Re: [linux-nics] [PATCH net 3/5] fm10k: Implement ndo_gso_check()

On Thu, Nov 06, 2014 at 11:58:32PM +0000, Vick, Matthew wrote:

On 11/5/14, 11:36 AM, "Jeff Kirsher" [off-list ref] wrote:

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On Wed, 2014-11-05 at 10:26 -0800, Joe Stringer wrote:

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On 5 November 2014 04:47, Jeff Kirsher [off-list ref]
wrote:

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On Wed, 2014-11-05 at 14:44 +0200, Or Gerlitz wrote:

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On Wed, Nov 5, 2014 at 2:34 PM, Jeff Kirsher
[off-list ref] wrote:

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On Tue, 2014-11-04 at 13:56 -0800, Joe Stringer wrote:

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ndo_gso_check() was recently introduced to allow NICs to report

the

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offloading support that they have on a per-skb basis. Add an
implementation for this driver which checks for something that

looks

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like VXLAN.

Implementation shamelessly stolen from Tom Herbert:
http://thread.gmane.org/gmane.linux.network/332428/focus=333111

Signed-off-by: Joe Stringer <redacted>
---
Should this driver report support for GSO on packets with tunnel
headers
up to 64B like the i40e driver does?
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 drivers/net/ethernet/intel/fm10k/fm10k_netdev.c |   12

++++++++++++

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 1 file changed, 12 insertions(+)

Thanks Joe, I will add your patch to my queue.

Hi Jeff, please see my comment on patch 0/5, we're essentially
replicating the same helper four different times (fm10k, mlx4,

benet,

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qlgc) - I don't see the point in doing so. I asked Joe to come up

with

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one generic helper and then to pick it up by the four drivers, makes
sense?

Yeah, I just saw your reply Or.  Ok, I will await an update to Joe's
series, thanks!

Thanks Or/Jeff.

There is also the question in the commit message above, perhaps fm10k
support is a bit different - wasn't sure who to ask regarding that.

Matthew Vick is the fm10k maintainer now and can answer any fm10k
questions you may have.

Hi Joe, fm10k's hardware is pretty lax about the header size. As long as
the total header length (outer+inner) is 184 bytes or less we're golden,
so if I'm not mistaken that leaves us with a max of 130 bytes beyond the
tunnel header.

Oh, okay. To be more explicit, in the case of UDP tunnels I take it that
you're talking about L2+L3+(L4+)tunnel+L2+L3+L4 <= 184? (L4 perhaps
optional depending on the tunnel protocol used)

In that case, the fm10k_gso_check would use something closer to
"skb_inner_transport_header(skb) - skb_mac_header(skb) > 184", or
perhaps 164 to allow for inner L4 header (?).

Joe