netdev.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Paolo Abeni <pabeni@redhat.com>
To: Ahmad Fatoum <a.fatoum@pengutronix.de>,
	netdev@vger.kernel.org, linux-can@vger.kernel.org,
	Pengutronix Kernel Team <kernel@pengutronix.de>
Subject: Re: [BUG] pfifo_fast may cause out-of-order CAN frame transmission
Date: Thu, 06 Feb 2020 14:21:16 +0100	[thread overview]
Message-ID: <13e8950e8537e549f6afb6e254ec75a7462ce648.camel@redhat.com> (raw)
In-Reply-To: <ef6b4e00-75fe-70f6-6b57-7bdbaa1aac33@pengutronix.de>

On Tue, 2020-02-04 at 17:25 +0100, Ahmad Fatoum wrote:
> Hello Paolo,
> 
> On 1/20/20 5:06 PM, Ahmad Fatoum wrote:
> > Hello Paolo,
> > 
> > On 1/16/20 1:40 PM, Paolo Abeni wrote:
> > > I'm sorry for this trial & error experience. I tried to reproduce the
> > > issue on top of the vcan virtual device, but it looks like it requires
> > > the timing imposed by a real device, and it's missing here (TL;DR: I
> > > can't reproduce the issue locally).
> > 
> > No worries. I don't mind testing.
> > 
> > > Code wise, the 2nd patch closed a possible race, but it dumbly re-
> > > opened the one addressed by the first attempt - the 'empty' field must
> > > be cleared prior to the trylock operation, or we may end-up with such
> > > field set and the queue not empty.
> > > 
> > > So, could you please try the following code?
> > 
> > Unfortunately, I still see observe reodering.
> 
> Any news?

I'm unable to find any better solution than a revert. That will cost
some small performace regression, so I'm a bit reluctant to go ahead.
If there is agreement I can post the revert.

Cheers,

Paolo


  reply	other threads:[~2020-02-06 13:21 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-08 14:55 [BUG] pfifo_fast may cause out-of-order CAN frame transmission Ahmad Fatoum
2020-01-09 12:51 ` Paolo Abeni
2020-01-09 17:39   ` Ahmad Fatoum
2020-01-10 16:31     ` Paolo Abeni
2020-01-12 21:29       ` Ahmad Fatoum
     [not found]         ` <57a2352dfc442ea2aa9cd653f8e09db277bf67c7.camel@redhat.com>
2020-01-20 16:06           ` Ahmad Fatoum
2020-02-04 16:25             ` Ahmad Fatoum
2020-02-06 13:21               ` Paolo Abeni [this message]
2020-02-06 17:06                 ` Oliver Hartkopp
2020-02-14 16:03                 ` Ahmad Fatoum
2020-10-07 21:07                 ` Vijayendra Suman

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=13e8950e8537e549f6afb6e254ec75a7462ce648.camel@redhat.com \
    --to=pabeni@redhat.com \
    --cc=a.fatoum@pengutronix.de \
    --cc=kernel@pengutronix.de \
    --cc=linux-can@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).