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

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
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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