Re: [Intel-gfx] [PATCH 0/5] Fix deadlock on runtime suspend in DRM drivers

Daniel Vetter
2018-02-19T11:48:04Z

On Thu, Feb 15, 2018 at 06:38:44AM +0100, Lukas Wunner wrote:
> 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.

If you're this concerned about them, then pls do _not_ put cc: stable on
the patches. Instead get them merged through -fixes (or maybe even -next),
and once they're sufficiently tested, send a mail to stable@ asking for
ane explicit backport.

Stuff that's marked for stable must be obviuos and tested enough for
backporting right away (which doesn't seem to be the case here).
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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