All of lore.kernel.org
 help / color / mirror / Atom feed
From: Andrew Lunn <andrew@lunn.ch>
To: Alexander Lobakin <alobakin@dlink.ru>
Cc: "David S. Miller" <davem@davemloft.net>,
	Muciri Gatimu <muciri@openmesh.com>,
	Shashidhar Lakkavalli <shashidhar.lakkavalli@openmesh.com>,
	John Crispin <john@phrozen.org>,
	Vivien Didelot <vivien.didelot@gmail.com>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Stanislav Fomichev <sdf@google.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Song Liu <songliubraving@fb.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Matteo Croce <mcroce@redhat.com>,
	Jakub Sitnicki <jakub@cloudflare.com>,
	Eric Dumazet <edumazet@google.com>,
	Paul Blakey <paulb@mellanox.com>,
	Yoshiki Komachi <komachi.yoshiki@gmail.com>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH net] net: dsa: fix flow dissection on Tx path
Date: Thu, 5 Dec 2019 13:58:27 +0100	[thread overview]
Message-ID: <20191205125827.GA28269@lunn.ch> (raw)
In-Reply-To: <20191205100235.14195-1-alobakin@dlink.ru>

On Thu, Dec 05, 2019 at 01:02:35PM +0300, Alexander Lobakin wrote:
> Commit 43e665287f93 ("net-next: dsa: fix flow dissection") added an
> ability to override protocol and network offset during flow dissection
> for DSA-enabled devices (i.e. controllers shipped as switch CPU ports)
> in order to fix skb hashing for RPS on Rx path.
> 
> However, skb_hash() and added part of code can be invoked not only on
> Rx, but also on Tx path if we have a multi-queued device and:
>  - kernel is running on UP system or
>  - XPS is not configured.
> 
> The call stack in this two cases will be like: dev_queue_xmit() ->
> __dev_queue_xmit() -> netdev_core_pick_tx() -> netdev_pick_tx() ->
> skb_tx_hash() -> skb_get_hash().
> 
> The problem is that skbs queued for Tx have both network offset and
> correct protocol already set up even after inserting a CPU tag by DSA
> tagger, so calling tag_ops->flow_dissect() on this path actually only
> breaks flow dissection and hashing.

Hi Alexander

What i'm missing here is an explanation why the flow dissector is
called here if the protocol is already set? It suggests there is a
case when the protocol is not correctly set, and we do need to look
into the frame?

     Andrew

  reply	other threads:[~2019-12-05 12:58 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-05 10:02 [PATCH net] net: dsa: fix flow dissection on Tx path Alexander Lobakin
2019-12-05 12:58 ` Andrew Lunn [this message]
2019-12-05 13:34   ` Alexander Lobakin
2019-12-05 14:01     ` Andrew Lunn
2019-12-05 14:58       ` Alexander Lobakin
2019-12-06  3:32         ` Florian Fainelli
2019-12-06  7:37           ` Alexander Lobakin
2019-12-06 18:05             ` Florian Fainelli
2019-12-06  3:28 ` Florian Fainelli
2019-12-06 15:06   ` Alexander Lobakin
2019-12-06 19:32 ` Rainer Sickinger
2019-12-07  4:19 ` David Miller
2019-12-07  8:10   ` Alexander Lobakin

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=20191205125827.GA28269@lunn.ch \
    --to=andrew@lunn.ch \
    --cc=alobakin@dlink.ru \
    --cc=ast@kernel.org \
    --cc=daniel@iogearbox.net \
    --cc=davem@davemloft.net \
    --cc=edumazet@google.com \
    --cc=f.fainelli@gmail.com \
    --cc=jakub@cloudflare.com \
    --cc=john@phrozen.org \
    --cc=komachi.yoshiki@gmail.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mcroce@redhat.com \
    --cc=muciri@openmesh.com \
    --cc=netdev@vger.kernel.org \
    --cc=paulb@mellanox.com \
    --cc=sdf@google.com \
    --cc=shashidhar.lakkavalli@openmesh.com \
    --cc=songliubraving@fb.com \
    --cc=vivien.didelot@gmail.com \
    /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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.