On Tue, Mar 16, 2021 at 10:50 AM Pavel Machek <pavel@xxxxxxx> wrote: > > Hi! > > > From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > > > > From: Eric Dumazet <edumazet@xxxxxxxxxx> > > Dup. > > > > We need to add READ_ONCE() annotations, and also make > > sure write sides use corresponding WRITE_ONCE() to avoid > > store-tearing. > > > @@ -1037,7 +1037,7 @@ new_segment: > > sk->sk_wmem_queued += copy; > > sk_mem_charge(sk, copy); > > skb->ip_summed = CHECKSUM_PARTIAL; > > - tp->write_seq += copy; > > + WRITE_ONCE(tp->write_seq, tp->write_seq + copy); > > TCP_SKB_CB(skb)->end_seq += copy; > > tcp_skb_pcount_set(skb, 0); > > > > I wonder if this needs to do READ_ONCE, too? No, because we hold the socket lock. This is a backport to ease another backport, please try to review patches when they hit mainline, if you have any concerns. > > > @@ -1391,7 +1391,7 @@ new_segment: > > if (!copied) > > TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_PSH; > > > > - tp->write_seq += copy; > > + WRITE_ONCE(tp->write_seq, tp->write_seq + copy); > > TCP_SKB_CB(skb)->end_seq += copy; > > tcp_skb_pcount_set(skb, 0); > > > > And here. > > > @@ -2593,9 +2594,12 @@ int tcp_disconnect(struct sock *sk, int > > sock_reset_flag(sk, SOCK_DONE); > > tp->srtt_us = 0; > > tp->rcv_rtt_last_tsecr = 0; > > - tp->write_seq += tp->max_window + 2; > > - if (tp->write_seq == 0) > > - tp->write_seq = 1; > > + > > + seq = tp->write_seq + tp->max_window + 2; > > + if (!seq) > > + seq = 1; > > + WRITE_ONCE(tp->write_seq, seq); > > And here. > > > --- a/net/ipv4/tcp_minisocks.c > > +++ b/net/ipv4/tcp_minisocks.c > > @@ -510,7 +510,7 @@ struct sock *tcp_create_openreq_child(co > > newtp->app_limited = ~0U; > > > > tcp_init_xmit_timers(newsk); > > - newtp->write_seq = newtp->pushed_seq = treq->snt_isn + 1; > > + WRITE_ONCE(newtp->write_seq, newtp->pushed_seq = treq->snt_isn + 1); > > Would it be better to do assignment to pushed_seq outside of > WRITE_ONCE macro? This is ... "interesting". > > Best regards, > Pavel > -- > DENX Software Engineering GmbH, Managing Director: Wolfgang Denk > HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
