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| author | Eric Dumazet <edumazet@google.com> | 2019-11-05 14:11:51 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2019-11-06 16:14:48 -0800 |
| commit | 25c7a6d1f90e208ec27ca854b1381ed39842ec57 (patch) | |
| tree | a645c406ef309589a1c6f851ca1ba761575a00b4 | |
| parent | 3828a93f5cfdf5d8a4ff9dead741e9a2871ff57b (diff) | |
| download | linux-25c7a6d1f90e208ec27ca854b1381ed39842ec57.tar.gz linux-25c7a6d1f90e208ec27ca854b1381ed39842ec57.tar.bz2 linux-25c7a6d1f90e208ec27ca854b1381ed39842ec57.zip | |
net: avoid potential false sharing in neighbor related code
There are common instances of the following construct :
if (n->confirmed != now)
n->confirmed = now;
A C compiler could legally remove the conditional.
Use READ_ONCE()/WRITE_ONCE() to avoid this problem.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | include/net/arp.h | 4 | ||||
| -rw-r--r-- | include/net/ndisc.h | 8 | ||||
| -rw-r--r-- | include/net/sock.h | 12 |
3 files changed, 12 insertions, 12 deletions
diff --git a/include/net/arp.h b/include/net/arp.h index c8f580a0e6b1..4950191f6b2b 100644 --- a/include/net/arp.h +++ b/include/net/arp.h @@ -57,8 +57,8 @@ static inline void __ipv4_confirm_neigh(struct net_device *dev, u32 key) unsigned long now = jiffies; /* avoid dirtying neighbour */ - if (n->confirmed != now) - n->confirmed = now; + if (READ_ONCE(n->confirmed) != now) + WRITE_ONCE(n->confirmed, now); } rcu_read_unlock_bh(); } diff --git a/include/net/ndisc.h b/include/net/ndisc.h index b2f715ca0567..b5ebeb3b0de0 100644 --- a/include/net/ndisc.h +++ b/include/net/ndisc.h @@ -414,8 +414,8 @@ static inline void __ipv6_confirm_neigh(struct net_device *dev, unsigned long now = jiffies; /* avoid dirtying neighbour */ - if (n->confirmed != now) - n->confirmed = now; + if (READ_ONCE(n->confirmed) != now) + WRITE_ONCE(n->confirmed, now); } rcu_read_unlock_bh(); } @@ -431,8 +431,8 @@ static inline void __ipv6_confirm_neigh_stub(struct net_device *dev, unsigned long now = jiffies; /* avoid dirtying neighbour */ - if (n->confirmed != now) - n->confirmed = now; + if (READ_ONCE(n->confirmed) != now) + WRITE_ONCE(n->confirmed, now); } rcu_read_unlock_bh(); } diff --git a/include/net/sock.h b/include/net/sock.h index ac6042d0af32..f2f853439b65 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1939,8 +1939,8 @@ struct dst_entry *sk_dst_check(struct sock *sk, u32 cookie); static inline void sk_dst_confirm(struct sock *sk) { - if (!sk->sk_dst_pending_confirm) - sk->sk_dst_pending_confirm = 1; + if (!READ_ONCE(sk->sk_dst_pending_confirm)) + WRITE_ONCE(sk->sk_dst_pending_confirm, 1); } static inline void sock_confirm_neigh(struct sk_buff *skb, struct neighbour *n) @@ -1950,10 +1950,10 @@ static inline void sock_confirm_neigh(struct sk_buff *skb, struct neighbour *n) unsigned long now = jiffies; /* avoid dirtying neighbour */ - if (n->confirmed != now) - n->confirmed = now; - if (sk && sk->sk_dst_pending_confirm) - sk->sk_dst_pending_confirm = 0; + if (READ_ONCE(n->confirmed) != now) + WRITE_ONCE(n->confirmed, now); + if (sk && READ_ONCE(sk->sk_dst_pending_confirm)) + WRITE_ONCE(sk->sk_dst_pending_confirm, 0); } } |