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tcp: annotate tp->snd_nxt lockless reads

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There are few places where we fetch tp->snd_nxt while
this field can change from IRQ or other cpu.

We need to add READ_ONCE() annotations, and also make
sure write sides use corresponding WRITE_ONCE() to avoid
store-tearing.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2019-10-10 20:17:42 -07:00 • committed by David S. Miller
parent 0f31746452
commit e0d694d638
4 changed files with 13 additions and 9 deletions
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3
net/ipv4/tcp.c
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@ -625,7 +625,8 @@ int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg)
if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
answ = 0;
else
answ = READ_ONCE(tp->write_seq) - tp->snd_nxt;
answ = READ_ONCE(tp->write_seq) -
READ_ONCE(tp->snd_nxt);
break;
default:
return -ENOIOCTLCMD;