Re: [REGRESSION, bisect]cxgb4 port failure with TSO traffic after commit 10d3be569243def8("tcp-tso: do not split TSO packets at retransmit time")

On Monday, June 06/27/16, 2016 at 19:06:05 +0530, Neal Cardwell wrote:

On Mon, Jun 27, 2016 at 9:27 AM, Eric Dumazet [off-list ref] wrote:

quoted

Excellent idea ;)

Here is the v2 patch.

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 8bd9911fdd16..e00e972c4e6a 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c

@@ -2751,7 +2751,7 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
        struct tcp_sock *tp = tcp_sk(sk);
        struct sk_buff *skb;
        struct sk_buff *hole = NULL;
-       u32 last_lost;
+       u32 max_segs, last_lost;
        int mib_idx;
        int fwd_rexmitting = 0;

@@ -2771,6 +2771,7 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
                last_lost = tp->snd_una;
        }

+       max_segs = tcp_tso_autosize(sk, tcp_current_mss(sk));
        tcp_for_write_queue_from(skb, sk) {
                __u8 sacked = TCP_SKB_CB(skb)->sacked;
                int segs;

@@ -2784,6 +2785,10 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
                segs = tp->snd_cwnd - tcp_packets_in_flight(tp);
                if (segs <= 0)
                        return;
+               /* In case tcp_shift_skb_data() have aggregated large skbs,
+                * we need to make sure not sending too big TSO packets.
+                */
+               segs = min_t(int, segs, max_segs);

                if (fwd_rexmitting) {
 begin_fwd:

Looks great to me. Thanks, Eric!

neal

This patch works fine. Now I am not seeing any packets with len > 64K. Thanks Eric for your support.

Arjun.