Re: [PATCH net] tcp: make TCP_USER_TIMEOUT accurate for zero window probes

Hi, Jakub:

In terms of backporting, this patch should go together with:

    9d9b1ee0b2d1 tcp: fix TCP_USER_TIMEOUT with zero window

Thanks.  -- Enke

On Fri, Jan 22, 2021 at 05:43:25PM -0800, Jakub Kicinski wrote:

On Fri, 22 Jan 2021 11:13:06 -0800 Enke Chen wrote:

quoted

From: Enke Chen <redacted>

The TCP_USER_TIMEOUT is checked by the 0-window probe timer. As the
timer has backoff with a max interval of about two minutes, the
actual timeout for TCP_USER_TIMEOUT can be off by up to two minutes.

In this patch the TCP_USER_TIMEOUT is made more accurate by taking it
into account when computing the timer value for the 0-window probes.

This patch is similar to the one that made TCP_USER_TIMEOUT accurate for
RTOs in commit b701a99e431d ("tcp: Add tcp_clamp_rto_to_user_timeout()
helper to improve accuracy").

Signed-off-by: Enke Chen <redacted>
Reviewed-by: Neal Cardwell <ncardwell@google.com>

This is targeting net, any guidance on Fixes / backporting?