On Friday, February 06, 2015 07:29:22 PM Peter Zijlstra wrote: > On Fri, Feb 06, 2015 at 05:14:54PM +0100, Peter Zijlstra wrote: > > On Fri, Feb 06, 2015 at 02:20:13AM +0100, Rafael J. Wysocki wrote: > > > void freeze_wake(void) > > > { > > > + unsigned long flags; > > > + > > > + spin_lock_irqsave(&suspend_freeze_lock, flags); > > > + if (suspend_freeze_state > FREEZE_STATE_NONE) { > > > + suspend_freeze_state = FREEZE_STATE_WAKE; > > > + wake_up(&suspend_freeze_wait_head); > > > + } > > > + spin_unlock_irqrestore(&suspend_freeze_lock, flags); > > > } > > > > > > > +static void enter_freeze_proper(struct cpuidle_driver *drv, > > > + struct cpuidle_device *dev, int index) > > > +{ > > > + tick_freeze(); > > > + drv->states[index].enter_freeze(dev, drv, index); > > > + /* > > > + * timekeeping_resume() that will be called by tick_unfreeze() for the > > > + * last CPU executing it calls functions containing RCU read-side > > > + * critical sections, so tell RCU about that. > > > + */ > > > + RCU_NONIDLE(tick_unfreeze()); > > > +} > > > > So I'm a wee bit confused; if we use an enter_freeze() state that keeps > > interrupts disabled; who is going to call the freeze_wake() thing? > > Ah, I think I see, so we wake up, keep the interrupt pending, re-enable > the tick and time and everybody, then re-enable interrupts, take the > interrupt and go around the idle loop to find we need a reschedule etc..
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