netdev - Re: [PATCH] e1000e: Cleanup handling of VLAN

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Message-ID: <1428537696.2729.4.camel@jtkirshe-mobl>
Date:	Wed, 08 Apr 2015 17:01:36 -0700
From:	Jeff Kirsher <jeffrey.t.kirsher@...el.com>
To:	Alexander Duyck <alexander.h.duyck@...hat.com>,
	Aaron Brown <aaron.f.brown@...el.com>
Cc:	intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
	mike@...tml.com, htodd@...fifty.com
Subject: Re: [PATCH] e1000e: Cleanup handling of VLAN_HLEN as a part of max
 frame size

On Wed, 2015-04-08 at 14:02 -0700, Alexander Duyck wrote:
> When the VLAN_HLEN was added to the calculation for the maximum frame
> size
> there seems to have been a number of issues added to the driver.
> 
> The first issue is that in some cases the maximum frame size for a
> device
> never really reached the actual maximum frame size as the VLAN header
> length was not included the calculation for that value.  As a result
> some
> parts only supported a maximum frame size of either 1496 in the case
> of
> parts that didn't support jumbo frames, and 8996 in the case of the
> parts
> that do.
> 
> The second issue is the fact that there were several checks that
> weren't
> updated so as a result setting an MTU of 1500 was treated as enabling
> jumbo
> frames as the calculated value was 1522 instead of 1518.  I have
> addressed
> those by replacing ETH_FRAME_LEN with VLAN_ETH_FRAME_LEN where
> appropriate.
> 
> The final issue was the fact that lowering the MTU below 1500 would
> cause
> the driver to allocate 2K buffers for the rings.  This is an old issue
> that
> was fixed several years ago in igb/ixgbe and I am addressing now by
> just
> replacing == with a <= so that we always just round up to 1522 for
> anything
> that isn't a jumbo frame.
> 
> Fixes: c751a3d58cf2d ("e1000e: Correctly include VLAN_HLEN when
> changing interface MTU")
> Signed-off-by: Alexander Duyck <alexander.h.duyck@...hat.com>
> ---
> 
> I have only build tested this though I am 99% sure the fixes here are
> correct.  This patch should fix issues on 82573 and ich8 w/ setting an
> MTU
> of 1500, and for the PCH series w/ setting an MTU of 9000.
> 
> I assume I can get away with bumping the max_hw_frame_size for the PCH
> parts from 9018 to 9022 based on the fact that the Windows INF for the
> parts
> lists supporting either 1514, 4088, and 9014 all of which exclude the
> 8
> bytes for CRC and VLAN header.
> 
>  drivers/net/ethernet/intel/e1000e/82571.c   |    2 +-
>  drivers/net/ethernet/intel/e1000e/ich8lan.c |   10 +++++-----
>  drivers/net/ethernet/intel/e1000e/netdev.c  |   18 ++++++++----------
>  3 files changed, 14 insertions(+), 16 deletions(-)

I have applied your patch to my queue, thanks Alex.
-- 
git://git.kernel.org/pub/scm/linux/kernel/git/jkirsher/next-queue.git
dev-queue

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