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Merge branch 'ipv6-loopback'

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Eric Dumazet says:

====================
ipv6: remove addrconf reliance on loopback

Second patch in this series removes IPv6 requirement about the netns
loopback device being the last device being dismantled.

This was needed because rt6_uncached_list_flush_dev()
and ip6_dst_ifdown() had to switch dst dev to a known
device (loopback).

Instead of loopback, we can use the (hidden) blackhole_netdev
which is also always there.

This will allow future simplfications of netdev_run_to()
and other parts of the stack like default_device_exit_batch().

Last two patches are optimizations for both IP families.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2022-02-11 11:44:27 +00:00
commit c002496bab
5 changed files with 64 additions and 72 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

3
include/net/ip6_fib.h
View file

@ -367,9 +367,8 @@ struct rt6_statistics {
__u32 fib_rt_cache; /* cached rt entries in exception table */
__u32 fib_discarded_routes; /* total number of routes delete */
/* The following stats are not protected by any lock */
/* The following stat is not protected by any lock */
atomic_t fib_rt_alloc; /* total number of routes alloced */
atomic_t fib_rt_uncache; /* rt entries in uncached list */
};
#define RTN_TL_ROOT 0x0001

12
net/ipv4/route.c
View file

@ -1485,6 +1485,7 @@ static bool rt_cache_route(struct fib_nh_common *nhc, struct rtable *rt)
struct uncached_list {
spinlock_t lock;
struct list_head head;
struct list_head quarantine;
};
static DEFINE_PER_CPU_ALIGNED(struct uncached_list, rt_uncached_list);
@ -1506,7 +1507,7 @@ void rt_del_uncached_list(struct rtable *rt)
struct uncached_list *ul = rt->rt_uncached_list;
spin_lock_bh(&ul->lock);
list_del(&rt->rt_uncached);
list_del_init(&rt->rt_uncached);
spin_unlock_bh(&ul->lock);
}
}
@ -1521,20 +1522,24 @@ static void ipv4_dst_destroy(struct dst_entry *dst)
void rt_flush_dev(struct net_device *dev)
{
struct rtable *rt;
struct rtable *rt, *safe;
int cpu;
for_each_possible_cpu(cpu) {
struct uncached_list *ul = &per_cpu(rt_uncached_list, cpu);
if (list_empty(&ul->head))
continue;
spin_lock_bh(&ul->lock);
list_for_each_entry(rt, &ul->head, rt_uncached) {
list_for_each_entry_safe(rt, safe, &ul->head, rt_uncached) {
if (rt->dst.dev != dev)
continue;
rt->dst.dev = blackhole_netdev;
dev_replace_track(dev, blackhole_netdev,
&rt->dst.dev_tracker,
GFP_ATOMIC);
list_move(&rt->rt_uncached, &ul->quarantine);
}
spin_unlock_bh(&ul->lock);
}
@ -3706,6 +3711,7 @@ int __init ip_rt_init(void)
struct uncached_list *ul = &per_cpu(rt_uncached_list, cpu);
INIT_LIST_HEAD(&ul->head);
INIT_LIST_HEAD(&ul->quarantine);
spin_lock_init(&ul->lock);
}
#ifdef CONFIG_IP_ROUTE_CLASSID

30
net/ipv6/addrconf.c
View file

@ -372,7 +372,7 @@ static struct inet6_dev *ipv6_add_dev(struct net_device *dev)
ASSERT_RTNL();
if (dev->mtu < IPV6_MIN_MTU)
if (dev->mtu < IPV6_MIN_MTU && dev != blackhole_netdev)
return ERR_PTR(-EINVAL);
ndev = kzalloc(sizeof(struct inet6_dev), GFP_KERNEL);
@ -400,6 +400,7 @@ static struct inet6_dev *ipv6_add_dev(struct net_device *dev)
/* We refer to the device */
dev_hold_track(dev, &ndev->dev_tracker, GFP_KERNEL);
if (dev != blackhole_netdev) {
if (snmp6_alloc_dev(ndev) < 0) {
netdev_dbg(dev, "%s: cannot allocate memory for statistics\n",
__func__);
@ -414,7 +415,7 @@ static struct inet6_dev *ipv6_add_dev(struct net_device *dev)
__func__, dev->name);
goto err_release;
}
}
/* One reference from device. */
refcount_set(&ndev->refcnt, 1);
@ -445,15 +446,18 @@ static struct inet6_dev *ipv6_add_dev(struct net_device *dev)
ipv6_mc_init_dev(ndev);
ndev->tstamp = jiffies;
if (dev != blackhole_netdev) {
err = addrconf_sysctl_register(ndev);
if (err) {
ipv6_mc_destroy_dev(ndev);
snmp6_unregister_dev(ndev);
goto err_release;
}
}
/* protected by rtnl_lock */
rcu_assign_pointer(dev->ip6_ptr, ndev);
if (dev != blackhole_netdev) {
/* Join interface-local all-node multicast group */
ipv6_dev_mc_inc(dev, &in6addr_interfacelocal_allnodes);
@ -463,7 +467,7 @@ static struct inet6_dev *ipv6_add_dev(struct net_device *dev)
/* Join all-router multicast group if forwarding is set */
if (ndev->cnf.forwarding && (dev->flags & IFF_MULTICAST))
ipv6_dev_mc_inc(dev, &in6addr_linklocal_allrouters);
}
return ndev;
err_release:
@ -7233,26 +7237,8 @@ int __init addrconf_init(void)
goto out_nowq;
}
/* The addrconf netdev notifier requires that loopback_dev
* has it's ipv6 private information allocated and setup
* before it can bring up and give link-local addresses
* to other devices which are up.
*
* Unfortunately, loopback_dev is not necessarily the first
* entry in the global dev_base list of net devices. In fact,
* it is likely to be the very last entry on that list.
* So this causes the notifier registry below to try and
* give link-local addresses to all devices besides loopback_dev
* first, then loopback_dev, which cases all the non-loopback_dev
* devices to fail to get a link-local address.
*
* So, as a temporary fix, allocate the ipv6 structure for
* loopback_dev first by hand.
* Longer term, all of the dependencies ipv6 has upon the loopback
* device and it being up should be removed.
*/
rtnl_lock();
idev = ipv6_add_dev(init_net.loopback_dev);
idev = ipv6_add_dev(blackhole_netdev);
rtnl_unlock();
if (IS_ERR(idev)) {
err = PTR_ERR(idev);

42
net/ipv6/route.c
View file

@ -130,6 +130,7 @@ static struct fib6_info *rt6_get_route_info(struct net *net,
struct uncached_list {
spinlock_t lock;
struct list_head head;
struct list_head quarantine;
};
static DEFINE_PER_CPU_ALIGNED(struct uncached_list, rt6_uncached_list);
@ -149,35 +150,34 @@ void rt6_uncached_list_del(struct rt6_info *rt)
{
if (!list_empty(&rt->rt6i_uncached)) {
struct uncached_list *ul = rt->rt6i_uncached_list;
struct net *net = dev_net(rt->dst.dev);
spin_lock_bh(&ul->lock);
list_del(&rt->rt6i_uncached);
atomic_dec(&net->ipv6.rt6_stats->fib_rt_uncache);
list_del_init(&rt->rt6i_uncached);
spin_unlock_bh(&ul->lock);
}
}
static void rt6_uncached_list_flush_dev(struct net *net, struct net_device *dev)
static void rt6_uncached_list_flush_dev(struct net_device *dev)
{
struct net_device *loopback_dev = net->loopback_dev;
int cpu;
if (dev == loopback_dev)
return;
for_each_possible_cpu(cpu) {
struct uncached_list *ul = per_cpu_ptr(&rt6_uncached_list, cpu);
struct rt6_info *rt;
struct rt6_info *rt, *safe;
if (list_empty(&ul->head))
continue;
spin_lock_bh(&ul->lock);
list_for_each_entry(rt, &ul->head, rt6i_uncached) {
list_for_each_entry_safe(rt, safe, &ul->head, rt6i_uncached) {
struct inet6_dev *rt_idev = rt->rt6i_idev;
struct net_device *rt_dev = rt->dst.dev;
bool handled = false;
if (rt_idev->dev == dev) {
rt->rt6i_idev = in6_dev_get(loopback_dev);
rt->rt6i_idev = in6_dev_get(blackhole_netdev);
in6_dev_put(rt_idev);
handled = true;
}
if (rt_dev == dev) {
@ -185,7 +185,11 @@ static void rt6_uncached_list_flush_dev(struct net *net, struct net_device *dev)
dev_replace_track(rt_dev, blackhole_netdev,
&rt->dst.dev_tracker,
GFP_ATOMIC);
handled = true;
}
if (handled)
list_move(&rt->rt6i_uncached,
&ul->quarantine);
}
spin_unlock_bh(&ul->lock);
}
@ -373,13 +377,12 @@ 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;
struct net_device *loopback_dev =
dev_net(dev)->loopback_dev;
if (idev && idev->dev != loopback_dev) {
struct inet6_dev *loopback_idev = in6_dev_get(loopback_dev);
if (loopback_idev) {
rt->rt6i_idev = loopback_idev;
if (idev && idev->dev != blackhole_netdev) {
struct inet6_dev *blackhole_idev = in6_dev_get(blackhole_netdev);
if (blackhole_idev) {
rt->rt6i_idev = blackhole_idev;
in6_dev_put(idev);
}
}
@ -2244,7 +2247,6 @@ struct rt6_info *ip6_pol_route(struct net *net, struct fib6_table *table,
* if caller sets RT6_LOOKUP_F_DST_NOREF flag.
*/
rt6_uncached_list_add(rt);
atomic_inc(&net->ipv6.rt6_stats->fib_rt_uncache);
rcu_read_unlock();
return rt;
@ -3287,7 +3289,6 @@ struct dst_entry *icmp6_dst_alloc(struct net_device *dev,
* do proper release of the net_device
*/
rt6_uncached_list_add(rt);
atomic_inc(&net->ipv6.rt6_stats->fib_rt_uncache);
dst = xfrm_lookup(net, &rt->dst, flowi6_to_flowi(fl6), NULL, 0);
@ -4896,7 +4897,7 @@ void rt6_sync_down_dev(struct net_device *dev, unsigned long event)
void rt6_disable_ip(struct net_device *dev, unsigned long event)
{
rt6_sync_down_dev(dev, event);
rt6_uncached_list_flush_dev(dev_net(dev), dev);
rt6_uncached_list_flush_dev(dev);
neigh_ifdown(&nd_tbl, dev);
}
@ -6736,6 +6737,7 @@ int __init ip6_route_init(void)
struct uncached_list *ul = per_cpu_ptr(&rt6_uncached_list, cpu);
INIT_LIST_HEAD(&ul->head);
INIT_LIST_HEAD(&ul->quarantine);
spin_lock_init(&ul->lock);
}

1
net/ipv6/xfrm6_policy.c
View file

@ -92,7 +92,6 @@ static int xfrm6_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
xdst->u.rt6.rt6i_src = rt->rt6i_src;
INIT_LIST_HEAD(&xdst->u.rt6.rt6i_uncached);
rt6_uncached_list_add(&xdst->u.rt6);
atomic_inc(&dev_net(dev)->ipv6.rt6_stats->fib_rt_uncache);
return 0;
}