Re: [PATCH net-next v5 4/9] xen-netback: Change RX path for mapped SKB fragments

[Zoltan Kiss]

On 27/02/14 12:43, Wei Liu wrote:
> On Mon, Feb 24, 2014 at 03:08:31PM +0000, Zoltan Kiss wrote:
> > On 24/02/14 13:49, Zoltan Kiss wrote:
> > > On 22/02/14 23:18, Zoltan Kiss wrote:
> > > > On 18/02/14 17:45, Ian Campbell wrote:
> > > > > On Mon, 2014-01-20 at 21:24 +0000, Zoltan Kiss wrote:
> > > > >
> > > > > Re the Subject: change how? Perhaps "handle foreign mapped pages on the
> > > > > guest RX path" would be clearer.
> > > > Ok, I'll do that.
> > > >
> > > > > > RX path need to know if the SKB fragments are stored on
> > > > > > pages from another
> > > > > > domain.
> > > > > Does this not need to be done either before the mapping change
> > > > > or at the
> > > > > same time? -- otherwise you have a window of a couple of commits where
> > > > > things are broken, breaking bisectability.
> > > > I can move this to the beginning, to keep bisectability. I've
> > > > put it here originally because none of these makes sense without
> > > > the previous patches.
> > > Well, I gave it a close look: to move this to the beginning as a
> > > separate patch I would need to put move a lot of definitions from
> > > the first patch to here (ubuf_to_vif helper,
> > > xenvif_zerocopy_callback etc.). That would be the best from bisect
> > > point of view, but from patch review point of view even worse than
> > > now. So the only option I see is to merge this with the first 2
> > > patches, so it will be even bigger.
> > Actually I was stupid, we can move this patch earlier and introduce
> > stubs for those 2 functions. But for the another two patches (#6 and
> > #8) it's still true that we can't move them before, only merge them
> > into the main, as they heavily rely on the main patch. #6 is
> > necessary for Windows frontends, as they are keen to send too many
> > slots. #8 is quite a rare case, happens only if a guest wedge or
> > malicious, and sits on the packet.
> > So my question is still up: do you prefer perfect bisectability or
> > more segmented patches which are not that pain to review?
>
> What's the diff stat if you merge those patches?

 drivers/net/xen-netback/common.h    |   33 ++-
 drivers/net/xen-netback/interface.c |   67 +++++-
 drivers/net/xen-netback/netback.c   |  424 
++++++++++++++++++++++-------------
 3 files changed, 362 insertions(+), 162 deletions(-)

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