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From: Wei Liu <wei.liu2@citrix.com>
To: David Vrabel <david.vrabel@citrix.com>
Cc: Wei Liu <liuw@liuw.name>, Ian Campbell <Ian.Campbell@citrix.com>,
	"konrad.wilk@oracle.com" <konrad.wilk@oracle.com>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>,
	"annie.li@oracle.com" <annie.li@oracle.com>
Subject: Re: [Xen-devel] [PATCH 5/6] xen-netback: coalesce slots before copying
Date: Tue, 26 Mar 2013 11:29:59 +0000	[thread overview]
Message-ID: <20130326112959.GF7004@zion.uk.xensource.com> (raw)
In-Reply-To: <515182E2.50103@citrix.com>

On Tue, Mar 26, 2013 at 11:13:38AM +0000, David Vrabel wrote:
> >>
> >> Separately, it may be sensible for the backend to drop packets with more
> >> frags than max-slots-per-frame up to some threshold where anything more
> >> is considered malicious (i.e., 1 - 18 slots is a valid packet, 19-20 are
> >> dropped and 21 or more is a fatal error).
> >>
> > 
> > Why drop the packet when we are able to process it? Frontend cannot know
> > it has crossed the line anyway.
> 
> Because it's a change to the protocol and we do not want to do this for
> a regression fix.
> 

If I understand correctly the regression you talked about was introduced
by harsh punishment in XSA-39? If so, this is the patch you need to fix
that. Frontend only knows that it has connectivity or not. This patch
guarantee that the old netfront with larger MAX_SKB_FRAGS still see the
same thing from its point of view.  Netfront cannot know the
intermediate state between 18 and 20.

> As a separate fix we can consider increasing the number of slots
> per-packet once there is a mechanism to report this to the front end.
> 

Sure, that's on my TODO list.


Wei.

  parent reply	other threads:[~2013-03-26 11:30 UTC|newest]

Thread overview: 106+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-03-25 11:08 [PATCH 0/6 V2] Bundle fixes for Xen netfront / netback Wei Liu
2013-03-25 11:08 ` [PATCH 1/6] xen-netfront: remove unused variable `extra' Wei Liu
2013-03-25 11:08 ` Wei Liu
2013-03-25 14:21   ` [Xen-devel] " David Vrabel
2013-03-25 14:21   ` David Vrabel
2013-03-25 16:20   ` David Miller
2013-03-25 16:20   ` David Miller
2013-03-25 11:08 ` [PATCH 2/6] xen-netfront: reduce gso_max_size to account for ethernet header Wei Liu
2013-03-25 11:08 ` Wei Liu
2013-03-25 13:54   ` Malcolm Crossley
2013-03-25 14:23   ` [Xen-devel] " David Vrabel
2013-03-25 14:39     ` Jan Beulich
2013-03-25 14:39     ` Jan Beulich
2013-03-25 14:23   ` David Vrabel
2013-03-25 15:50   ` Sergei Shtylyov
2013-03-25 15:50   ` Sergei Shtylyov
2013-03-25 16:18   ` David Miller
2013-03-25 16:54     ` Eric Dumazet
2013-03-25 16:54     ` Eric Dumazet
2013-03-25 16:59       ` David Miller
2013-03-25 17:24         ` Eric Dumazet
2013-03-25 17:24         ` Eric Dumazet
2013-03-25 20:49         ` Ben Hutchings
2013-03-25 20:49         ` Ben Hutchings
2013-03-25 16:59       ` David Miller
2013-03-25 18:32     ` Wei Liu
2013-03-25 18:32     ` Wei Liu
2013-03-25 18:39       ` David Miller
2013-03-25 18:39       ` David Miller
2013-03-25 19:09         ` Malcolm Crossley
2013-03-25 16:18   ` David Miller
2013-03-25 16:56   ` Konrad Rzeszutek Wilk
2013-03-25 16:56   ` Konrad Rzeszutek Wilk
2013-03-25 11:08 ` [PATCH 3/6] xen-netfront: frags -> slots in xennet_get_responses Wei Liu
2013-03-25 11:08 ` Wei Liu
2013-03-25 14:25   ` [Xen-devel] " David Vrabel
2013-03-25 14:25   ` David Vrabel
2013-03-25 16:20   ` David Miller
2013-03-25 16:20   ` David Miller
2013-03-25 11:08 ` [PATCH 4/6] xen-netback: remove skb in xen_netbk_alloc_page Wei Liu
2013-03-25 16:20   ` David Miller
2013-03-25 16:20   ` David Miller
2013-03-25 11:08 ` Wei Liu
2013-03-25 11:08 ` [PATCH 5/6] xen-netback: coalesce slots before copying Wei Liu
2013-03-25 11:08 ` Wei Liu
2013-03-25 15:13   ` David Vrabel
2013-03-25 15:47     ` [Xen-devel] " Wei Liu
2013-03-25 16:34       ` David Vrabel
2013-03-25 16:58         ` Wei Liu
2013-03-25 17:06           ` [Xen-devel] " Wei Liu
2013-03-25 17:06           ` Wei Liu
2013-03-25 18:29           ` [Xen-devel] " David Vrabel
2013-03-25 19:09             ` Wei Liu
2013-03-26  9:16               ` Paul Durrant
2013-03-26  9:16               ` [Xen-devel] " Paul Durrant
2013-03-26  9:51                 ` Wei Liu
2013-03-26  9:51                 ` [Xen-devel] " Wei Liu
2013-03-26 11:00                 ` James Harper
2013-03-26 11:24                   ` Paul Durrant
2013-03-26 11:29                     ` James Harper
2013-03-26 11:38                       ` Paul Durrant
2013-03-26 11:38                       ` [Xen-devel] " Paul Durrant
2013-03-26 11:29                     ` James Harper
2013-03-26 11:24                   ` Paul Durrant
2013-03-26 11:27                   ` David Laight
2013-03-26 11:27                   ` [Xen-devel] " David Laight
2013-03-26 11:00                 ` James Harper
2013-03-26 10:52               ` James Harper
2013-03-26 10:52               ` [Xen-devel] " James Harper
2013-03-26 11:06                 ` David Vrabel
2013-03-26 11:15                   ` James Harper
2013-03-26 11:15                   ` [Xen-devel] " James Harper
2013-03-26 11:06                 ` David Vrabel
2013-03-26 11:13               ` David Vrabel
2013-03-26 11:13               ` [Xen-devel] " David Vrabel
2013-03-26 11:29                 ` Wei Liu
2013-03-26 11:29                 ` Wei Liu [this message]
2013-03-25 19:09             ` Wei Liu
2013-03-25 18:29           ` David Vrabel
2013-03-25 16:34       ` David Vrabel
2013-03-25 15:47     ` Wei Liu
2013-03-25 15:13   ` David Vrabel
2013-03-25 16:20   ` David Miller
2013-03-25 16:20   ` David Miller
2013-03-25 16:57   ` [Xen-devel] " Konrad Rzeszutek Wilk
2013-04-09 15:10     ` Ian Campbell
2013-04-09 15:10     ` Ian Campbell
2013-03-25 16:57   ` Konrad Rzeszutek Wilk
2013-03-26 18:02   ` David Vrabel
2013-03-26 18:02   ` David Vrabel
2013-03-25 11:08 ` [PATCH 6/6] xen-netback: don't disconnect frontend when seeing oversize frame Wei Liu
2013-03-25 11:08 ` Wei Liu
2013-03-25 11:47   ` David Vrabel
2013-03-25 12:00     ` Wei Liu
2013-03-25 12:00     ` Wei Liu
2013-03-25 11:47   ` David Vrabel
2013-03-25 12:53   ` Jan Beulich
2013-03-25 12:53   ` [Xen-devel] " Jan Beulich
2013-03-25 13:52     ` Wei Liu
2013-03-25 13:52     ` [Xen-devel] " Wei Liu
2013-03-25 16:21   ` David Miller
2013-03-25 16:21   ` David Miller
2013-03-25 16:58   ` [Xen-devel] " Konrad Rzeszutek Wilk
2013-03-27 10:03     ` William Dauchy
2013-03-27 10:03     ` William Dauchy
2013-03-25 16:58   ` Konrad Rzeszutek Wilk

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