netdev - Re: [PATCH net-next] tcp: fix tcp_ofo_queue() to avoid including too much DUP SACK range

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Message-ID: <CAMaK5_jGfjpw5nqi2Z-a_nHNTvjj=KAvwSw=bO=FhbgzBpXHUA@mail.gmail.com>
Date: Tue, 24 Jun 2025 23:00:53 +0800
From: Xin Guo <guoxin0309@...il.com>
To: Jakub Kicinski <kuba@...nel.org>
Cc: ncardwell@...gle.com, netdev@...r.kernel.org
Subject: Re: [PATCH net-next] tcp: fix tcp_ofo_queue() to avoid including too
 much DUP SACK range

Thanks Jakub,  I will add more info and resend.

Regards
Guo Xin.
On Tue, Jun 24, 2025 at 2:57 AM Jakub Kicinski <kuba@...nel.org> wrote:
>
> On Tue, 17 Jun 2025 23:37:06 +0800 xin.guo wrote:
> > If the new coming segment covers more than one skbs in the ofo queue,
> > and which seq is equal to rcv_nxt , then the sequence range
> > that is not duplicated will be sent as DUP SACK,  the detail as below,
> > in step6, the {501,2001} range is clearly including too much
> > DUP SACK range:
> > 1. client.43629 > server.8080: Flags [.], seq 501:1001, ack 1325288529,
> > win 20000, length 500: HTTP
> > 2. server.8080 > client.43629: Flags [.], ack 1, win 65535, options
> > [nop,nop,TS val 269383721 ecr 200,nop,nop,sack 1 {501:1001}], length 0
> > 3. Iclient.43629 > server.8080: Flags [.], seq 1501:2001,
> > ack 1325288529, win 20000, length 500: HTTP
> > 4. server.8080 > client.43629: Flags [.], ack 1, win 65535, options
> > [nop,nop,TS val 269383721 ecr 200,nop,nop,sack 2 {1501:2001}
> > {501:1001}], length 0
> > 5. client.43629 > server.8080: Flags [.], seq 1:2001,
> > ack 1325288529, win 20000, length 2000: HTTP
> > 6. server.8080 > client.43629: Flags [.], ack 2001, win 65535,
> > options [nop,nop,TS val 269383722 ecr 200,nop,nop,sack 1 {501:2001}],
> > length 0
>
> Looks reasonable, AFAICT, tho perhaps there's some implicit benefit from
> reporting end of the DSACK == rcv_next..
>
> Could you please add the info about how the packet from step 6 looks
> "after" this patch? So we have before / after comparison?
>
> With that please resend and make sure you include _all_ maintainers that
> the get_maintainer script points out. You missed CCing Eric D.
> --
> pw-bot: cr