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From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
To: Richard Sanger <rsanger@wand.net.nz>
Cc: Network Development <netdev@vger.kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>
Subject: Re: [PATCH] net: packetmmap: fix only tx timestamp on request
Date: Mon, 3 May 2021 20:36:31 -0400	[thread overview]
Message-ID: <CA+FuTSeDTYMZzT3n3tfm9KPCRx_ObWU-HaU4JxZCSCm_8sf2XA@mail.gmail.com> (raw)
In-Reply-To: <1620085579-5646-1-git-send-email-rsanger@wand.net.nz>

On Mon, May 3, 2021 at 8:04 PM Richard Sanger <rsanger@wand.net.nz> wrote:
>
> The packetmmap tx ring should only return timestamps if requested,
> as documented. This allows compatibility with non-timestamp aware
> user-space code which checks tp_status == TP_STATUS_AVAILABLE;
> not expecting additional timestamp flags to be set.

This is an established interface.

Passing the status goes back to 2013, since commit b9c32fb27170
("packet: if hw/sw ts enabled in rx/tx ring, report which ts we got").

Passing a timestamp itself in tp_sec/tp_usec goes back to before git,
probably to the introduction of the ring.

I don't think we can change this now. That will likely break
applications that have come to expect current behavior.

Is it documented somewhere that the ring works differently? Or are you
referring to the general SO_TIMESTAMPING behavior, which is a separate
timestamp interface.

  reply	other threads:[~2021-05-04  0:37 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-03 23:46 [PATCH] net: packetmmap: fix only tx timestamp on request Richard Sanger
2021-05-04  0:36 ` Willem de Bruijn [this message]
2021-05-04  1:22   ` Richard Sanger
2021-05-04 14:45     ` Willem de Bruijn
2021-05-05  4:29       ` Richard Sanger
2021-05-05  5:09         ` Richard Sanger
2021-05-06  1:23         ` Willem de Bruijn
2021-05-11 22:11           ` Richard Sanger
2021-05-11 22:56             ` Willem de Bruijn

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