netdev - Re: [PATCH net-next] vrf: Add ethernet header for pass through VRF device

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-Id: <20150826.173058.1864374511836166828.davem@davemloft.net>
Date:	Wed, 26 Aug 2015 17:30:58 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	dsa@...ulusnetworks.com
Cc:	netdev@...r.kernel.org, shm@...ulusnetworks.com
Subject: Re: [PATCH net-next] vrf: Add ethernet header for pass through VRF
 device

From: David Ahern <dsa@...ulusnetworks.com>
Date: Wed, 26 Aug 2015 12:36:15 -0700

> As such all we need is to push an eth header to the front of the skb
> for 1 loop through the stack and eth_header via dev_hard_header with
> NULL daddr is the simplest path to accomplish that. Any other path is
> just extra overhead.

And dev_hard_header() is full of conditional code and partial stores,
whereas the hard header cache is a _SINGLE UNCONDITIONAL MEMCPY_.

You're making this data path more expensive than it needs to be just
to placate features which in no way are default situations.

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html