Subject: Re: [PATCH v3 1/2] vhost-net: fix handle_rx buffer size

From: Basil Gor <[email-masked]>
Date: Thu, 3 May 2012 18:43:26 +0400

On Thu, May 03, 2012 at 04:16:24PM +0300, Michael S. Tsirkin wrote:
> On Wed, Apr 25, 2012 at 09:01:15PM +0400, Basil Gor wrote:
> > Take vlan header length into account, when vlan id is stored as
> > vlan_tci. Otherwise tagged packets comming from macvtap will be
> > truncated.
> > 
> > Signed-off-by: Basil Gor <[email-masked]>
> 
> So I'm inclined to apply these two patches, we
> this doesn't fix packet socket backend
> but could be fixed by a follow-up patch.
> 

That's what I'm going to do.

While testing packet socket I noticed that tcpdump doesn't work
on macvtap0, since there is no dev_hard_start_xmit like in
tun/tap0 case I think (lines 120-144 in trace attached). And I
have no clear picture how to fix this gracefully.

Also I think there are issues with macvtap on top of bonding, that
I'm also going to verify and debug.

> > ---
> >  drivers/vhost/net.c |    7 ++++++-
> >  1 files changed, 6 insertions(+), 1 deletions(-)
> > 
> > diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
> > index 1f21d2a..5c17010 100644
> > --- a/drivers/vhost/net.c
> > +++ b/drivers/vhost/net.c
> > @@ -24,6 +24,7 @@
> >  #include <linux/if_arp.h>
> >  #include <linux/if_tun.h>
> >  #include <linux/if_macvlan.h>
> > +#include <linux/if_vlan.h>
> >  
> >  #include <net/sock.h>
> >  
> > @@ -283,8 +284,12 @@ static int peek_head_len(struct sock *sk)
> >  
> >  	spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
> >  	head = skb_peek(&sk->sk_receive_queue);
> > -	if (likely(head))
> > +	if (likely(head)) {
> >  		len = head->len;
> > +		if (vlan_tx_tag_present(head))
> > +			len += VLAN_HLEN;
> > +	}
> > +
> >  	spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
> >  	return len;
> >  }
> > -- 
> > 1.7.6.5
> > 
> > --
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