From: Arvid Brodin <arvid.brodin@xdin.com>
To: David Miller <davem@davemloft.net>
Cc: Arvid Brodin <arvid.brodin@xdin.com>, <netdev@vger.kernel.org>,
<shemminger@vyatta.com>, <joe@perches.com>,
<jboticario@gmail.com>, <balferreira@googlemail.com>,
<elias.molina@ehu.es>
Subject: Re: [PATCH v4] net/hsr: Add support for the High-availability Seamless Redundancy protocol (HSRv0)
Date: Sat, 21 Sep 2013 03:28:29 +0200 [thread overview]
Message-ID: <523CF63D.7030505@xdin.com> (raw)
In-Reply-To: <523CF077.8010607@xdin.com>
On 2013-09-21 03:03, Arvid Brodin wrote:
> On 2013-09-21 02:43, Arvid Brodin wrote:
>> It's weird though, the "len" bug doesn't show up in my practical tests -
>> scp of 16 MiB file (sha1sum compared afterwards) and ping with default
>> and 65 KB packets work just fine before and after this change - even
>> between one fixed system and one with the bug remaining. Could it be
>> that none of the network device drivers we use (e1000e and macb) make
>> use of nonlinear skbs?
>
> Forget about this, e1000e is running on an architecture with
> HAVE_EFFICIENT_UNALIGNED_ACCESS, and on macb it does affect things -
> with the "fix" nothing works. :-|
... and that is because I have already shortened the packet through the
call to strip_hsr_tag() a few lines above, which calls
skb_pull(..., HSR_TAGLEN) in turn. So ->len is already correct.
Moving both ->data and ->tail, and all data between them, HSR_TAGLEN bytes
lower, should not be a problem if
a) the space ahead of ->data is vacant (not part of the packet),
b) there is enough headroom,
c) it does not break 32-bit alignment, and
d) there are no references to headers etc in the data being moved.
Right?
--
Arvid Brodin | Consultant (Linux)
XDIN AB | Knarrarnäsgatan 7 | SE-164 40 Kista | Sweden | xdin.com
next prev parent reply other threads:[~2013-09-21 1:28 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-19 1:11 [PATCH v4] net/hsr: Add support for the High-availability Seamless Redundancy protocol (HSRv0) Arvid Brodin
2013-09-20 19:10 ` David Miller
2013-09-21 0:43 ` Arvid Brodin
2013-09-21 1:03 ` Arvid Brodin
2013-09-21 1:28 ` Arvid Brodin [this message]
2013-09-30 15:09 ` Arvid Brodin
2013-10-15 19:59 ` Arvid Brodin
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