netdev.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
To: Jakub Kicinski <kuba@kernel.org>
Cc: Aleksandr Nogikh <a.nogikh@gmail.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	David Miller <davem@davemloft.net>,
	Johannes Berg <johannes@sipsolutions.net>,
	Eric Dumazet <edumazet@google.com>,
	Andrey Konovalov <andreyknvl@google.com>,
	Marco Elver <elver@google.com>,
	LKML <linux-kernel@vger.kernel.org>,
	netdev <netdev@vger.kernel.org>,
	linux-wireless <linux-wireless@vger.kernel.org>,
	Aleksandr Nogikh <nogikh@google.com>,
	Florian Westphal <fw@strlen.de>
Subject: Re: [PATCH 1/2] net: store KCOV remote handle in sk_buff
Date: Thu, 15 Oct 2020 15:04:11 -0400	[thread overview]
Message-ID: <CA+FuTSf2kfvdYydXYJNCCfE62q9DXXOBMh_ZSO5W=L9GK478HA@mail.gmail.com> (raw)
In-Reply-To: <20201013095038.61ba8f55@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>

On Tue, Oct 13, 2020 at 12:50 PM Jakub Kicinski <kuba@kernel.org> wrote:
>
> On Tue, 13 Oct 2020 18:59:28 +0300 Aleksandr Nogikh wrote:
> > On Mon, 12 Oct 2020 at 09:04, Dmitry Vyukov <dvyukov@google.com> wrote:
> > >
> > > On Sat, Oct 10, 2020 at 5:14 PM Jakub Kicinski <kuba@kernel.org> wrote:
> > > >
> > > > On Sat, 10 Oct 2020 09:54:57 +0200 Dmitry Vyukov wrote:
> > > > > On Sat, Oct 10, 2020 at 1:16 AM Jakub Kicinski <kuba@kernel.org> wrote:
> > [...]
> > > > > > Could you use skb_extensions for this?
> > > > >
> > > > > Why? If for space, this is already under a non-production ifdef.
> > > >
> > > > I understand, but the skb_ext infra is there for uncommon use cases
> > > > like this one. Any particular reason you don't want to use it?
> > > > The slight LoC increase?
> > > >
> > > > Is there any precedent for adding the kcov field to other performance
> > > > critical structures?
> >
> > It would be great to come to some conclusion on where exactly to store
> > kcov_handle. Technically, it is possible to use skb extensions for the
> > purpose, though it will indeed slightly increase the complexity.
> >
> > Jakub, you think that kcov_handle should be added as an skb extension,
> > right?
>
> That'd be preferable. I understand with current use cases it doesn't
> really matter, but history shows people come up with all sort of
> wonderful use cases down the line. And when they do they rarely go back
> and fix such fundamental minutiae.
>
> > Though I do not really object to moving the field, it still seems to
> > me that sk_buff itself is a better place. Right now skb extensions
> > store values that are local to specific protocols and that are only
> > meaningful in the context of these protocols (correct me if I'm
> > wrong). Although this patch only adds remote kcov coverage to the wifi
> > code, kcov_handle can be meaningful for other protocols as well - just
> > like the already existing sk_buff fields. So adding kcov_handle to skb
> > extensions will break this logical separation.
>
> It's not as much protocols as subsystems. The values are meaningful to
> a subsystem which inserts them, that doesn't mean single layer of the
> stack. If it was about storing layer's context we would just use
> skb->cb.
>
> So I think the kcov use matches pretty well.

skb_extensions was the first thing that came to mind when I read this
patchset too. It is not specific to protocols.

We have long stopped growing sk_buff size.

  reply	other threads:[~2020-10-15 19:04 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-07 10:17 [PATCH 0/2] net, mac80211: enable KCOV remote coverage collection for 802.11 frame handling Aleksandr Nogikh
2020-10-07 10:17 ` [PATCH 1/2] net: store KCOV remote handle in sk_buff Aleksandr Nogikh
2020-10-09 23:15   ` Jakub Kicinski
2020-10-10  7:54     ` Dmitry Vyukov
2020-10-10 15:14       ` Jakub Kicinski
2020-10-12  6:04         ` Dmitry Vyukov
2020-10-13 15:59           ` Aleksandr Nogikh
2020-10-13 16:50             ` Jakub Kicinski
2020-10-15 19:04               ` Willem de Bruijn [this message]
2020-10-16 14:20                 ` Aleksandr Nogikh
2020-10-12  7:12   ` Johannes Berg
2020-10-12 10:10     ` Aleksandr Nogikh
2020-10-07 10:17 ` [PATCH 2/2] mac80211: add KCOV remote annotations to incoming frame processing Aleksandr Nogikh
2020-10-07 11:48 ` [PATCH 0/2] net, mac80211: enable KCOV remote coverage collection for 802.11 frame handling Johannes Berg
2020-10-07 14:40   ` Aleksandr Nogikh

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='CA+FuTSf2kfvdYydXYJNCCfE62q9DXXOBMh_ZSO5W=L9GK478HA@mail.gmail.com' \
    --to=willemdebruijn.kernel@gmail.com \
    --cc=a.nogikh@gmail.com \
    --cc=andreyknvl@google.com \
    --cc=davem@davemloft.net \
    --cc=dvyukov@google.com \
    --cc=edumazet@google.com \
    --cc=elver@google.com \
    --cc=fw@strlen.de \
    --cc=johannes@sipsolutions.net \
    --cc=kuba@kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-wireless@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    --cc=nogikh@google.com \
    --subject='Re: [PATCH 1/2] net: store KCOV remote handle in sk_buff' \
    /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

This is a public inbox, see mirroring instructions
on how to clone and mirror all data and code used for this inbox