Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [patch 15/36] Hexagon: Add init_task and process functions | Date | Wed, 17 Aug 2011 21:45:10 +0200 |
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On Wednesday 17 August 2011 11:35:12 Richard Kuo wrote: > +/* > + * Spin, or better still, do a hardware or VM wait instruction > + * If hardware or VM offer wait termination even though interrupts > + * are disabled. > + */ > +static void default_idle(void) > +{ > + __vmwait(); > +} > + > +void (*idle_sleep)(void) = default_idle; > + > +void cpu_idle(void) > +{ > + while (1) { > + tick_nohz_stop_sched_tick(1); > + while (!need_resched()) > + idle_sleep(); > + tick_nohz_restart_sched_tick(); > + schedule(); > + } > +}
This looks like you have the classic going to sleep race in here:
You need to disable hardware interrupts before checking need_resched(), otherwise an interrupt might hit just after you have checked it and before you call __vmwait(). The definition of the __vmwait call must atomically reenable interrupts and suspend the CPU.
Arnd
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