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From: "Michael S. Tsirkin" <mst@redhat.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Ben Hutchings <bhutchings@solarflare.com>,
	xiaohui.xin@intel.com, netdev@vger.kernel.org,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org, mingo@elte.hu,
	davem@davemloft.net, herbert@gondor.hengli.com.au,
	jdike@linux.intel.com, Sridhar Samudrala <sri@us.ibm.com>
Subject: Re: [PATCH v11 13/17] Add mp(mediate passthru) device.
Date: Tue, 28 Sep 2010 16:43:11 +0200	[thread overview]
Message-ID: <20100928144311.GB15294@redhat.com> (raw)
In-Reply-To: <201009281639.59417.arnd@arndb.de>

On Tue, Sep 28, 2010 at 04:39:59PM +0200, Arnd Bergmann wrote:
> On Tuesday 28 September 2010, Michael S. Tsirkin wrote:
> > > > +   skb_reserve(skb, NET_IP_ALIGN);
> > > > +   skb_put(skb, len);
> > > > +
> > > > +   if (skb_copy_datagram_from_iovec(skb, 0, iov, 0, len)) {
> > > > +           kfree_skb(skb);
> > > > +           return -EAGAIN;
> > > > +   }
> > > > +
> > > > +   skb->protocol = eth_type_trans(skb, mp->dev);
> > > 
> > > Why are you calling eth_type_trans() on transmit?
> > 
> > So that GSO can work.  BTW macvtap does:
> > 
> >         skb_set_network_header(skb, ETH_HLEN);
> >         skb_reset_mac_header(skb);
> >         skb->protocol = eth_hdr(skb)->h_proto;
> > 
> > and I think this is broken for vlans. Arnd?
> 
> Hmm, that code (besides set_network_header) was added by Sridhar
> for GSO support. I believe I originally did eth_type_trans but
> had to change it before that time because it broke something.
> Unfortunately, my memory on that is not very good any more.
> 
> Can you be more specific what the problem is? Do you think
> it breaks when a guest sends VLAN tagged frames or when macvtap
> is connected to a VLAN interface that adds another tag (or
> only the combination)?
> 
> 	Arnd

I expect the protocol value to be wrong when guest sends vlan tagged
frames as 802.1q frames have a different format.

-- 
MST

  reply	other threads:[~2010-09-28 14:49 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-09-25  4:27 [PATCH v11 00/17] Provide a zero-copy method on KVM virtio-net xiaohui.xin
2010-09-25  4:27 ` [PATCH v11 01/17] Add a new structure for skb buffer from external xiaohui.xin
2010-09-25  4:27   ` [PATCH v11 02/17] Add a new struct for device to manipulate external buffer xiaohui.xin
2010-09-27 13:41     ` Ben Hutchings
2010-09-25  4:27   ` [PATCH v11 03/17] Add a ndo_mp_port_prep pointer to net_device_ops xiaohui.xin
2010-09-27 13:42     ` Ben Hutchings
2010-09-29 13:41       ` Xin, Xiaohui
2010-09-25  4:27   ` [PATCH v11 04/17]Add a function make external buffer owner to query capability xiaohui.xin
2010-09-27 13:45     ` Ben Hutchings
2010-09-25  4:27   ` [PATCH v11 05/17] Add a function to indicate if device use external buffer xiaohui.xin
2010-09-25  4:27   ` [PATCH v11 06/17]Use callback to deal with skb_release_data() specially xiaohui.xin
2010-09-25  4:27   ` [PATCH v11 07/17] Modify netdev_alloc_page() to get external buffer xiaohui.xin
2010-09-25  4:27   ` [PATCH v11 08/17] Modify netdev_free_page() to release " xiaohui.xin
2010-09-25  4:27   ` [PATCH v11 09/17] Don't do skb recycle, if device use " xiaohui.xin
2010-09-25  4:27   ` [PATCH v11 10/17] Add a hook to intercept external buffers from NIC driver xiaohui.xin
2010-09-25  4:27   ` [PATCH v11 11/17] Add header file for mp device xiaohui.xin
2010-09-27 13:55     ` Ben Hutchings
2010-09-25  4:27   ` [PATCH v11 12/17] Add a kconfig entry and make entry " xiaohui.xin
2010-09-27 13:56     ` Ben Hutchings
2010-09-29 13:39       ` Xin, Xiaohui
2010-09-25  4:27   ` [PATCH v11 13/17] Add mp(mediate passthru) device xiaohui.xin
2010-09-27 21:23     ` Ben Hutchings
2010-09-28 13:06       ` Michael S. Tsirkin
2010-09-28 14:39         ` Arnd Bergmann
2010-09-28 14:43           ` Michael S. Tsirkin [this message]
2010-09-28 15:18             ` Arnd Bergmann
2010-09-28 18:48               ` Sridhar Samudrala
2010-09-29 13:38       ` Xin, Xiaohui
2010-09-25  4:27   ` [PATCH v11 14/17]Provides multiple submits and asynchronous notifications xiaohui.xin
2010-09-25  4:27   ` [PATCH v11 15/17]An example how to modifiy NIC driver to use napi_gro_frags() interface xiaohui.xin
2010-09-25  4:27   ` [PATCH v11 16/17]An example how to alloc user buffer based on " xiaohui.xin
2010-09-25  4:27   ` [PATCH v11 17/17]add two new ioctls for mp device xiaohui.xin
2010-09-27 21:36     ` Ben Hutchings
2010-09-28 13:09       ` Michael S. Tsirkin
2010-09-28  9:48     ` Michael S. Tsirkin
2010-09-29  9:36       ` xiaohui.xin
2010-09-26 17:01 ` [PATCH v11 00/17] Provide a zero-copy method on KVM virtio-net Michael S. Tsirkin
2010-09-27  0:44   ` Xin, Xiaohui
2010-09-28  1:25     ` Xin, Xiaohui

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