MIME-Version: 1.0
In-Reply-To: <CA+mtBx87o1Lo2zpMyUGC_P+7+DmXnZyA2NF0-GYCEWiRh6VJQg@mail.gmail.com>
References: <CAJ3xEMhxabp1EKbFPfvoZEFt=CQKFNcNrURGMX=7miDwmK9Y-A@mail.gmail.com>
 <20141105.163825.1433973842938441546.davem@davemloft.net> <20141106010501.GA18339@gmail.com>
 <20141105.211558.969082848816106943.davem@davemloft.net> <CA+mtBx-Js62X3BpfjQkcsh=w=-cgvSyM5ueCpufGVv0uu1nphw@mail.gmail.com>
 <CF9D1877D81D214CB0CA0669EFAE020C68CC79EF@CMEXMB1.ad.emulex.com> <CA+mtBx87o1Lo2zpMyUGC_P+7+DmXnZyA2NF0-GYCEWiRh6VJQg@mail.gmail.com>
From: Jesse Gross <jesse@nicira.com>
Date: Thu, 6 Nov 2014 08:15:46 -0800
Message-ID: <CAEP_g=_59JW8a0DRT8XcCAbDCnY1mzX8-bNcuVUL+sa8WBAHow@mail.gmail.com>
Subject: Re: [PATCH net 0/5] Implement ndo_gso_check() for vxlan nics
To: Tom Herbert <therbert@google.com>
Cc: Sathya Perla <Sathya.Perla@emulex.com>, David Miller <davem@davemloft.net>,
        Joe Stringer <joestringer@nicira.com>,
        Or Gerlitz <gerlitz.or@gmail.com>,
        Linux Netdev List <netdev@vger.kernel.org>,
        Jeff Kirsher <jeffrey.t.kirsher@intel.com>,
        Amir Vadai <amirv@mellanox.com>,
        "shahed.shaikh" <shahed.shaikh@qlogic.com>,
        dept-gelinuxnicdev <Dept-GELinuxNICDev@qlogic.com>,
        LKML <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset=UTF-8
Sender: linux-kernel-owner@vger.kernel.org

On Thu, Nov 6, 2014 at 8:06 AM, Tom Herbert <therbert@google.com> wrote:
> On Wed, Nov 5, 2014 at 10:16 PM, Sathya Perla <Sathya.Perla@emulex.com> wrote:
>>> -----Original Message-----
>>> From: Tom Herbert [mailto:therbert@google.com]
>>>
>>> On Wed, Nov 5, 2014 at 6:15 PM, David Miller <davem@davemloft.net>
>>> wrote:
>>> > From: Joe Stringer <joestringer@nicira.com>
>>> > Date: Wed, 5 Nov 2014 17:06:46 -0800
>>> >
>>> >> My impression was that the changes are more likely to be
>>> >> hardware-specific (like the i40e changes) rather than software-specific,
>>> >> like changes that might be integrated into the helper.
>>> >
>>> > I think there is more commonality amongst hardware capabilities,
>>> > and this is why I want the helper to play itself out.
>>> >
>>> >> That said, I can rework for one helper. The way I see it would be the
>>> >> same code as these patches, as "vxlan_gso_check(struct sk_buff *)" in
>>> >> drivers/net/vxlan.c which would be called from each driver. Is that what
>>> >> you had in mind?
>>> >
>>> > Yes.
>>>
>>> Note that this code is not VXLAN specific, it will also accept NVGRE
>>> and GRE/UDP with keyid and TEB. I imagine all these cases should be
>>> indistinguishable to the hardware so they probably just work (which
>>> would be cool!). It might be better to name and locate the helper
>>> function to reflect that.
>>
>> Tom, I'm confused as to how the value of (skb_inner_mac_header(skb) - skb_transport_header(skb))
>> would be the same for VxLAN and NVGRE encapsulated packets. Wouldn't this value be 16 for VxLAN
>> and 8 for NVGRE?
>>
> The inner headers are reset in iptunnel_handle_offloads. This is
> called in the xmit encapsulation functions (GRE, fou, VXLAN, etc.)
> before adding in encapsulation headers (skb_push), so the
> mac_inner_header will point to the encapsulation payload, i.e. the
> encapsulated packet. This should not change after being set, although
> inner network and inner transport can. The headers are only set on the
> first encapsulation, so with nested tunnels the inner headers point to
> the innermost encapsulated packet. Since VXLAN and NVGRE have same
> size of encapsulation (8 UDP + 8 header),   skb_inner_mac_header(skb)
> - skb_transport_header(skb) should always be 16.

Tom, NVGRE is not encapsulated in UDP and it is not 16 bytes.

http://tools.ietf.org/html/draft-sridharan-virtualization-nvgre-06
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/