Re: [PULL 00/32] VFIO updates 2020-10-26 (for QEMU 5.2 soft-freeze)

[Max Reitz]

On 28.10.20 09:11, Cornelia Huck wrote:
> On Tue, 27 Oct 2020 23:42:57 +0000
> Peter Maydell <peter.maydell@linaro.org> wrote:
> 
>> On Mon, 26 Oct 2020 at 19:39, Alex Williamson
>> <alex.williamson@redhat.com> wrote:
>>> ----------------------------------------------------------------
>>> VFIO update 2020-10-26
>>>
>>>  * Migration support (Kirti Wankhede)
>>>  * s390 DMA limiting (Matthew Rosato)
>>>  * zPCI hardware info (Matthew Rosato)
>>>  * Lock guard (Amey Narkhede)
>>>  * Print fixes (Zhengui li)  
>>
>> I get a conflict here in
>> include/standard-headers/linux/fuse.h:
>>
>> ++<<<<<<< HEAD
>>  +#define FUSE_ATTR_FLAGS               (1 << 27)
>> ++=======
>> + #define FUSE_SUBMOUNTS                (1 << 27)
>> ++>>>>>>> remotes/awilliam/tags/vfio-update-20201026.0  
>>
>> I assume these should not both be trying to use the same value,
>> so something has gone wrong somewhere. The conflicting commit
>> now in master is Max's 97d741cc96dd08 ("linux/fuse.h: Pull in from Linux").
>>
>> Can you sort out the correct resolution between you, please?
>> (My guess is that Max's commit is the erroneous one because
>> it doesn't look like it was created via a standard update
>> from the kernel headers.)
> 
> We should never change things in the synced headers other than via a
> headers update (excluding fixups of prior messes.) I'm pointing it out
> whenever I see something like that happening, but nobody is going to
> catch all of those.

Well, it was a kernel update.  Just based on a preliminary version of
the kernel part of the FUSE submount feature.

It was clear that the kernel part would have to be merged before the
qemu/virtiofsd series, and that did happen, but Miklos (the FUSE
maintainer) fixed some things on top while doing so, an that included
changing the flag in question.  As Adam wrote, I noted that I would thus
have to write a v2 of the virtiofsd series.

Unfortunately, that all was a bit buried in the thread, so I suppose for
Dave it looked like the kernel series was applied, so the virtiofsd
series could go in, too.  And I in turn didn't catch that. :/

> Is there any place where we can have some kind of automatic check on a
> pull request for that kind of stuff? We'd need to formalize an "update
> headers" commit message, or maybe have the update script write some
> kind of "last updated" file?
It would also need to actually check against the kernel tree, because,
well, I did use the script.  Just against a kernel tree that never came
to master.

Max