Nouveau - Feb 2018 - [PATCH 0/5] Fix deadlock on runtime suspend in DRM drivers

On 2018-02-14 03:08 PM, Sean Paul wrote:
> On Wed, Feb 14, 2018 at 10:26:35AM +0100, Maarten Lankhorst wrote:
>> Op 14-02-18 om 09:46 schreef Lukas Wunner:
>>> Dear drm-misc maintainers,
>>>
>>> On Sun, Feb 11, 2018 at 10:38:28AM +0100, Lukas Wunner wrote:
>>>> Fix a deadlock on hybrid graphics laptops that's been
present since 2013:
>>> This series has been reviewed, consent has been expressed by the
most
>>> interested parties, patch [1/5] which touches files outside
drivers/gpu
>>> has been acked and I've just out a v2 addressing the only
objection
>>> raised.  My plan is thus to wait another two days for comments and,
>>> barring further objections, push to drm-misc this weekend.
>>>
>>> However I'm struggling with the decision whether to push to
next or
>>> fixes.  The series is marked for stable, however the number of
>>> affected machines is limited and for an issue that's been
present
>>> for 5 years it probably doesn't matter if it soaks another two
months
>>> in linux-next befor it gets backported.  Hence I tend to err on the
>>> side of caution and push to next, however a case could be made that
>>> fixes is more appropriate.
>>>
>>> I'm lacking experience making such decisions and would be
interested
>>> to learn how you'd handle this.
>>>
>>> Thanks,
>>>
>>> Lukas
>>
>> I would say fixes, it doesn't look particularly scary. :)
> 
> Agreed. If it's good enough for stable, it's good enough for
-fixes!
It's not that simple, is it? Fast-tracking patches (some of which appear
to be untested) to stable without an immediate cause for urgency seems
risky to me.


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer

On Wed, Feb 14, 2018 at 03:43:56PM +0100, Michel Dänzer
wrote:
> On 2018-02-14 03:08 PM, Sean Paul wrote:
> > On Wed, Feb 14, 2018 at 10:26:35AM +0100, Maarten Lankhorst wrote:
> >> Op 14-02-18 om 09:46 schreef Lukas Wunner:
> >>> Dear drm-misc maintainers,
> >>>
> >>> On Sun, Feb 11, 2018 at 10:38:28AM +0100, Lukas Wunner wrote:
> >>>> Fix a deadlock on hybrid graphics laptops that's been
present since 2013:
> >>> This series has been reviewed, consent has been expressed by
the most
> >>> interested parties, patch [1/5] which touches files outside
drivers/gpu
> >>> has been acked and I've just out a v2 addressing the only
objection
> >>> raised.  My plan is thus to wait another two days for comments
and,
> >>> barring further objections, push to drm-misc this weekend.
> >>>
> >>> However I'm struggling with the decision whether to push
to next or
> >>> fixes.  The series is marked for stable, however the number of
> >>> affected machines is limited and for an issue that's been
present
> >>> for 5 years it probably doesn't matter if it soaks another
two months
> >>> in linux-next befor it gets backported.  Hence I tend to err
on the
> >>> side of caution and push to next, however a case could be made
that
> >>> fixes is more appropriate.
> >>>
> >>> I'm lacking experience making such decisions and would be
interested
> >>> to learn how you'd handle this.
> >>>
> >>> Thanks,
> >>>
> >>> Lukas
> >>
> >> I would say fixes, it doesn't look particularly scary. :)
> > 
> > Agreed. If it's good enough for stable, it's good enough for
-fixes!
> 
> It's not that simple, is it? Fast-tracking patches (some of which
appear
> to be untested) to stable without an immediate cause for urgency seems
> risky to me.
> 
/me should be more careful what he says

Given where we are in the release cycle, it's barely a fast track. If these
go
in -fixes, they'll get in -rc2 and will have plenty of time to bake. If we
were
at rc5, it might be a different story.

Sean
> 
> -- 
> Earthling Michel Dänzer               |               http://www.amd.com
> Libre software enthusiast             |             Mesa and X developer
-- 
Sean Paul, Software Engineer, Google / Chromium OS

On Wed, Feb 14, 2018 at 09:58:43AM -0500, Sean Paul
wrote:
> On Wed, Feb 14, 2018 at 03:43:56PM +0100, Michel Dänzer wrote:
> > On 2018-02-14 03:08 PM, Sean Paul wrote:
> > > On Wed, Feb 14, 2018 at 10:26:35AM +0100, Maarten Lankhorst
wrote:
> > >> Op 14-02-18 om 09:46 schreef Lukas Wunner:
> > >>> On Sun, Feb 11, 2018 at 10:38:28AM +0100, Lukas Wunner
wrote:
> > >>>> Fix a deadlock on hybrid graphics laptops that's
been present since 2013:
> > >>> This series has been reviewed, consent has been expressed
by the most
> > >>> interested parties, patch [1/5] which touches files
outside drivers/gpu
> > >>> has been acked and I've just out a v2 addressing the
only objection
> > >>> raised.  My plan is thus to wait another two days for
comments and,
> > >>> barring further objections, push to drm-misc this
weekend.
> > >>>
> > >>> However I'm struggling with the decision whether to
push to next or
> > >>> fixes.  The series is marked for stable, however the
number of
> > >>> affected machines is limited and for an issue that's
been present
> > >>> for 5 years it probably doesn't matter if it soaks
another two months
> > >>> in linux-next befor it gets backported.  Hence I tend to
err on the
> > >>> side of caution and push to next, however a case could be
made that
> > >>> fixes is more appropriate.
> > >>>
> > >>> I'm lacking experience making such decisions and
would be interested
> > >>> to learn how you'd handle this.
> > >>
> > >> I would say fixes, it doesn't look particularly scary. :)
> > > 
> > > Agreed. If it's good enough for stable, it's good enough
for -fixes!
> > 
> > It's not that simple, is it? Fast-tracking patches (some of which
appear
> > to be untested) to stable without an immediate cause for urgency seems
> > risky to me.
> 
> /me should be more careful what he says
> 
> Given where we are in the release cycle, it's barely a fast track.
> If these go in -fixes, they'll get in -rc2 and will have plenty of
> time to bake. If we were at rc5, it might be a different story.
The patches are marked for stable though, so if they go in through
drm-misc-fixes, they may appear in stable kernels before 4.16-final
is out.  Greg picks up patches once they're in Linus' tree, though
often with a delay of a few days or weeks.  If they go in through
drm-misc-next, they're guaranteed not to appear in *any* release
before 4.16-final is out.

This allows for differentiation between no-brainer stable fixes that
can be sent immediately and scarier, but similarly important stable
fixes that should soak for a while.  I'm not sure which category
this series belongs to, though it's true what Maarten says, it's
not *that* grave a change.

Thanks,

Lukas