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>
This commit is contained in:
Paolo Abeni
David S. Miller
parent
911362c70d
commit
607f725f6f
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@ -6,6 +6,7 @@
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#include <linux/if_tunnel.h>
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#include <linux/ip6_tunnel.h>
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#include <net/ip_tunnels.h>
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#include <net/dst_cache.h>
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#define IP6TUNNEL_ERR_TIMEO (30*HZ)
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@ -33,12 +34,6 @@ struct __ip6_tnl_parm {
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__be32 o_key;
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};
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struct ip6_tnl_dst {
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seqlock_t lock;
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struct dst_entry __rcu *dst;
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u32 cookie;
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};
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/* IPv6 tunnel */
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struct ip6_tnl {
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struct ip6_tnl __rcu *next; /* next tunnel in list */
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@ -46,7 +41,7 @@ struct ip6_tnl {
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struct net *net; /* netns for packet i/o */
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struct __ip6_tnl_parm parms; /* tunnel configuration parameters */
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struct flowi fl; /* flowi template for xmit */
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struct ip6_tnl_dst __percpu *dst_cache; /* cached dst */
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struct dst_cache dst_cache; /* cached dst */
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int err_count;
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unsigned long err_time;
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@ -66,11 +61,6 @@ struct ipv6_tlv_tnl_enc_lim {
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__u8 encap_limit; /* tunnel encapsulation limit */
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} __packed;
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struct dst_entry *ip6_tnl_dst_get(struct ip6_tnl *t);
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int ip6_tnl_dst_init(struct ip6_tnl *t);
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void ip6_tnl_dst_destroy(struct ip6_tnl *t);
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void ip6_tnl_dst_reset(struct ip6_tnl *t);
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void ip6_tnl_dst_set(struct ip6_tnl *t, struct dst_entry *dst);
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int ip6_tnl_rcv_ctl(struct ip6_tnl *t, const struct in6_addr *laddr,
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const struct in6_addr *raddr);
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int ip6_tnl_xmit_ctl(struct ip6_tnl *t, const struct in6_addr *laddr,
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@ -207,6 +207,7 @@ config IPV6_NDISC_NODETYPE
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config IPV6_TUNNEL
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tristate "IPv6: IP-in-IPv6 tunnel (RFC2473)"
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select INET6_TUNNEL
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select DST_CACHE
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---help---
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Support for IPv6-in-IPv6 and IPv4-in-IPv6 tunnels described in
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RFC 2473.
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@ -360,7 +360,7 @@ static void ip6gre_tunnel_uninit(struct net_device *dev)
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struct ip6gre_net *ign = net_generic(t->net, ip6gre_net_id);
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ip6gre_tunnel_unlink(ign, t);
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ip6_tnl_dst_reset(t);
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dst_cache_reset(&t->dst_cache);
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dev_put(dev);
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}
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@ -633,7 +633,7 @@ static netdev_tx_t ip6gre_xmit2(struct sk_buff *skb,
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}
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if (!fl6->flowi6_mark)
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dst = ip6_tnl_dst_get(tunnel);
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dst = dst_cache_get(&tunnel->dst_cache);
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if (!dst) {
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dst = ip6_route_output(net, NULL, fl6);
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@ -702,7 +702,7 @@ static netdev_tx_t ip6gre_xmit2(struct sk_buff *skb,
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}
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if (!fl6->flowi6_mark && ndst)
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ip6_tnl_dst_set(tunnel, ndst);
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dst_cache_set_ip6(&tunnel->dst_cache, ndst, &fl6->saddr);
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skb_dst_set(skb, dst);
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proto = NEXTHDR_GRE;
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@ -1009,7 +1009,7 @@ static int ip6gre_tnl_change(struct ip6_tnl *t,
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t->parms.o_key = p->o_key;
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t->parms.i_flags = p->i_flags;
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t->parms.o_flags = p->o_flags;
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ip6_tnl_dst_reset(t);
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dst_cache_reset(&t->dst_cache);
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ip6gre_tnl_link_config(t, set_mtu);
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return 0;
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}
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@ -1219,7 +1219,7 @@ static void ip6gre_dev_free(struct net_device *dev)
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{
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struct ip6_tnl *t = netdev_priv(dev);
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ip6_tnl_dst_destroy(t);
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dst_cache_destroy(&t->dst_cache);
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free_percpu(dev->tstats);
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free_netdev(dev);
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}
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@ -1257,7 +1257,7 @@ static int ip6gre_tunnel_init_common(struct net_device *dev)
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if (!dev->tstats)
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return -ENOMEM;
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ret = ip6_tnl_dst_init(tunnel);
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ret = dst_cache_init(&tunnel->dst_cache, GFP_KERNEL);
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if (ret) {
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free_percpu(dev->tstats);
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dev->tstats = NULL;
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@ -122,97 +122,6 @@ static struct net_device_stats *ip6_get_stats(struct net_device *dev)
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return &dev->stats;
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}
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/*
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* Locking : hash tables are protected by RCU and RTNL
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*/
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static void ip6_tnl_per_cpu_dst_set(struct ip6_tnl_dst *idst,
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struct dst_entry *dst)
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{
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write_seqlock_bh(&idst->lock);
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dst_release(rcu_dereference_protected(
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idst->dst,
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lockdep_is_held(&idst->lock.lock)));
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if (dst) {
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dst_hold(dst);
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idst->cookie = rt6_get_cookie((struct rt6_info *)dst);
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} else {
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idst->cookie = 0;
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}
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rcu_assign_pointer(idst->dst, dst);
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write_sequnlock_bh(&idst->lock);
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}
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struct dst_entry *ip6_tnl_dst_get(struct ip6_tnl *t)
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{
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struct ip6_tnl_dst *idst;
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struct dst_entry *dst;
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unsigned int seq;
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u32 cookie;
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idst = raw_cpu_ptr(t->dst_cache);
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rcu_read_lock();
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do {
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seq = read_seqbegin(&idst->lock);
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dst = rcu_dereference(idst->dst);
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cookie = idst->cookie;
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} while (read_seqretry(&idst->lock, seq));
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if (dst && !atomic_inc_not_zero(&dst->__refcnt))
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dst = NULL;
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rcu_read_unlock();
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if (dst && dst->obsolete && !dst->ops->check(dst, cookie)) {
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ip6_tnl_per_cpu_dst_set(idst, NULL);
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dst_release(dst);
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dst = NULL;
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}
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return dst;
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}
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EXPORT_SYMBOL_GPL(ip6_tnl_dst_get);
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void ip6_tnl_dst_reset(struct ip6_tnl *t)
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{
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int i;
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for_each_possible_cpu(i)
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ip6_tnl_per_cpu_dst_set(per_cpu_ptr(t->dst_cache, i), NULL);
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}
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EXPORT_SYMBOL_GPL(ip6_tnl_dst_reset);
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void ip6_tnl_dst_set(struct ip6_tnl *t, struct dst_entry *dst)
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{
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ip6_tnl_per_cpu_dst_set(raw_cpu_ptr(t->dst_cache), dst);
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}
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EXPORT_SYMBOL_GPL(ip6_tnl_dst_set);
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void ip6_tnl_dst_destroy(struct ip6_tnl *t)
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{
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if (!t->dst_cache)
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return;
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ip6_tnl_dst_reset(t);
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free_percpu(t->dst_cache);
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}
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EXPORT_SYMBOL_GPL(ip6_tnl_dst_destroy);
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int ip6_tnl_dst_init(struct ip6_tnl *t)
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{
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int i;
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t->dst_cache = alloc_percpu(struct ip6_tnl_dst);
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if (!t->dst_cache)
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return -ENOMEM;
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for_each_possible_cpu(i)
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seqlock_init(&per_cpu_ptr(t->dst_cache, i)->lock);
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return 0;
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}
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EXPORT_SYMBOL_GPL(ip6_tnl_dst_init);
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/**
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* ip6_tnl_lookup - fetch tunnel matching the end-point addresses
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* @remote: the address of the tunnel exit-point
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@ -329,7 +238,7 @@ static void ip6_dev_free(struct net_device *dev)
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{
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struct ip6_tnl *t = netdev_priv(dev);
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ip6_tnl_dst_destroy(t);
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dst_cache_destroy(&t->dst_cache);
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free_percpu(dev->tstats);
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free_netdev(dev);
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}
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@ -462,7 +371,7 @@ ip6_tnl_dev_uninit(struct net_device *dev)
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RCU_INIT_POINTER(ip6n->tnls_wc[0], NULL);
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else
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ip6_tnl_unlink(ip6n, t);
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ip6_tnl_dst_reset(t);
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dst_cache_reset(&t->dst_cache);
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dev_put(dev);
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}
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@ -1069,7 +978,7 @@ static int ip6_tnl_xmit2(struct sk_buff *skb,
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memcpy(&fl6->daddr, addr6, sizeof(fl6->daddr));
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neigh_release(neigh);
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} else if (!fl6->flowi6_mark)
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dst = ip6_tnl_dst_get(t);
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dst = dst_cache_get(&t->dst_cache);
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if (!ip6_tnl_xmit_ctl(t, &fl6->saddr, &fl6->daddr))
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goto tx_err_link_failure;
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@ -1133,7 +1042,7 @@ static int ip6_tnl_xmit2(struct sk_buff *skb,
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}
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if (!fl6->flowi6_mark && ndst)
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ip6_tnl_dst_set(t, ndst);
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dst_cache_set_ip6(&t->dst_cache, ndst, &fl6->saddr);
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skb_dst_set(skb, dst);
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skb->transport_header = skb->network_header;
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@ -1366,7 +1275,7 @@ ip6_tnl_change(struct ip6_tnl *t, const struct __ip6_tnl_parm *p)
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t->parms.flowinfo = p->flowinfo;
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t->parms.link = p->link;
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t->parms.proto = p->proto;
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ip6_tnl_dst_reset(t);
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dst_cache_reset(&t->dst_cache);
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ip6_tnl_link_config(t);
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return 0;
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}
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@ -1637,7 +1546,7 @@ ip6_tnl_dev_init_gen(struct net_device *dev)
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if (!dev->tstats)
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return -ENOMEM;
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ret = ip6_tnl_dst_init(t);
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ret = dst_cache_init(&t->dst_cache, GFP_KERNEL);
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if (ret) {
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free_percpu(dev->tstats);
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dev->tstats = NULL;
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@ -640,7 +640,7 @@ vti6_tnl_change(struct ip6_tnl *t, const struct __ip6_tnl_parm *p)
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t->parms.i_key = p->i_key;
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t->parms.o_key = p->o_key;
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t->parms.proto = p->proto;
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ip6_tnl_dst_reset(t);
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dst_cache_reset(&t->dst_cache);
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vti6_link_config(t);
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return 0;
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}
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