Re: [PATCH] tcp: keepalive fixes

[Eric Dumazet]

On Tue, Jan 12, 2021 at 11:48 PM Yuchung Cheng <ycheng@xxxxxxxxxx> wrote:
>
> On Tue, Jan 12, 2021 at 2:31 PM Enke Chen <enkechen2020@xxxxxxxxx> wrote:
> >
> > From: Enke Chen <enchen@xxxxxxxxxxxxxxxxxxxx>
> >
> > In this patch two issues with TCP keepalives are fixed:
> >
> > 1) TCP keepalive does not timeout when there are data waiting to be
> >    delivered and then the connection got broken. The TCP keepalive
> >    timeout is not evaluated in that condition.
> hi enke
> Do you have an example to demonstrate this issue -- in theory when
> there is data inflight, an RTO timer should be pending (which
> considers user-timeout setting). based on the user-timeout description
> (man tcp), the user timeout should abort the socket per the specified
> time after data commences. some data would help to understand the
> issue.
>

+1

A packetdrill test would be ideal.

Also, given that there is this ongoing issue with TCP_USER_TIMEOUT,
lets not mix things
or risk added work for backports to stable versions.