Re: [PATCH v2] firmware: fix sending -ERESTARTSYS due to signal on fallback

[Dmitry Torokhov]

On Fri, May 26, 2017 at 02:32:31PM -0700, Luis R. Rodriguez wrote:
> On Fri, May 26, 2017 at 2:26 PM, Dmitry Torokhov
> <dmitry.torokhov@xxxxxxxxx> wrote:
> > On Fri, May 26, 2017 at 12:46 PM, Luis R. Rodriguez <mcgrof@xxxxxxxxxx> wrote:
> >> On Fri, May 26, 2017 at 06:09:29AM -0500, Eric W. Biederman wrote:
> >>> "Fuzzey, Martin" <mfuzzey@xxxxxxxxxxx> writes:
> >>> >>>> Maybe SIGCHLD shouldn't interrupt firmware loading?
> >>> >
> >>> > I don't think there's a way of doing that without disabling all
> >>> > signals (ie using the non interruptible wait variants).
> >>> > It used to be that way (which is why I only ran into this after
> >>> > updating from an ancient 3.16 kernel to a slightly less ancient 4.4)
> >>> > But there are valid reasons for wanting to be able to interrupt
> >>> > firmware loading (like being able to kill the userspace helper)
> >>>
> >>> Perhaps simply using a killable wait and not a fully interruptible
> >>> wait would be better?
> >>
> >> What do you mean by a killable wait BTW?
> >
> > https://lwn.net/Articles/288056/
> >
> > I think only interrupting firmware loading with fatal signals would
> > make a lot of sense.
> >
> >>
> >> ret = swait_event_interruptible_timeout() is being used right now.
> >
> > It looks like we are missing swait_event_killable*(), but I do not
> > think it would be hard to add.
> 
> What should we do for stable ? Is this a *stable* issue ?

I think it is, as you have users complaining about behavior. I do not
think we need to make their lives harder than needed by requiring
handling signals.

I do not see why we could not introduce wait_event_killable_timeout()
and swait_event_killable_timeout() into -stables.

Thanks.

-- 
Dmitry