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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
include/net/tcp.h
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@@ -1917,7 +1917,8 @@ static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
static inline bool tcp_stream_memory_free(const struct sock *sk, int wake)
{
const struct tcp_sock *tp = tcp_sk(sk);
u32 notsent_bytes = READ_ONCE(tp->write_seq) - tp->snd_nxt;
u32 notsent_bytes = READ_ONCE(tp->write_seq) -
READ_ONCE(tp->snd_nxt);
return (notsent_bytes << wake) < tcp_notsent_lowat(tp);
}