I hadn't noticed this, and after the email I just sent
> out I was going to look into adding such a value :-)
> 
> Great!
> 
> I'll respin my patches to use that thing, thanks Julian.

Hmmm, the problem is that when we decapsulate VLAN devices, we're left
with the parent device's index in skb->skb_iif.

That's what all of that "orig_dev" logic in __netif_receive_skb() is
all about.  The skb->dev is rewritten by vlan_do_receive() for that
case.

I wonder if we should just get rid of all of that orig_dev logic and
simply update skb->skb_iif every time we hit the code starting at
label "another_round"

I'll keep looking into this.

Re: [PATCH 2/2] ipv4: Change rt->rt_iif encoding.

[Julian Anastasov]

	Hello,

On Mon, 23 Jul 2012, David Miller wrote:

> Hmmm, the problem is that when we decapsulate VLAN devices, we're left
> with the parent device's index in skb->skb_iif.

	Not sure if it is a problem with VLANs, can be also
with some virtual devices but may be they use dev_forward_skb()
where skb_iif is zeroed.

> That's what all of that "orig_dev" logic in __netif_receive_skb() is
> all about.  The skb->dev is rewritten by vlan_do_receive() for that
> case.

	This is the part that I didn't know for skb_iif. I was
also worrying about ip_mc_output looping packets with skb_iif
because skb_clone copies the field but may be such loops
happen only for locally originated traffic where skb_iif starts
with 0.

	Still, the comment in ipmr_queue_xmit() and the
IPSKB_FORWARDED bit puzzles me:

         * RFC1584 teaches, that DVMRP/PIM router must deliver packets locally
         * not only before forwarding, but after forwarding on all output
         * interfaces. It is clear, if mrouter runs a multicasting

	ip_mr_forward preserves one copy to local app,
calls ipmr_queue_xmit() where packet can be looped?

	ip_mr_input():

        /* Packet is looped back after forward, it should not be
         * forwarded second time, but still can be delivered locally.
         */

	I really hope the case is for locally originated
multicast, not for packets received from network.

> I wonder if we should just get rid of all of that orig_dev logic and
> simply update skb->skb_iif every time we hit the code starting at
> label "another_round"

	I don't have opinion about this problem. I see your
new change for __netif_receive_skb, the skb_iif places are
something that I have to check for me...

Regards

--
Julian Anastasov <ja@ssi.bg>

Re: [PATCH 2/2] ipv4: Change rt->rt_iif encoding.

[David Miller]

From: Julian Anastasov <ja@ssi.bg>
Date: Tue, 24 Jul 2012 03:24:38 +0300 (EEST)

> On Mon, 23 Jul 2012, David Miller wrote:
> 
>> Hmmm, the problem is that when we decapsulate VLAN devices, we're left
>> with the parent device's index in skb->skb_iif.
> 
> 	Not sure if it is a problem with VLANs, can be also
> with some virtual devices but may be they use dev_forward_skb()
> where skb_iif is zeroed.

dev_forward_skb() gives the packet to netif_rx() which will thus send
the packet down to __netif_receive_skb() which will set the
skb->skb_iif to the new device's ifindex.  It will not stay at zero
:-)

> 	I was also worrying about ip_mc_output looping packets with
> skb_iif because skb_clone copies the field but may be such loops
> happen only for locally originated traffic where skb_iif starts with
> 0.

Loopback of multicast packets is done in ip_mc_output(), via
the clone that you mention, via dev_loopback_xmit().

dev_loopback_xmit() gives the packet to netif_rx_ni() which again
lands it back at __netif_receive_skb(), which (with my changes)
will adjust the skb->skb_iif to match whatever sits in skb->dev
at the time.

It should be alright.

Re: [PATCH 2/2] ipv4: Change rt->rt_iif encoding.

[Julian Anastasov]

	Hello,

On Mon, 23 Jul 2012, David Miller wrote:

> From: Julian Anastasov <ja@ssi.bg>
> Date: Tue, 24 Jul 2012 03:24:38 +0300 (EEST)
> 
> > On Mon, 23 Jul 2012, David Miller wrote:
> > 
> >> Hmmm, the problem is that when we decapsulate VLAN devices, we're left
> >> with the parent device's index in skb->skb_iif.
> > 
> > 	Not sure if it is a problem with VLANs, can be also
> > with some virtual devices but may be they use dev_forward_skb()
> > where skb_iif is zeroed.
> 
> dev_forward_skb() gives the packet to netif_rx() which will thus send
> the packet down to __netif_receive_skb() which will set the
> skb->skb_iif to the new device's ifindex.  It will not stay at zero
> :-)
> 
> > 	I was also worrying about ip_mc_output looping packets with
> > skb_iif because skb_clone copies the field but may be such loops
> > happen only for locally originated traffic where skb_iif starts with
> > 0.
> 
> Loopback of multicast packets is done in ip_mc_output(), via
> the clone that you mention, via dev_loopback_xmit().
> 
> dev_loopback_xmit() gives the packet to netif_rx_ni() which again
> lands it back at __netif_receive_skb(), which (with my changes)
> will adjust the skb->skb_iif to match whatever sits in skb->dev
> at the time.
> 
> It should be alright.

	Yes, I know that now it is set in all cases, I was
wondering why __netif_receive_skb was prepared to see
non-zero value. Please also check xfrm4_fill_dst, the
possible case where the new skb_iif usage can differ from
rt_iif is for forwarded packets where skb->dst is changed
with new version, for example:

ip_forward -> *xfrm*_policy_check* -> __xfrm_decode_session ->
_decode_session4 memsets flowi4_iif (now to get skb_iif).

ip_forward -> xfrm4_route_forward -> ... xfrm_lookup ->
... -> xfrm4_fill_dst now will use skb_iif ?

	XFRM is still magic for me and I'm not sure if
we need some other device instead of skb_iif. Should we
prefer dst->dev for output routes? For example:

static inline int inet_iif(const struct sk_buff *skb)
{
	struct rtable *rt = skb_rtable(skb);
	int iif = rt->rt_iif;

	if (iif)
		return iif;
	if (rt_is_output_route(rt))
		return rt->dst.dev->ifindex;
	return skb->skb_iif;
}

	but may be it is same if we restore the
rth->rt_iif	= orig_oif ? : dev_out->ifindex;

	code in __mkroute_output? By this way we will have
correct rt_iif at the time of routing call, before the
packet is looped via this device. Then skb_iif will remain
as default only for input routes. By this way we will be
less worried for places like xfrm or when skb->dst is
replaced in forwarding path. IPIP tunnels also replace
skb->dst but this can hurt only code like route4_classify.

Regards

--
Julian Anastasov <ja@ssi.bg>

Re: [PATCH 2/2] ipv4: Change rt->rt_iif encoding.

[Nicolas de Pesloüan]

Le 24/07/2012 01:14, David Miller a écrit :
[...]
> I wonder if we should just get rid of all of that orig_dev logic and
> simply update skb->skb_iif every time we hit the code starting at
> label "another_round"

It clearly depends on the exact meaning of orig_dev.

When we studied the usage of orig_dev before removing it from bonding, it was clear that two 
different meanings existed:

- From the bonding point of view, is was "the device one level below current device" (the slave, 
from the master's point of view).

- From the af_packet point of view, is was "the real original device that received the packet".

As bonding don't use orig_dev anymore, the remaining meaning should logically be "the real original 
device that received the packet". But as __netif_receive_skb() is recursively called in many cases, 
setting orig_dev to something new every time, this meaning is probably mostly inconsistent. As such, 
it sounds appropriate to remove orig_dev and use skb_iif instead.

	Nicolas.

Re: [PATCH 2/2] ipv4: Change rt->rt_iif encoding.

[David Miller]

From: Nicolas de Pesloüan <nicolas.2p.debian@gmail.com>
Date: Wed, 25 Jul 2012 00:13:55 +0200

> - From the af_packet point of view, is was "the real original device
> - that received the packet".
> 
> As bonding don't use orig_dev anymore, the remaining meaning should
> logically be "the real original device that received the packet". But
> as __netif_receive_skb() is recursively called in many cases, setting
> orig_dev to something new every time, this meaning is probably mostly
> inconsistent. As such, it sounds appropriate to remove orig_dev and
> use skb_iif instead.

I don't think we can, otherwise people who set po->origdev will no
longer get what they expect.

For the simpler cases of bonding and VLANs, it does currently behaved
as expected.

That's why I left it alone.

Re: [PATCH 2/2] ipv4: Change rt->rt_iif encoding.

[Nicolas de Pesloüan]

Le 25/07/2012 00:18, David Miller a écrit :
> From: Nicolas de Pesloüan<nicolas.2p.debian@gmail.com>
> Date: Wed, 25 Jul 2012 00:13:55 +0200
>
>> - From the af_packet point of view, is was "the real original device
>> - that received the packet".
>>
>> As bonding don't use orig_dev anymore, the remaining meaning should
>> logically be "the real original device that received the packet". But
>> as __netif_receive_skb() is recursively called in many cases, setting
>> orig_dev to something new every time, this meaning is probably mostly
>> inconsistent. As such, it sounds appropriate to remove orig_dev and
>> use skb_iif instead.
>
> I don't think we can, otherwise people who set po->origdev will no
> longer get what they expect.
>
> For the simpler cases of bonding and VLANs, it does currently behaved
> as expected.
>
> That's why I left it alone.

Do they get what they expect when stacking interfaces?

__netif_receive_skb starts with orig_dev = skb->dev. So when calling __netif_receive_skb 
recursively, after changing skb->dev, they get the packet several times, with a different orig_dev 
value?

Any way, both looks good to me.

	Nicolas.