net: replace dst_cache ip6_tunnel implementation with the generic one
This also fix a potential race into the existing tunnel code, which
could lead to the wrong dst to be permanenty cached:
CPU1: CPU2:
<xmit on ip6_tunnel>
<cache lookup fails>
dst = ip6_route_output(...)
<tunnel params are changed via nl>
dst_cache_reset() // no effect,
// the cache is empty
dst_cache_set() // the wrong dst
// is permanenty stored
// into the cache
With the new dst implementation the above race is not possible
since the first cache lookup after dst_cache_reset will fail due
to the timestamp check
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Suggested-and-acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index 137fca4..3f3aabd 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -122,97 +122,6 @@
return &dev->stats;
}
-/*
- * Locking : hash tables are protected by RCU and RTNL
- */
-
-static void ip6_tnl_per_cpu_dst_set(struct ip6_tnl_dst *idst,
- struct dst_entry *dst)
-{
- write_seqlock_bh(&idst->lock);
- dst_release(rcu_dereference_protected(
- idst->dst,
- lockdep_is_held(&idst->lock.lock)));
- if (dst) {
- dst_hold(dst);
- idst->cookie = rt6_get_cookie((struct rt6_info *)dst);
- } else {
- idst->cookie = 0;
- }
- rcu_assign_pointer(idst->dst, dst);
- write_sequnlock_bh(&idst->lock);
-}
-
-struct dst_entry *ip6_tnl_dst_get(struct ip6_tnl *t)
-{
- struct ip6_tnl_dst *idst;
- struct dst_entry *dst;
- unsigned int seq;
- u32 cookie;
-
- idst = raw_cpu_ptr(t->dst_cache);
-
- rcu_read_lock();
- do {
- seq = read_seqbegin(&idst->lock);
- dst = rcu_dereference(idst->dst);
- cookie = idst->cookie;
- } while (read_seqretry(&idst->lock, seq));
-
- if (dst && !atomic_inc_not_zero(&dst->__refcnt))
- dst = NULL;
- rcu_read_unlock();
-
- if (dst && dst->obsolete && !dst->ops->check(dst, cookie)) {
- ip6_tnl_per_cpu_dst_set(idst, NULL);
- dst_release(dst);
- dst = NULL;
- }
- return dst;
-}
-EXPORT_SYMBOL_GPL(ip6_tnl_dst_get);
-
-void ip6_tnl_dst_reset(struct ip6_tnl *t)
-{
- int i;
-
- for_each_possible_cpu(i)
- ip6_tnl_per_cpu_dst_set(per_cpu_ptr(t->dst_cache, i), NULL);
-}
-EXPORT_SYMBOL_GPL(ip6_tnl_dst_reset);
-
-void ip6_tnl_dst_set(struct ip6_tnl *t, struct dst_entry *dst)
-{
- ip6_tnl_per_cpu_dst_set(raw_cpu_ptr(t->dst_cache), dst);
-
-}
-EXPORT_SYMBOL_GPL(ip6_tnl_dst_set);
-
-void ip6_tnl_dst_destroy(struct ip6_tnl *t)
-{
- if (!t->dst_cache)
- return;
-
- ip6_tnl_dst_reset(t);
- free_percpu(t->dst_cache);
-}
-EXPORT_SYMBOL_GPL(ip6_tnl_dst_destroy);
-
-int ip6_tnl_dst_init(struct ip6_tnl *t)
-{
- int i;
-
- t->dst_cache = alloc_percpu(struct ip6_tnl_dst);
- if (!t->dst_cache)
- return -ENOMEM;
-
- for_each_possible_cpu(i)
- seqlock_init(&per_cpu_ptr(t->dst_cache, i)->lock);
-
- return 0;
-}
-EXPORT_SYMBOL_GPL(ip6_tnl_dst_init);
-
/**
* ip6_tnl_lookup - fetch tunnel matching the end-point addresses
* @remote: the address of the tunnel exit-point
@@ -329,7 +238,7 @@
{
struct ip6_tnl *t = netdev_priv(dev);
- ip6_tnl_dst_destroy(t);
+ dst_cache_destroy(&t->dst_cache);
free_percpu(dev->tstats);
free_netdev(dev);
}
@@ -462,7 +371,7 @@
RCU_INIT_POINTER(ip6n->tnls_wc[0], NULL);
else
ip6_tnl_unlink(ip6n, t);
- ip6_tnl_dst_reset(t);
+ dst_cache_reset(&t->dst_cache);
dev_put(dev);
}
@@ -1069,7 +978,7 @@
memcpy(&fl6->daddr, addr6, sizeof(fl6->daddr));
neigh_release(neigh);
} else if (!fl6->flowi6_mark)
- dst = ip6_tnl_dst_get(t);
+ dst = dst_cache_get(&t->dst_cache);
if (!ip6_tnl_xmit_ctl(t, &fl6->saddr, &fl6->daddr))
goto tx_err_link_failure;
@@ -1133,7 +1042,7 @@
}
if (!fl6->flowi6_mark && ndst)
- ip6_tnl_dst_set(t, ndst);
+ dst_cache_set_ip6(&t->dst_cache, ndst, &fl6->saddr);
skb_dst_set(skb, dst);
skb->transport_header = skb->network_header;
@@ -1366,7 +1275,7 @@
t->parms.flowinfo = p->flowinfo;
t->parms.link = p->link;
t->parms.proto = p->proto;
- ip6_tnl_dst_reset(t);
+ dst_cache_reset(&t->dst_cache);
ip6_tnl_link_config(t);
return 0;
}
@@ -1637,7 +1546,7 @@
if (!dev->tstats)
return -ENOMEM;
- ret = ip6_tnl_dst_init(t);
+ ret = dst_cache_init(&t->dst_cache, GFP_KERNEL);
if (ret) {
free_percpu(dev->tstats);
dev->tstats = NULL;