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authorEric Dumazet <edumazet@google.com>2019-11-06 01:11:51 +0300
committerDavid S. Miller <davem@davemloft.net>2019-11-07 03:14:48 +0300
commit25c7a6d1f90e208ec27ca854b1381ed39842ec57 (patch)
treea645c406ef309589a1c6f851ca1ba761575a00b4
parent3828a93f5cfdf5d8a4ff9dead741e9a2871ff57b (diff)
downloadlinux-25c7a6d1f90e208ec27ca854b1381ed39842ec57.tar.xz
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.h4
-rw-r--r--include/net/ndisc.h8
-rw-r--r--include/net/sock.h12
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);
}
}