On Fri, 24 Jul 2020 at 15:17, Aaron Lu <aaron....@gmail.com> wrote: > > On Wed, Jul 22, 2020 at 12:23:44AM +0000, benbjiang(蒋彪) wrote: > > > > > > > +/* > > > + * This function takes care of adjusting the min_vruntime of siblings of > > > + * a core during coresched enable/disable. > > > + * This is called in stop machine context so no need to take the rq lock. > > Hi, > > > > IMHO, it seems that stop machine context cannot guarantee race free. The > > param *cpu* maybe not *this_cpu*, rq lock should be taken even in stop > > machine context, and irq should be disabled too, to avoid potential races > > with other contexts. > > > > In stop machine context, all CPUs except the active ones are spinning > with irq disabled and in this invocation of stop_machine(), only one > CPU is active so I don't think race is possible. You're right, stop_machine provides much more protection than stop_*_cpu. Thanks for the explanation.
Regards, Jiang
