Re: [Lse-tech] Re: [Patch 2/7] Add sysctl for schedstats

Arjan van de Ven
2006-02-27T12:18:51Z

On Mon, 2006-02-27 at 16:16 +0530, Balbir Singh wrote:
> <snip>
> > why not just introduce a schedstats_lock mutex, and acquire it for both
> > the 'if (schedstats_sysctl)' line and the schedstats_set() line. That
> > will make the locking meaningful: two parallel sysctl ops will be atomic
> > to each other. [right now they wont be and they can clear schedstat data
> > in parallel -> not a big problem but it makes schedstats_lock rather
> > meaningless]
> >
>
> Ingo,
>
> Can sysctl's run in parallel? sys_sysctl() is protects the call
> to do_sysctl() with BKL (lock_kernel/unlock_kernel).
>
> Am I missing something?

your sysctl functions sleep. the BKL is useless in the light of sleeping
code...