[Xen-devel] Re: netback commit history

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 20.09.11 at 14:40, Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx> wrote:
> On Tue, 2011-09-20 at 12:46 +0100, Jan Beulich wrote:
>> >>> On 20.09.11 at 13:26, Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx> wrote:
>> > On Tue, 2011-09-20 at 12:04 +0100, Jan Beulich wrote:
>> >> with the upstream netback introduction consisting of a single big commit
>> >> I wonder whether you could point me to where the full history of it is.
>> > 
>> > Yeah, that was a bit annoying, luckily I had the foresight to post where
>> > the history was. http://www.gossamer-threads.com/lists/xen/devel/202139 
>> > says it is:
>> >         git://xenbits.xen.org/people/ianc/linux-2.6.git 
>> > upstream/dom0/backend/netback-history 
>> 
>> Does this have a http:// representation somewhere (it doesn't show up
>> under http://xenbits.xen.org/people/ianc/)? 
> 
> http://xenbits.xen.org/gitweb/?p=people/ianc/linux-2.6.git;a=summary 
> 
>> 
>> >> I'm asking particularly in the context of us being asked to add a safety
>> >> check similar to the vif->netbk != NULL one at the beginning of
>> >> xenvif_start_xmit() (also in xenvif_interrupt(), but there we have a
>> >> similar check in place), which hadn't been in the legacy tree (obviously)
>> >> nor in the original multiple-tasklets patch that I retained a copy of.
>> > 
>> > Seems to have come from bc05ada1283eb583c9789c27429af36b034c4a74 in that
>> > history tree and was a conversion from a check for group == -1. That
>> > commit changes from storing a group index to a group pointer so I think
>> > it's roughly equivalent from a validity point of view.
>> > 
>> > The original group == -1 check appears to be in the 2.6.32.x pvops
>> > kernels at least, I expect it is also in the multiple tasklet patch
>> > which you have as well?
>> 
>> That's the point - we don't.
> 
> Wierd, it is in 020ba9067e121b720a3335521698ea9cf31f6166 in Jeremy's
> xen/2.6.32-stable branch which is the original "xen/netback: Multiple
> tasklets support." commit. Did you pick up an earlier posting?
> 
> I found the original postings
> v2: http://lists.xensource.com/archives/html/xen-devel/2010-04/msg01578.html 
> v3: http://www.gossamer-threads.com/lists/xen/devel/170582 
> v4: http://lists.xensource.com/archives/html/xen-devel/2010-05/msg00140.html 
> 
> From the looks things the check arrived in v3 but there is no comment on
> the patch saying why, nor does any review I found of v2 give a hint. I
> had a bit of a trawl through various list archives of the other postings
> of the series but didn't spot anything.

Seems like my original is actually v1, and I may not have picked up
that later change precisely because it wasn't mentioned in the
description and I didn't look closely enough at the changes plus I
had done quite a bit of other cleanup on v1 already and hence
didn't want to start over. v3 is also where the similar check in
netif_be_int() appears, and I know for sure we had to add this
due to another bug report, not due to the change there.

In any case, thanks a lot for helping with this!

Jan


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