| Message ID | 1509651025.2849.23.camel@edumazet-glaptop3.roam.corp.google.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
| Series | [net] tcp: do not mangle skb->cb[] in tcp_make_synack() | expand |
On 02/11/17 - 12:30:25, Eric Dumazet wrote: > From: Eric Dumazet <edumazet@google.com> > > Christoph Paasch sent a patch to address the following issue : > > tcp_make_synack() is leaving some TCP private info in skb->cb[], > then send the packet by other means than tcp_transmit_skb() > > tcp_transmit_skb() makes sure to clear skb->cb[] to not confuse > IPv4/IPV6 stacks, but we have no such cleanup for SYNACK. > > tcp_make_synack() should not use tcp_init_nondata_skb() : > > tcp_init_nondata_skb() really should be limited to skbs put in write/rtx > queues (the ones that are only sent via tcp_transmit_skb()) > > This patch fixes the issue and should even save few cpu cycles ;) > > Fixes: 971f10eca186 ("tcp: better TCP_SKB_CB layout to reduce cache line misses") > Signed-off-by: Eric Dumazet <edumazet@google.com> > Reported-by: Christoph Paasch <cpaasch@apple.com> > --- > net/ipv4/tcp_output.c | 9 ++------- > 1 file changed, 2 insertions(+), 7 deletions(-) Reviewed-by: Christoph Paasch <cpaasch@apple.com>
From: Eric Dumazet <eric.dumazet@gmail.com> Date: Thu, 02 Nov 2017 12:30:25 -0700 > From: Eric Dumazet <edumazet@google.com> > > Christoph Paasch sent a patch to address the following issue : > > tcp_make_synack() is leaving some TCP private info in skb->cb[], > then send the packet by other means than tcp_transmit_skb() > > tcp_transmit_skb() makes sure to clear skb->cb[] to not confuse > IPv4/IPV6 stacks, but we have no such cleanup for SYNACK. > > tcp_make_synack() should not use tcp_init_nondata_skb() : > > tcp_init_nondata_skb() really should be limited to skbs put in write/rtx > queues (the ones that are only sent via tcp_transmit_skb()) > > This patch fixes the issue and should even save few cpu cycles ;) > > Fixes: 971f10eca186 ("tcp: better TCP_SKB_CB layout to reduce cache line misses") > Signed-off-by: Eric Dumazet <edumazet@google.com> > Reported-by: Christoph Paasch <cpaasch@apple.com> Applied and queued up for -stable.
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 823003eef3a21a5cc5c27e0be9f46159afa060df..478909f4694d00076c96b7a3be1eda62b6be8bef 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -3180,13 +3180,8 @@ struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, th->source = htons(ireq->ir_num); th->dest = ireq->ir_rmt_port; skb->mark = ireq->ir_mark; - /* Setting of flags are superfluous here for callers (and ECE is - * not even correctly set) - */ - tcp_init_nondata_skb(skb, tcp_rsk(req)->snt_isn, - TCPHDR_SYN | TCPHDR_ACK); - - th->seq = htonl(TCP_SKB_CB(skb)->seq); + skb->ip_summed = CHECKSUM_PARTIAL; + th->seq = htonl(tcp_rsk(req)->snt_isn); /* XXX data is queued and acked as is. No buffer/window check */ th->ack_seq = htonl(tcp_rsk(req)->rcv_nxt);