diff options
| author | Eric Dumazet <edumazet@google.com> | 2023-09-12 16:02:11 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2023-09-15 10:33:48 +0100 |
| commit | 6b724bc4300b431443f3b99520994a5aece347cd (patch) | |
| tree | 02730c15dc86341705749df48ed87b7ca84688c1 /include | |
| parent | 83cd5eb654b320c1972254f243531f3f3cebcccf (diff) | |
| download | lwn-6b724bc4300b431443f3b99520994a5aece347cd.tar.gz lwn-6b724bc4300b431443f3b99520994a5aece347cd.zip | |
ipv6: lockless IPV6_MTU_DISCOVER implementation
Most np->pmtudisc reads are racy.
Move this 3bit field on a full byte, add annotations
and make IPV6_MTU_DISCOVER setsockopt() lockless.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/ipv6.h | 5 | ||||
| -rw-r--r-- | include/net/ip6_route.h | 14 |
2 files changed, 11 insertions, 8 deletions
diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h index f288a35f157f..10f521a6a9c8 100644 --- a/include/linux/ipv6.h +++ b/include/linux/ipv6.h @@ -243,13 +243,12 @@ struct ipv6_pinfo { } rxopt; /* sockopt flags */ - __u16 sndflow:1, - pmtudisc:3, - padding:1, /* 1 bit hole */ + __u8 sndflow:1, srcprefs:3; /* 001: prefer temporary address * 010: prefer public address * 100: prefer care-of address */ + __u8 pmtudisc; __u8 min_hopcount; __u8 tclass; __be32 rcv_flowinfo; diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h index b32539bb0fb0..b1ea49900b4a 100644 --- a/include/net/ip6_route.h +++ b/include/net/ip6_route.h @@ -266,7 +266,7 @@ static inline unsigned int ip6_skb_dst_mtu(const struct sk_buff *skb) const struct dst_entry *dst = skb_dst(skb); unsigned int mtu; - if (np && np->pmtudisc >= IPV6_PMTUDISC_PROBE) { + if (np && READ_ONCE(np->pmtudisc) >= IPV6_PMTUDISC_PROBE) { mtu = READ_ONCE(dst->dev->mtu); mtu -= lwtunnel_headroom(dst->lwtstate, mtu); } else { @@ -277,14 +277,18 @@ static inline unsigned int ip6_skb_dst_mtu(const struct sk_buff *skb) static inline bool ip6_sk_accept_pmtu(const struct sock *sk) { - return inet6_sk(sk)->pmtudisc != IPV6_PMTUDISC_INTERFACE && - inet6_sk(sk)->pmtudisc != IPV6_PMTUDISC_OMIT; + u8 pmtudisc = READ_ONCE(inet6_sk(sk)->pmtudisc); + + return pmtudisc != IPV6_PMTUDISC_INTERFACE && + pmtudisc != IPV6_PMTUDISC_OMIT; } static inline bool ip6_sk_ignore_df(const struct sock *sk) { - return inet6_sk(sk)->pmtudisc < IPV6_PMTUDISC_DO || - inet6_sk(sk)->pmtudisc == IPV6_PMTUDISC_OMIT; + u8 pmtudisc = READ_ONCE(inet6_sk(sk)->pmtudisc); + + return pmtudisc < IPV6_PMTUDISC_DO || + pmtudisc == IPV6_PMTUDISC_OMIT; } static inline const struct in6_addr *rt6_nexthop(const struct rt6_info *rt, |