On Tue, Mar 16, 2021 at 10:50 AM Pavel Machek pavel@denx.de wrote:
Hi!
From: Greg Kroah-Hartman gregkh@linuxfoundation.org
From: Eric Dumazet edumazet@google.com
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