xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

net: avoid potential false sharing in neighbor related code

Browse Source 
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>
This commit is contained in:
Eric Dumazet
2019-11-05 14:11:51 -08:00
committed by David S. Miller
parent 3828a93f5c
commit 25c7a6d1f9
3 changed files with 12 additions and 12 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
include/net/sock.h
View File

@@ -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);
}
}