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Message-Id: <20140825.172804.1112825546843491474.davem@davemloft.net>
Date: Mon, 25 Aug 2014 17:28:04 -0700 (PDT)
From: David Miller <davem@...emloft.net>
To: vyasevich@...il.com
Cc: netdev@...r.kernel.org, vyasevic@...hat.com,
jeffrey.t.kirsher@...el.com, jesse.brandeburg@...el.com,
bruce.w.allan@...el.com, carolyn.wyborny@...el.com,
donald.c.skidmore@...el.com, gregory.v.rose@...el.com,
alexander.h.duyck@...el.com, john.ronciak@...el.com,
mitch.a.williams@...el.com, linux.nics@...el.com,
e1000-devel@...ts.sourceforge.net, rmody@...cade.com,
cascardo@...ux.vnet.ibm.com, thomas.petazzoni@...e-electrons.com,
shahed.shaikh@...gic.com, jitendra.kalsaria@...gic.com,
ron.mercer@...gic.com, linux-driver@...gic.com, cmetcalf@...era.com
Subject: Re: [PATCH v2 0/8] Fix TSO and checksum issues with
non-accelerated vlan traffic.
From: Vladislav Yasevich <vyasevich@...il.com>
Date: Mon, 25 Aug 2014 10:34:47 -0400
> I've recently ran across something rather interesting when testing vlans
> from inside VMs. In some scenarios I was getting awfull thruput.
> Some debugging uncovered a very scary packet corruption. I was
> seeing packets that had original TSO length as IP total length
> and their ip checksum was 0. This was with e1000e driver.
>
> A bit more debugging uncovered an assumption made by that driver
> that skb->protocol will contain l3 protocol information. This
> was not the case in my setup since I manually turned off vlan
> tx acceleration for the device. This caused the driver to not
> initialize the tso information correctly and resulted in
> corrupt TSO frames on the wire.
>
> I decided to do some auditing of the usage of skb->protocols
> in the drivers. Out of all the drivers, the included 8 appear
> to be effected. They all allow user to control vlan acceleration
> settings, all support TSO on vlan devices, and all use
> skb->protocol to decide how to encode TSO information. Some
> also have similar problems when initializing hw checksum information.
> On such device, it is simple enough to reproduce the issue.
> Simply turn off TX VLAN acceleration on the device, create a vlan,
> and run you favorite network performance tool.
>
> There is 1 driver I ran across that I belive will trigger a BUG
> in the system when used with vlans. That driver is tile/tilepro.c
> I have not changed it in this patch set and would hope that
> the maintainer has time to look at it.
>
> V2: Fix i40ev using the wrong function name. Full build.
Applied, thanks.
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