Re: [PATCH] PM / OPP: cpufreq: Avoid sleeping while atomic

[Viresh Kumar]

On 18 July 2014 04:57, Stephen Boyd <sboyd@xxxxxxxxxxxxxx> wrote:
> First you need to enable sleeping while atomic checking, but in reality,
> I assume nobody has tried inserting a cpufreq driver as a module. The

I did for sure, but long back. Over 6 months atleast :)

> might_sleep() code has a check to see if the system_state is
> SYSTEM_RUNNING. If it isn't running then there isn't a warning and
> might_sleep() doesn't flag any problem. I wonder if that is actually the
> right thing to do though? Perhaps the intention of that code is to skip
> warning early on in the boot path when the scheduler isn't up and
> running yet. But once the scheduler is running (which is fairly early
> nowadays) I would think we want might_sleep() to trigger warnings. Maybe
> that check in might_sleep() needs to be updated to check for "scheduler
> running" instead of "system running"?
> Right. It seems that we moved to RCU in commit
> 0f5c890e9b9754d9aa5bf6ae2fc00cae65780d23 so the real Fixes line should be:
>
> Fixes: 0f5c890e9b97 "PM / OPP: Remove cpufreq wrapper dependency on
> internal data organization"

Right.

> One way to avoid this problem is to put things back the way they were
> before that change. Is there any real benefit to having this code live
> in drivers/cpufreq/ instead of just under some config option in
> drivers/base/power/opp.c?

Maybe Nishanth can give more arguments than I can :), but the idea was
just to keep cpufreq stuff together..
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/