Re: [PATCH net-next v7 RESEND] tcp: trace retransmit failures in tcp_retransmit_skb

[Eric Dumazet]

On Sun, Jul 20, 2025 at 8:16 PM <fan.yu9@xxxxxxxxxx> wrote:
>
> From: Fan Yu <fan.yu9@xxxxxxxxxx>
>
> Background
> ==========
> When TCP retransmits a packet due to missing ACKs, the
> retransmission may fail for various reasons (e.g., packets
> stuck in driver queues, receiver zero windows, or routing issues).
>
> The original tcp_retransmit_skb tracepoint:
>
>   'commit e086101b150a ("tcp: add a tracepoint for tcp retransmission")'
>
> lacks visibility into these failure causes, making production
> diagnostics difficult.
>
>

> Suggested-by: Jakub Kicinski <kuba@xxxxxxxxxx>
> Suggested-by: Eric Dumazet <edumazet@xxxxxxxxxx>
> Co-developed-by: xu xin <xu.xin16@xxxxxxxxxx>
> Signed-off-by: xu xin <xu.xin16@xxxxxxxxxx>
> Signed-off-by: Fan Yu <fan.yu9@xxxxxxxxxx>
> Reviewed-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>

Please do not add a Suggested-by tag when the original idea did not
come from someone else.

I only made suggestions to make your patch better.

Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>