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net: Dynamically allocate the per cpu counters for the loopback device.

PATCH Applied Eric W. Biederman 4 participants 16 messages Sep 26, 2007 – Sep 27, 2007

Subsystems (5)
Networking Network drivers netfilter IPv4/IPv6 +1 more subsystems
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Eric W. Biederman

author
#0 lore raw

PATCH 1/4 net: Dynamically allocate the per cpu counters for the loopback device.

This patch add support for dynamically allocating the statistics counters for the loopback device and adds appropriate device methods for allocating and freeing the loopback device.

This completes support for creating multiple instances of the loopback device, in preparation for creating per network namespace instances.

Signed-off-by Eric W. Biederman <[email protected]>
---
 drivers/net/loopback.c |   32 ++++++++++++++++++++++++++++----
 1 files changed, 28 insertions(+), 4 deletions(-)
drivers/net/loopback.c +28 -4
index 4b6f7b2..f3018bb 100644
@@ -62,7 +62,6 @@ struct pcpu_lstats {
 	unsigned long packets;
 	unsigned long bytes;
 };
-static DEFINE_PER_CPU(struct pcpu_lstats, pcpu_lstats);
 
 #define LOOPBACK_OVERHEAD (128 + MAX_HEADER + 16 + 16)
 

@@ -134,7 +133,7 @@ static void emulate_large_send_offload(struct sk_buff *skb)
  */
 static int loopback_xmit(struct sk_buff *skb, struct net_device *dev)
 {
-	struct pcpu_lstats *lb_stats;
+	struct pcpu_lstats *pcpu_lstats, *lb_stats;
 
 	skb_orphan(skb);
 

@@ -155,7 +154,8 @@ static int loopback_xmit(struct sk_buff *skb, struct net_device *dev)
 	dev->last_rx = jiffies;
 
 	/* it's OK to use __get_cpu_var() because BHs are off */
-	lb_stats = &__get_cpu_var(pcpu_lstats);
+	pcpu_lstats = netdev_priv(dev);
+	lb_stats = per_cpu_ptr(pcpu_lstats, smp_processor_id());
 	lb_stats->bytes += skb->len;
 	lb_stats->packets++;
 

@@ -166,15 +166,17 @@ static int loopback_xmit(struct sk_buff *skb, struct net_device *dev)
 
 static struct net_device_stats *get_stats(struct net_device *dev)
 {
+	const struct pcpu_lstats *pcpu_lstats;
 	struct net_device_stats *stats = &dev->stats;
 	unsigned long bytes = 0;
 	unsigned long packets = 0;
 	int i;
 
+	pcpu_lstats = netdev_priv(dev);
 	for_each_possible_cpu(i) {
 		const struct pcpu_lstats *lb_stats;
 
-		lb_stats = &per_cpu(pcpu_lstats, i);
+		lb_stats = per_cpu_ptr(pcpu_lstats, i);
 		bytes   += lb_stats->bytes;
 		packets += lb_stats->packets;
 	}

@@ -198,6 +200,26 @@ static const struct ethtool_ops loopback_ethtool_ops = {
 	.get_rx_csum		= always_on,
 };
 
+static int loopback_dev_init(struct net_device *dev)
+{
+	struct pcpu_lstats *lstats;
+
+	lstats = alloc_percpu(struct pcpu_lstats);
+	if (!lstats)
+		return -ENOMEM;
+
+	dev->priv = lstats;
+	return 0;
+}
+
+static void loopback_dev_free(struct net_device *dev)
+{
+	struct pcpu_lstats *lstats = netdev_priv(dev);
+
+	free_percpu(lstats);
+	free_netdev(dev);
+}
+
 /*
  * The loopback device is special. There is only one instance and
  * it is statically allocated. Don't do this for other devices.

@@ -225,6 +247,8 @@ static void loopback_setup(struct net_device *dev)
 		| NETIF_F_LLTX
 		| NETIF_F_NETNS_LOCAL,
 	dev->ethtool_ops	= &loopback_ethtool_ops;
+	dev->init = loopback_dev_init;
+	dev->destructor = loopback_dev_free;
 }
 
 /* Setup and register the loopback device. */
Signature · 1 line
1.5.3.rc6.17.g1911
author
#1 lore raw

PATCH 2/4 net ipv4: Remove unnecessary test for the loopback device from inetdev_destroy

Currently we never call unregister_netdev for the loopback device so it is impossible for us to reach inetdev_destroy with the loopback device. So the test in inetdev_destroy is unnecessary.

Further when testing with my network namespace patches removing unregistering the loopback device and calling inetdev_destroy works fine so there appears to be no reason for avoiding unregistering the loopback device.

Signed-off-by Eric W. Biederman <[email protected]>
---
 net/ipv4/devinet.c |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)
net/ipv4/devinet.c +0 -2
index affea9b..e7f2b02 100644
@@ -203,8 +203,6 @@ static void inetdev_destroy(struct in_device *in_dev)
 	ASSERT_RTNL();
 
 	dev = in_dev->dev;
-	if (dev == loopback_dev)
-		return;
 
 	in_dev->dead = 1;
Signature · 1 line
1.5.3.rc6.17.g1911
author
#2 lore raw

PATCH 3/4 net ipv4: When possible test for IFF_LOOPBACK and not dev == loopback_dev

Now that multiple loopback devices are becoming possible it makes the code a little cleaner and more maintainable to test if a deivice is th a loopback device by testing dev->flags & IFF_LOOPBACK instead of dev == loopback_dev.

Signed-off-by Eric W. Biederman <[email protected]>
---
 net/ipv4/devinet.c         |    4 ++--
 net/ipv4/ipconfig.c        |   10 +++++++---
 net/ipv4/ipvs/ip_vs_core.c |    2 +-
 3 files changed, 10 insertions(+), 6 deletions(-)
net/ipv4/devinet.c +2 -2
index e7f2b02..55d199e 100644
@@ -1059,7 +1059,7 @@ static int inetdev_event(struct notifier_block *this, unsigned long event,
 			in_dev = inetdev_init(dev);
 			if (!in_dev)
 				return notifier_from_errno(-ENOMEM);
-			if (dev == loopback_dev) {
+			if (dev->flags & IFF_LOOPBACK) {
 				IN_DEV_CONF_SET(in_dev, NOXFRM, 1);
 				IN_DEV_CONF_SET(in_dev, NOPOLICY, 1);
 			}

@@ -1075,7 +1075,7 @@ static int inetdev_event(struct notifier_block *this, unsigned long event,
 	case NETDEV_UP:
 		if (dev->mtu < 68)
 			break;
-		if (dev == loopback_dev) {
+		if (dev->flags & IFF_LOOPBACK) {
 			struct in_ifaddr *ifa;
 			if ((ifa = inet_alloc_ifa()) != NULL) {
 				ifa->ifa_local =
net/ipv4/ipconfig.c +7 -3
index 2d2e0cd..af5d5b3 100644
@@ -190,11 +190,15 @@ static int __init ic_open_devs(void)
 	rtnl_lock();
 
 	/* bring loopback device up first */
-	if (dev_change_flags(loopback_dev, loopback_dev->flags | IFF_UP) < 0)
-		printk(KERN_ERR "IP-Config: Failed to open %s\n", loopback_dev->name);
+	for_each_netdev(&init_net, dev) {
+		if (!(dev->flags & IFF_LOOPBACK))
+			continue;
+		if (dev_change_flags(dev, dev->flags | IFF_UP) < 0)
+			printk(KERN_ERR "IP-Config: Failed to open %s\n", dev->name);
+	}
 
 	for_each_netdev(&init_net, dev) {
-		if (dev == loopback_dev)
+		if (dev->flags & IFF_LOOPBACK)
 			continue;
 		if (user_dev_name[0] ? !strcmp(dev->name, user_dev_name) :
 		    (!(dev->flags & IFF_LOOPBACK) &&
net/ipv4/ipvs/ip_vs_core.c +1 -1
index 7450326..fbca2a2 100644
@@ -961,7 +961,7 @@ ip_vs_in(unsigned int hooknum, struct sk_buff **pskb,
 	 *	... don't know why 1st test DOES NOT include 2nd (?)
 	 */
 	if (unlikely(skb->pkt_type != PACKET_HOST
-		     || skb->dev == loopback_dev || skb->sk)) {
+		     || skb->dev->flags & IFF_LOOPBACK || skb->sk)) {
 		IP_VS_DBG(12, "packet type=%d proto=%d daddr=%d.%d.%d.%d ignored\n",
 			  skb->pkt_type,
 			  ip_hdr(skb)->protocol,
Signature · 1 line
1.5.3.rc6.17.g1911
author
#3 lore raw

PATCH 4/4 net: Make the loopback device per network namespace

This patch makes loopback_dev per network namespace. Adding code to create a different loopback device for each network namespace and adding the code to free a loopback device when a network namespace exits.

This patch modifies all users the loopback_dev so they access it as init_net.loopback_dev, keeping all of the code compiling and working. A later pass will be needed to update the users to use something other than the initial network namespace.

Signed-off-by Eric W. Biederman <[email protected]>
---
 drivers/net/loopback.c           |   26 +++++++++++++++++++++-----
 include/linux/netdevice.h        |    1 -
 include/net/net_namespace.h      |    3 +++
 net/core/dst.c                   |    5 +++--
 net/decnet/dn_dev.c              |    4 ++--
 net/decnet/dn_route.c            |   14 +++++++-------
 net/ipv4/route.c                 |   18 +++++++++---------
 net/ipv4/xfrm4_policy.c          |    2 +-
 net/ipv6/addrconf.c              |   18 +++++++++---------
 net/ipv6/netfilter/ip6t_REJECT.c |    2 +-
 net/ipv6/route.c                 |   12 ++++++------
 net/ipv6/xfrm6_policy.c          |    2 +-
 net/xfrm/xfrm_policy.c           |    2 +-
 13 files changed, 64 insertions(+), 45 deletions(-)
drivers/net/loopback.c +21 -5
index f3018bb..0f9d8c6 100644
@@ -57,6 +57,7 @@
 #include <linux/ip.h>
 #include <linux/tcp.h>
 #include <linux/percpu.h>
+#include <net/net_namespace.h>
 
 struct pcpu_lstats {
 	unsigned long packets;

@@ -252,7 +253,7 @@ static void loopback_setup(struct net_device *dev)
 }
 
 /* Setup and register the loopback device. */
-static int __init loopback_init(void)
+static int loopback_net_init(struct net *net)
 {
 	struct net_device *dev;
 	int err;

@@ -262,12 +263,13 @@ static int __init loopback_init(void)
 	if (!dev)
 		goto out;
 
+	dev->nd_net = net;
 	err = register_netdev(dev);
 	if (err)
 		goto out_free_netdev;
 
 	err = 0;
-	loopback_dev = dev;
+	net->loopback_dev = dev;
 
 out:
 	if (err)

@@ -279,7 +281,21 @@ out_free_netdev:
 	goto out;
 }
 
-fs_initcall(loopback_init);
+static void loopback_net_exit(struct net *net)
+{
+	struct net_device *dev = net->loopback_dev;
+
+	unregister_netdev(dev);
+}
+
+static struct pernet_operations loopback_net_ops = {
+       .init = loopback_net_init,
+       .exit = loopback_net_exit,
+};
+
+static int __init loopback_init(void)
+{
+	return register_pernet_device(&loopback_net_ops);
+}
 
-struct net_device *loopback_dev;
-EXPORT_SYMBOL(loopback_dev);
+fs_initcall(loopback_init);
include/linux/netdevice.h +0 -1
index 2088097..71cf409 100644
@@ -742,7 +742,6 @@ struct packet_type {
 #include <linux/interrupt.h>
 #include <linux/notifier.h>
 
-extern struct net_device		*loopback_dev;		/* The loopback */
 extern rwlock_t				dev_base_lock;		/* Device list lock */
include/net/net_namespace.h +3 -0
index 3ea4194..13b0e3b 100644
@@ -9,6 +9,7 @@
 #include <linux/list.h>
 
 struct proc_dir_entry;
+struct net_device;
 struct net {
 	atomic_t		count;		/* To decided when the network
 						 *  namespace should be freed.

@@ -23,6 +24,8 @@ struct net {
 	struct proc_dir_entry 	*proc_net_stat;
 	struct proc_dir_entry 	*proc_net_root;
 
+	struct net_device       *loopback_dev;          /* The loopback */
+
 	struct list_head 	dev_base_head;
 	struct hlist_head 	*dev_name_head;
 	struct hlist_head	*dev_index_head;
net/core/dst.c +3 -2
index ad5ffa1..16958e6 100644
@@ -18,6 +18,7 @@
 #include <linux/types.h>
 #include <net/net_namespace.h>
 
+#include <net/net_namespace.h>
 #include <net/dst.h>
 
 /*

@@ -278,11 +279,11 @@ static inline void dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 	if (!unregister) {
 		dst->input = dst->output = dst_discard;
 	} else {
-		dst->dev = loopback_dev;
+		dst->dev = init_net.loopback_dev;
 		dev_hold(dst->dev);
 		dev_put(dev);
 		if (dst->neighbour && dst->neighbour->dev == dev) {
-			dst->neighbour->dev = loopback_dev;
+			dst->neighbour->dev = init_net.loopback_dev;
 			dev_put(dev);
 			dev_hold(dst->neighbour->dev);
 		}
net/decnet/dn_dev.c +2 -2
index bcaf4c5..26130af 100644
@@ -869,10 +869,10 @@ last_chance:
 		rv = dn_dev_get_first(dev, addr);
 		read_unlock(&dev_base_lock);
 		dev_put(dev);
-		if (rv == 0 || dev == loopback_dev)
+		if (rv == 0 || dev == init_net.loopback_dev)
 			return rv;
 	}
-	dev = loopback_dev;
+	dev = init_net.loopback_dev;
 	dev_hold(dev);
 	goto last_chance;
 }
net/decnet/dn_route.c +7 -7
index 96fe0aa..b7ebf99 100644
@@ -887,7 +887,7 @@ static int dn_route_output_slow(struct dst_entry **pprt, const struct flowi *old
 					.scope = RT_SCOPE_UNIVERSE,
 				     } },
 			    .mark = oldflp->mark,
-			    .iif = loopback_dev->ifindex,
+			    .iif = init_net.loopback_dev->ifindex,
 			    .oif = oldflp->oif };
 	struct dn_route *rt = NULL;
 	struct net_device *dev_out = NULL, *dev;

@@ -904,7 +904,7 @@ static int dn_route_output_slow(struct dst_entry **pprt, const struct flowi *old
 		       "dn_route_output_slow: dst=%04x src=%04x mark=%d"
 		       " iif=%d oif=%d\n", dn_ntohs(oldflp->fld_dst),
 		       dn_ntohs(oldflp->fld_src),
-		       oldflp->mark, loopback_dev->ifindex, oldflp->oif);
+		       oldflp->mark, init_net.loopback_dev->ifindex, oldflp->oif);
 
 	/* If we have an output interface, verify its a DECnet device */
 	if (oldflp->oif) {

@@ -957,7 +957,7 @@ source_ok:
 		err = -EADDRNOTAVAIL;
 		if (dev_out)
 			dev_put(dev_out);
-		dev_out = loopback_dev;
+		dev_out = init_net.loopback_dev;
 		dev_hold(dev_out);
 		if (!fl.fld_dst) {
 			fl.fld_dst =

@@ -966,7 +966,7 @@ source_ok:
 			if (!fl.fld_dst)
 				goto out;
 		}
-		fl.oif = loopback_dev->ifindex;
+		fl.oif = init_net.loopback_dev->ifindex;
 		res.type = RTN_LOCAL;
 		goto make_route;
 	}

@@ -1012,7 +1012,7 @@ source_ok:
 					if (dev_out)
 						dev_put(dev_out);
 					if (dn_dev_islocal(neigh->dev, fl.fld_dst)) {
-						dev_out = loopback_dev;
+						dev_out = init_net.loopback_dev;
 						res.type = RTN_LOCAL;
 					} else {
 						dev_out = neigh->dev;

@@ -1033,7 +1033,7 @@ source_ok:
 		/* Possible improvement - check all devices for local addr */
 		if (dn_dev_islocal(dev_out, fl.fld_dst)) {
 			dev_put(dev_out);
-			dev_out = loopback_dev;
+			dev_out = init_net.loopback_dev;
 			dev_hold(dev_out);
 			res.type = RTN_LOCAL;
 			goto select_source;

@@ -1069,7 +1069,7 @@ select_source:
 			fl.fld_src = fl.fld_dst;
 		if (dev_out)
 			dev_put(dev_out);
-		dev_out = loopback_dev;
+		dev_out = init_net.loopback_dev;
 		dev_hold(dev_out);
 		fl.oif = dev_out->ifindex;
 		if (res.fi)
net/ipv4/route.c +9 -9
index ca2878d..2a9b363 100644
@@ -1402,8 +1402,8 @@ static void ipv4_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 {
 	struct rtable *rt = (struct rtable *) dst;
 	struct in_device *idev = rt->idev;
-	if (dev != loopback_dev && idev && idev->dev == dev) {
-		struct in_device *loopback_idev = in_dev_get(loopback_dev);
+	if (dev != init_net.loopback_dev && idev && idev->dev == dev) {
+		struct in_device *loopback_idev = in_dev_get(init_net.loopback_dev);
 		if (loopback_idev) {
 			rt->idev = loopback_idev;
 			in_dev_put(idev);

@@ -1555,7 +1555,7 @@ static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
 #endif
 	rth->rt_iif	=
 	rth->fl.iif	= dev->ifindex;
-	rth->u.dst.dev	= loopback_dev;
+	rth->u.dst.dev	= init_net.loopback_dev;
 	dev_hold(rth->u.dst.dev);
 	rth->idev	= in_dev_get(rth->u.dst.dev);
 	rth->fl.oif	= 0;

@@ -1812,7 +1812,7 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
 	if (res.type == RTN_LOCAL) {
 		int result;
 		result = fib_validate_source(saddr, daddr, tos,
-					     loopback_dev->ifindex,
+					     init_net.loopback_dev->ifindex,
 					     dev, &spec_dst, &itag);
 		if (result < 0)
 			goto martian_source;

@@ -1879,7 +1879,7 @@ local_input:
 #endif
 	rth->rt_iif	=
 	rth->fl.iif	= dev->ifindex;
-	rth->u.dst.dev	= loopback_dev;
+	rth->u.dst.dev	= init_net.loopback_dev;
 	dev_hold(rth->u.dst.dev);
 	rth->idev	= in_dev_get(rth->u.dst.dev);
 	rth->rt_gateway	= daddr;

@@ -2149,7 +2149,7 @@ static int ip_route_output_slow(struct rtable **rp, const struct flowi *oldflp)
 						  RT_SCOPE_UNIVERSE),
 				      } },
 			    .mark = oldflp->mark,
-			    .iif = loopback_dev->ifindex,
+			    .iif = init_net.loopback_dev->ifindex,
 			    .oif = oldflp->oif };
 	struct fib_result res;
 	unsigned flags = 0;

@@ -2243,9 +2243,9 @@ static int ip_route_output_slow(struct rtable **rp, const struct flowi *oldflp)
 			fl.fl4_dst = fl.fl4_src = htonl(INADDR_LOOPBACK);
 		if (dev_out)
 			dev_put(dev_out);
-		dev_out = loopback_dev;
+		dev_out = init_net.loopback_dev;
 		dev_hold(dev_out);
-		fl.oif = loopback_dev->ifindex;
+		fl.oif = init_net.loopback_dev->ifindex;
 		res.type = RTN_LOCAL;
 		flags |= RTCF_LOCAL;
 		goto make_route;

@@ -2290,7 +2290,7 @@ static int ip_route_output_slow(struct rtable **rp, const struct flowi *oldflp)
 			fl.fl4_src = fl.fl4_dst;
 		if (dev_out)
 			dev_put(dev_out);
-		dev_out = loopback_dev;
+		dev_out = init_net.loopback_dev;
 		dev_hold(dev_out);
 		fl.oif = dev_out->ifindex;
 		if (res.fi)
net/ipv4/xfrm4_policy.c +1 -1
index 29ab3de..329825c 100644
@@ -306,7 +306,7 @@ static void xfrm4_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 
 	xdst = (struct xfrm_dst *)dst;
 	if (xdst->u.rt.idev->dev == dev) {
-		struct in_device *loopback_idev = in_dev_get(loopback_dev);
+		struct in_device *loopback_idev = in_dev_get(init_net.loopback_dev);
 		BUG_ON(!loopback_idev);
 
 		do {
net/ipv6/addrconf.c +9 -9
index b43574f..6d5c3c2 100644
@@ -2410,7 +2410,7 @@ static int addrconf_ifdown(struct net_device *dev, int how)
 
 	ASSERT_RTNL();
 
-	if (dev == loopback_dev && how == 1)
+	if (dev == init_net.loopback_dev && how == 1)
 		how = 0;
 
 	rt6_ifdown(dev);

@@ -4212,19 +4212,19 @@ int __init addrconf_init(void)
 	 * device and it being up should be removed.
 	 */
 	rtnl_lock();
-	if (!ipv6_add_dev(loopback_dev))
+	if (!ipv6_add_dev(init_net.loopback_dev))
 		err = -ENOMEM;
 	rtnl_unlock();
 	if (err)
 		return err;
 
-	ip6_null_entry.u.dst.dev = loopback_dev;
-	ip6_null_entry.rt6i_idev = in6_dev_get(loopback_dev);
+	ip6_null_entry.u.dst.dev = init_net.loopback_dev;
+	ip6_null_entry.rt6i_idev = in6_dev_get(init_net.loopback_dev);
 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
-	ip6_prohibit_entry.u.dst.dev = loopback_dev;
-	ip6_prohibit_entry.rt6i_idev = in6_dev_get(loopback_dev);
-	ip6_blk_hole_entry.u.dst.dev = loopback_dev;
-	ip6_blk_hole_entry.rt6i_idev = in6_dev_get(loopback_dev);
+	ip6_prohibit_entry.u.dst.dev = init_net.loopback_dev;
+	ip6_prohibit_entry.rt6i_idev = in6_dev_get(init_net.loopback_dev);
+	ip6_blk_hole_entry.u.dst.dev = init_net.loopback_dev;
+	ip6_blk_hole_entry.rt6i_idev = in6_dev_get(init_net.loopback_dev);
 #endif
 
 	register_netdevice_notifier(&ipv6_dev_notf);

@@ -4279,7 +4279,7 @@ void __exit addrconf_cleanup(void)
 			continue;
 		addrconf_ifdown(dev, 1);
 	}
-	addrconf_ifdown(loopback_dev, 2);
+	addrconf_ifdown(init_net.loopback_dev, 2);
 
 	/*
 	 *	Check hash table.
net/ipv6/netfilter/ip6t_REJECT.c +1 -1
index 5086053..3fd08d5 100644
@@ -167,7 +167,7 @@ static inline void
 send_unreach(struct sk_buff *skb_in, unsigned char code, unsigned int hooknum)
 {
 	if (hooknum == NF_IP6_LOCAL_OUT && skb_in->dev == NULL)
-		skb_in->dev = loopback_dev;
+		skb_in->dev = init_net.loopback_dev;
 
 	icmpv6_send(skb_in, ICMPV6_DEST_UNREACH, code, 0, NULL);
 }
net/ipv6/route.c +6 -6
index a7a21a7..6ff19f9 100644
@@ -221,8 +221,8 @@ static void ip6_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 	struct rt6_info *rt = (struct rt6_info *)dst;
 	struct inet6_dev *idev = rt->rt6i_idev;
 
-	if (dev != loopback_dev && idev != NULL && idev->dev == dev) {
-		struct inet6_dev *loopback_idev = in6_dev_get(loopback_dev);
+	if (dev != init_net.loopback_dev && idev != NULL && idev->dev == dev) {
+		struct inet6_dev *loopback_idev = in6_dev_get(init_net.loopback_dev);
 		if (loopback_idev != NULL) {
 			rt->rt6i_idev = loopback_idev;
 			in6_dev_put(idev);

@@ -1185,12 +1185,12 @@ int ip6_route_add(struct fib6_config *cfg)
 	if ((cfg->fc_flags & RTF_REJECT) ||
 	    (dev && (dev->flags&IFF_LOOPBACK) && !(addr_type&IPV6_ADDR_LOOPBACK))) {
 		/* hold loopback dev/idev if we haven't done so. */
-		if (dev != loopback_dev) {
+		if (dev != init_net.loopback_dev) {
 			if (dev) {
 				dev_put(dev);
 				in6_dev_put(idev);
 			}
-			dev = loopback_dev;
+			dev = init_net.loopback_dev;
 			dev_hold(dev);
 			idev = in6_dev_get(dev);
 			if (!idev) {

@@ -1894,13 +1894,13 @@ struct rt6_info *addrconf_dst_alloc(struct inet6_dev *idev,
 	if (rt == NULL)
 		return ERR_PTR(-ENOMEM);
 
-	dev_hold(loopback_dev);
+	dev_hold(init_net.loopback_dev);
 	in6_dev_hold(idev);
 
 	rt->u.dst.flags = DST_HOST;
 	rt->u.dst.input = ip6_input;
 	rt->u.dst.output = ip6_output;
-	rt->rt6i_dev = loopback_dev;
+	rt->rt6i_dev = init_net.loopback_dev;
 	rt->rt6i_idev = idev;
 	rt->u.dst.metrics[RTAX_MTU-1] = ipv6_get_mtu(rt->rt6i_dev);
 	rt->u.dst.metrics[RTAX_ADVMSS-1] = ipv6_advmss(dst_mtu(&rt->u.dst));
net/ipv6/xfrm6_policy.c +1 -1
index cc07216..15aa4c5 100644
@@ -375,7 +375,7 @@ static void xfrm6_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 
 	xdst = (struct xfrm_dst *)dst;
 	if (xdst->u.rt6.rt6i_idev->dev == dev) {
-		struct inet6_dev *loopback_idev = in6_dev_get(loopback_dev);
+		struct inet6_dev *loopback_idev = in6_dev_get(init_net.loopback_dev);
 		BUG_ON(!loopback_idev);
 
 		do {
net/xfrm/xfrm_policy.c +1 -1
index d6dfd7d..76f172f 100644
@@ -1949,7 +1949,7 @@ static int stale_bundle(struct dst_entry *dst)
 void xfrm_dst_ifdown(struct dst_entry *dst, struct net_device *dev)
 {
 	while ((dst = dst->child) && dst->xfrm && dst->dev == dev) {
-		dst->dev = loopback_dev;
+		dst->dev = init_net.loopback_dev;
 		dev_hold(dst->dev);
 		dev_put(dev);
 	}
Signature · 1 line
1.5.3.rc6.17.g1911
maintainer Applied
#4 lore raw

Re: [PATCH 4/4] net: Make the loopback device per network namespace

From: [email protected] (Eric W. Biederman)
Date: Wed, 26 Sep 2007 18:00:20 -0600

Quoted 6 lines

This patch makes loopback_dev per network namespace. Adding code to create a different loopback device for each network namespace and adding the code to free a loopback device when a network namespace exits.

Quoted 7 lines

This patch modifies all users the loopback_dev so they access it as init_net.loopback_dev, keeping all of the code compiling and working. A later pass will be needed to update the users to use something other than the initial network namespace.

Signed-off-by Eric W. Biederman <[email protected]>

Applied to net-2.6.24, thanks Eric.

#5 lore raw

Re: [Devel] [PATCH 4/4] net: Make the loopback device per network namespace

In reply to Eric W. Biederman
Quoted 10 lines · Eric W. Biederman

This patch makes loopback_dev per network namespace. Adding code to create a different loopback device for each network namespace and adding the code to free a loopback device when a network namespace exits.

This patch modifies all users the loopback_dev so they access it as init_net.loopback_dev, keeping all of the code compiling and working. A later pass will be needed to update the users to use something other than the initial network namespace.

A pity that an important bit of explanation is missed. The initialization of loopback_dev is moved from a chain of devices (init_module) to a subsystem initialization to keep proper order, i.e. we must be sure that the initialization order is correct.

Regards,
Den

author
#6 lore raw

Re: [Devel] [PATCH 4/4] net: Make the loopback device per network namespace

Quoted 12 lines · Denis V. Lunev
Quoted 10 lines · Eric W. Biederman

This patch makes loopback_dev per network namespace. Adding code to create a different loopback device for each network namespace and adding the code to free a loopback device when a network namespace exits.

This patch modifies all users the loopback_dev so they access it as init_net.loopback_dev, keeping all of the code compiling and working. A later pass will be needed to update the users to use something other than the initial network namespace.

Quoted 4 lines

A pity that an important bit of explanation is missed. The initialization of loopback_dev is moved from a chain of devices (init_module) to a subsystem initialization to keep proper order, i.e. we must be sure that the initialization order is correct.

That didn't happen in the patch you mentioned. That happened when we started dynamically allocating the loopback device. That was the patch Daniel sent out a bit ago.

There are certainly some ordering issues and it may have helped to talk about them. But they are because things assume the loopback device is present. We have various bits of code that is around such as the dst_ifdown case that assumes if another network device is present the loopback device is present. To fulfill that assumption I guess that means we have both an initialization order dependency and a destruction order dependency.

The fact we were using module_init before actually appears to me to have been racy, but we got away with it because the actual data structure was statically allocated.

Since it appears that for a dynamically allocated loopback registering it first and unregistering it last is necessary
for routing. It is likely worth looking at this a little
more closely and making a guarantee. So we can make it easier for networking layers like ipv6, that want to memorize which device is the loopback device.

Eric

maintainer Applied
#7 lore raw

Re: [PATCH 3/4] net ipv4: When possible test for IFF_LOOPBACK and not dev == loopback_dev

In reply to Eric W. Biederman

From: [email protected] (Eric W. Biederman)
Date: Wed, 26 Sep 2007 17:58:21 -0600

Quoted 7 lines

Now that multiple loopback devices are becoming possible it makes the code a little cleaner and more maintainable to test if a deivice is th a loopback device by testing dev->flags & IFF_LOOPBACK instead of dev == loopback_dev.

Signed-off-by Eric W. Biederman <[email protected]>

Applied.

#8 lore raw

Re: [PATCH 3/4] net ipv4: When possible test for IFF_LOOPBACK and not dev == loopback_dev

In reply to Eric W. Biederman
Quoted 6 lines · Eric W. Biederman

Now that multiple loopback devices are becoming possible it makes the code a little cleaner and more maintainable to test if a deivice is th a loopback device by testing dev->flags & IFF_LOOPBACK instead of dev == loopback_dev.

Signed-off-by Eric W. Biederman <[email protected]>

Urs Thuermann posted the patch:

[PATCH 5/7] CAN: Add virtual CAN netdevice driver

This network driver set its flag to IFF_LOOPBACK for testing. Is it possible this can be a collision with your patch ?

author
#9 lore raw

Re: [PATCH 3/4] net ipv4: When possible test for IFF_LOOPBACK and not dev == loopback_dev

Quoted 9 lines · Daniel Lezcano
Quoted 6 lines · Eric W. Biederman

Now that multiple loopback devices are becoming possible it makes the code a little cleaner and more maintainable to test if a deivice is th a loopback device by testing dev->flags & IFF_LOOPBACK instead of dev == loopback_dev.

Signed-off-by Eric W. Biederman <[email protected]>
Quoted 6 lines

Urs Thuermann posted the patch:

[PATCH 5/7] CAN: Add virtual CAN netdevice driver

This network driver set its flag to IFF_LOOPBACK for testing. Is it possible this can be a collision with your patch ?

I have brought it up on that thread. As best as I tell the CAN usage of IFF_LOOPBACK will be a problem even without my patch. Assuming something other then the CAN layer will see the CAN devices.

The CAN documentations IFF_LOOPBACK should be set on all CAN devices.

It seems that the people who want high performance predictable CAN don't want this and the people who want something they can trace easily want this.

It sounds to me like CAN routers don't exist.

Anyway hopefully that usage can be resolved as that code is reviewed, and made ready to merge.

Eric

maintainer
#10 lore raw

Re: [PATCH 2/4] net ipv4: Remove unnecessary test for the loopback device from inetdev_destroy

In reply to Eric W. Biederman

From: [email protected] (Eric W. Biederman)
Date: Wed, 26 Sep 2007 17:55:29 -0600

Quoted 11 lines

Currently we never call unregister_netdev for the loopback device so it is impossible for us to reach inetdev_destroy with the loopback device. So the test in inetdev_destroy is unnecessary.

Further when testing with my network namespace patches removing unregistering the loopback device and calling inetdev_destroy works fine so there appears to be no reason for avoiding unregistering the loopback device.

Signed-off-by Eric W. Biederman <[email protected]>

Fair enough, applied to net-2.6.24

maintainer Applied
#11 lore raw
In reply to Eric W. Biederman

From: [email protected] (Eric W. Biederman)
Date: Wed, 26 Sep 2007 17:53:40 -0600

Quoted 9 lines

This patch add support for dynamically allocating the statistics counters for the loopback device and adds appropriate device methods for allocating and freeing the loopback device.

This completes support for creating multiple instances of the loopback device, in preparation for creating per network namespace instances.

Signed-off-by Eric W. Biederman <[email protected]>

Applied to net-2.6.24, thanks.

drivers/net/loopback.c static int loopback_xmit(struct sk_buff *skb, struct net_device *dev) · line 161

Quoted 10 lines
drivers/net/loopback.c +2 -1
@@ -155,7 +154,8 @@ static int loopback_xmit(struct sk_buff *skb, struct net_device *dev)
 	dev->last_rx = jiffies;
 
 	/* it's OK to use __get_cpu_var() because BHs are off */
-	lb_stats = &__get_cpu_var(pcpu_lstats);
+	pcpu_lstats = netdev_priv(dev);
+	lb_stats = per_cpu_ptr(pcpu_lstats, smp_processor_id());
 	lb_stats->bytes += skb->len;
 	lb_stats->packets++;

I'm going to add a followon change that gets rid of that comment about __get_cpu_var() since it is no longer relevant.

author
#12 lore raw
Quoted 19 lines · David Miller

From: [email protected] (Eric W. Biederman)
Date: Wed, 26 Sep 2007 17:53:40 -0600

Quoted 9 lines

This patch add support for dynamically allocating the statistics counters for the loopback device and adds appropriate device methods for allocating and freeing the loopback device.

This completes support for creating multiple instances of the loopback device, in preparation for creating per network namespace instances.

Signed-off-by Eric W. Biederman <[email protected]>

Applied to net-2.6.24, thanks.

Review static int loopback_xmit(struct sk_buff *skb, struct

Quoted 1 line
(quoted diff) +0 -0
@@ -155,7 +154,8 @@ static int loopback_xmit(struct sk_buff *skb, struct

net_device *dev)

Quoted 2 lines
drivers/net/loopback.c +0 -0
 	dev->last_rx = jiffies;
Quoted 11 lines

drivers/net/loopback.c static int loopback_xmit(struct sk_buff *skb, struct net_device *dev) · line 161

Quoted 7 lines
drivers/net/loopback.c +2 -1
 	/* it's OK to use __get_cpu_var() because BHs are off */
-	lb_stats = &__get_cpu_var(pcpu_lstats);
+	pcpu_lstats = netdev_priv(dev);
+	lb_stats = per_cpu_ptr(pcpu_lstats, smp_processor_id());
 	lb_stats->bytes += skb->len;
 	lb_stats->packets++;

I'm going to add a followon change that gets rid of that comment about __get_cpu_var() since it is no longer relevant.

Good point.

I'm not doing get_cpu/put_cpu so does the comment make sense in relationship to per_cpu_ptr?

Eric

maintainer
#13 lore raw

From: [email protected] (Eric W. Biederman)
Date: Thu, 27 Sep 2007 01:48:00 -0600

Quoted 2 lines

I'm not doing get_cpu/put_cpu so does the comment make sense in relationship to per_cpu_ptr?

It is possible. But someone would need to go check for sure.

author
#14 lore raw
Quoted 8 lines · David Miller

From: [email protected] (Eric W. Biederman)
Date: Thu, 27 Sep 2007 01:48:00 -0600

Quoted 2 lines

I'm not doing get_cpu/put_cpu so does the comment make sense in relationship to per_cpu_ptr?

It is possible. But someone would need to go check for sure.

Verified.

hard_start_xmit is called inside of a rcu_read_lock_bh(),rcu_read_unlock_bh() pair. Which means the code will only run on one cpu.

Therefore we do not need get_cpu/put_cpu.

In addition per_cpu_ptr is valid. As it is just a lookup into a NR_CPUS sized array by smp_processor_id() to return the address of the specific cpu.

The only difference between per_cpu_ptr and __get_cpu_var() are the implementation details between statically allocated and dynamically allocated per cpu state.

So the comment is still valid, and still interesting it just should say per_cpu_ptr instead of __get_cpu_var.

Signed-off-by "Eric W. Biederman" <[email protected]>

---

drivers/net/loopback.c +1 -1
index 0f9d8c6..756e267 100644
@@ -154,7 +154,7 @@ static int loopback_xmit(struct sk_buff *skb, struct net_device *dev)
 #endif
 	dev->last_rx = jiffies;
 
-	/* it's OK to use __get_cpu_var() because BHs are off */
+	/* it's OK to use per_cpu_ptr() because BHs are off */
 	pcpu_lstats = netdev_priv(dev);
 	lb_stats = per_cpu_ptr(pcpu_lstats, smp_processor_id());
 	lb_stats->bytes += skb->len;
maintainer
#15 lore raw

From: [email protected] (Eric W. Biederman)
Date: Thu, 27 Sep 2007 14:44:37 -0600

Quoted 23 lines
Quoted 8 lines · David Miller

From: [email protected] (Eric W. Biederman)
Date: Thu, 27 Sep 2007 01:48:00 -0600

Quoted 2 lines

I'm not doing get_cpu/put_cpu so does the comment make sense in relationship to per_cpu_ptr?

It is possible. But someone would need to go check for sure.

Verified.

hard_start_xmit is called inside of a rcu_read_lock_bh(),rcu_read_unlock_bh() pair. Which means the code will only run on one cpu.

Therefore we do not need get_cpu/put_cpu.

In addition per_cpu_ptr is valid. As it is just a lookup into a NR_CPUS sized array by smp_processor_id() to return the address of the specific cpu.

Quoted 8 lines

The only difference between per_cpu_ptr and __get_cpu_var() are the implementation details between statically allocated and dynamically allocated per cpu state.

So the comment is still valid, and still interesting it just should say per_cpu_ptr instead of __get_cpu_var.

Signed-off-by "Eric W. Biederman" <[email protected]>

I've already removed the comment, so you'll have to give me a patch that adds it back with the new content :-)