From: Eric Garver <e@erig.me>
To: Jiri Benc <jbenc@redhat.com>
Cc: netdev@vger.kernel.org, pravin shelar <pshelar@ovn.org>
Subject: Re: [PATCH net-next 1/2] openvswitch: remove nonreachable code in vlan parsing
Date: Tue, 4 Oct 2016 20:06:18 -0400 [thread overview]
Message-ID: <20161005000618.GN25403@egarver> (raw)
In-Reply-To: <cfc3e476bc30c1e15506e80955bf43563de3c16c.1475583870.git.jbenc@redhat.com>
Hi Jiri,
On Tue, Oct 04, 2016 at 02:30:01PM +0200, Jiri Benc wrote:
> It can never happen that there's a vlan tag in the packet but not in
> skb->vlan_tci. This is ensured in __netif_receive_skb_core and honored by
> skb_vlan_push and skb_vlan_pop. The code dealing with such case is a dead
> code.
>
This code is also called for packets passed back down from userspace
(after the flow key miss and upcall). So it does happen that we have a
skb without skb->vlan_tci set.
See the chain:
ovs_packet_cmd_execute()
ovs_flow_key_extract_userspace()
key_extract()
parse_vlan()
> Moreover, the likely() statement around skb_vlan_tag_present is bogus. This
> code is called whenever flow key is being extracted from the packet. The
> packet may be as likely vlan tagged as not.
>
I guess the unlikely scenario is the one I mention above.
next prev parent reply other threads:[~2016-10-05 0:06 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-04 12:30 [PATCH net-next 0/2] openvswitch: vlan fixes Jiri Benc
2016-10-04 12:30 ` [PATCH net-next 1/2] openvswitch: remove nonreachable code in vlan parsing Jiri Benc
2016-10-05 0:06 ` Eric Garver [this message]
2016-10-05 12:53 ` Jiri Benc
2016-10-04 12:30 ` [PATCH net-next 2/2] openvswitch: fix vlan subtraction from packet length Jiri Benc
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=20161005000618.GN25403@egarver \
--to=e@erig.me \
--cc=jbenc@redhat.com \
--cc=netdev@vger.kernel.org \
--cc=pshelar@ovn.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