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ipv6: start using dst_dev_rcu() 

Refactor icmpv6_xrlim_allow() and ip6_dst_hoplimit()
so that we acquire rcu_read_lock() a bit longer
to be able to use dst_dev_rcu() instead of dst_dev().

__ip6_rt_update_pmtu() and rt6_do_redirect can directly
use dst_dev_rcu() in sections already holding rcu_read_lock().

Small changes to use dst_dev_net_rcu() in
ip6_default_advmss(), ipv6_sock_ac_join(),
ip6_mc_find_dev() and ndisc_send_skb().

Fixes: 4a6ce2b6f2 ("net: introduce a new function dst_dev_put()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/20250828195823.3958522-3-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2025-08-28 19:58:17 +00:00 committed by Jakub Kicinski
parent caedcc5b6d
commit b775ecf165
6 changed files with 14 additions and 13 deletions
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2
net/ipv6/anycast.c
View File

@ -104,7 +104,7 @@ int ipv6_sock_ac_join(struct sock *sk, int ifindex, const struct in6_addr *addr)
rcu_read_lock(); rcu_read_lock();
rt = rt6_lookup(net, addr, NULL, 0, NULL, 0); rt = rt6_lookup(net, addr, NULL, 0, NULL, 0);
if (rt) { if (rt) {
dev = dst_dev(&rt->dst); dev = dst_dev_rcu(&rt->dst);
netdev_hold(dev, &dev_tracker, GFP_ATOMIC); netdev_hold(dev, &dev_tracker, GFP_ATOMIC);
ip6_rt_put(rt); ip6_rt_put(rt);
} else if (ishost) { } else if (ishost) {

6
net/ipv6/icmp.c
View File

@ -209,7 +209,8 @@ static bool icmpv6_xrlim_allow(struct sock *sk, u8 type,
* this lookup should be more aggressive (not longer than timeout). * this lookup should be more aggressive (not longer than timeout).
*/ */
dst = ip6_route_output(net, sk, fl6); dst = ip6_route_output(net, sk, fl6);
dev = dst_dev(dst); rcu_read_lock();
dev = dst_dev_rcu(dst);
if (dst->error) { if (dst->error) {
IP6_INC_STATS(net, ip6_dst_idev(dst), IP6_INC_STATS(net, ip6_dst_idev(dst),
IPSTATS_MIB_OUTNOROUTES); IPSTATS_MIB_OUTNOROUTES);
@ -224,11 +225,10 @@ static bool icmpv6_xrlim_allow(struct sock *sk, u8 type,
if (rt->rt6i_dst.plen < 128) if (rt->rt6i_dst.plen < 128)
tmo >>= ((128 - rt->rt6i_dst.plen)>>5); tmo >>= ((128 - rt->rt6i_dst.plen)>>5);
rcu_read_lock();
peer = inet_getpeer_v6(net->ipv6.peers, &fl6->daddr); peer = inet_getpeer_v6(net->ipv6.peers, &fl6->daddr);
res = inet_peer_xrlim_allow(peer, tmo); res = inet_peer_xrlim_allow(peer, tmo);
rcu_read_unlock();
} }
rcu_read_unlock();
if (!res) if (!res)
__ICMP6_INC_STATS(net, ip6_dst_idev(dst), __ICMP6_INC_STATS(net, ip6_dst_idev(dst),
ICMP6_MIB_RATELIMITHOST); ICMP6_MIB_RATELIMITHOST);

2
net/ipv6/mcast.c
View File

@ -180,7 +180,7 @@ static struct net_device *ip6_mc_find_dev(struct net *net,
rcu_read_lock(); rcu_read_lock();
rt = rt6_lookup(net, group, NULL, 0, NULL, 0); rt = rt6_lookup(net, group, NULL, 0, NULL, 0);
if (rt) { if (rt) {
dev = dst_dev(&rt->dst); dev = dst_dev_rcu(&rt->dst);
dev_hold(dev); dev_hold(dev);
ip6_rt_put(rt); ip6_rt_put(rt);
} }

2
net/ipv6/ndisc.c
View File

@ -505,7 +505,7 @@ void ndisc_send_skb(struct sk_buff *skb, const struct in6_addr *daddr,
ip6_nd_hdr(skb, saddr, daddr, READ_ONCE(inet6_sk(sk)->hop_limit), skb->len); ip6_nd_hdr(skb, saddr, daddr, READ_ONCE(inet6_sk(sk)->hop_limit), skb->len);
dev = dst_dev(dst); dev = dst_dev_rcu(dst);
idev = __in6_dev_get(dev); idev = __in6_dev_get(dev);
IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTREQUESTS); IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTREQUESTS);

8
net/ipv6/output_core.c
View File

@ -104,18 +104,20 @@ EXPORT_SYMBOL(ip6_find_1stfragopt);
int ip6_dst_hoplimit(struct dst_entry *dst) int ip6_dst_hoplimit(struct dst_entry *dst)
{ {
int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT); int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);
rcu_read_lock();
if (hoplimit == 0) { if (hoplimit == 0) {
struct net_device *dev = dst_dev(dst); struct net_device *dev = dst_dev_rcu(dst);
struct inet6_dev *idev; struct inet6_dev *idev;
rcu_read_lock();
idev = __in6_dev_get(dev); idev = __in6_dev_get(dev);
if (idev) if (idev)
hoplimit = READ_ONCE(idev->cnf.hop_limit); hoplimit = READ_ONCE(idev->cnf.hop_limit);
else else
hoplimit = READ_ONCE(dev_net(dev)->ipv6.devconf_all->hop_limit); hoplimit = READ_ONCE(dev_net(dev)->ipv6.devconf_all->hop_limit);
rcu_read_unlock();
} }
rcu_read_unlock();
return hoplimit; return hoplimit;
} }
EXPORT_SYMBOL(ip6_dst_hoplimit); EXPORT_SYMBOL(ip6_dst_hoplimit);

7
net/ipv6/route.c
View File

@ -2943,7 +2943,7 @@ static void __ip6_rt_update_pmtu(struct dst_entry *dst, const struct sock *sk,
if (res.f6i->nh) { if (res.f6i->nh) {
struct fib6_nh_match_arg arg = { struct fib6_nh_match_arg arg = {
.dev = dst_dev(dst), .dev = dst_dev_rcu(dst),
.gw = &rt6->rt6i_gateway, .gw = &rt6->rt6i_gateway,
}; };
@ -3238,7 +3238,6 @@ EXPORT_SYMBOL_GPL(ip6_sk_redirect);
static unsigned int ip6_default_advmss(const struct dst_entry *dst) static unsigned int ip6_default_advmss(const struct dst_entry *dst)
{ {
struct net_device *dev = dst_dev(dst);
unsigned int mtu = dst_mtu(dst); unsigned int mtu = dst_mtu(dst);
struct net *net; struct net *net;
@ -3246,7 +3245,7 @@ static unsigned int ip6_default_advmss(const struct dst_entry *dst)
rcu_read_lock(); rcu_read_lock();
net = dev_net_rcu(dev); net = dst_dev_net_rcu(dst);
if (mtu < net->ipv6.sysctl.ip6_rt_min_advmss) if (mtu < net->ipv6.sysctl.ip6_rt_min_advmss)
mtu = net->ipv6.sysctl.ip6_rt_min_advmss; mtu = net->ipv6.sysctl.ip6_rt_min_advmss;
@ -4301,7 +4300,7 @@ static void rt6_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_bu
if (res.f6i->nh) { if (res.f6i->nh) {
struct fib6_nh_match_arg arg = { struct fib6_nh_match_arg arg = {
.dev = dst_dev(dst), .dev = dst_dev_rcu(dst),
.gw = &rt->rt6i_gateway, .gw = &rt->rt6i_gateway,
}; };