Hi Rafael, any opinion on this?
Thanks, Sören On Thu, 2014-10-02 at 09:01AM -0700, Sören Brinkmann wrote: > Hi Rafael, > > On Tue, 2014-09-23 at 01:01AM +0200, Rafael J. Wysocki wrote: > > On Monday, September 22, 2014 10:07:03 AM Soren Brinkmann wrote: > > > On platforms that do not power off during suspend, successfully entering > > > suspend races with timers. > > > > > > The race happening in a couple of location is: > > > > > > 1. disable IRQs (e.g. arch_suspend_disable_irqs()) > > > ... > > > 2. syscore_suspend() > > > -> timekeeping_suspend() > > > -> clockevents_notify(SUSPEND) > > > -> tick_suspend() (timers are turned off here) > > > ... > > > 3. wfi (wait for wake-IRQ here) > > > > > > Between steps 1 and 2 the timers can still generate interrupts that are > > > not handled and stay pending until step 3. That pending IRQ causes an > > > immediate - spurious - wake. > > > > > > The solution is to move the clockevents suspend/resume notification > > > out of the syscore_suspend step and explictly call them at the appropriate > > > time in the suspend/hibernation paths. I.e. timers are suspend _before_ > > > IRQs get disabled. And accordingly in the resume path. > > > > > > Signed-off-by: Soren Brinkmann <soren.brinkm...@xilinx.com> > > > --- > > > Hi, > > > > > > there was not a lot of discussion on the last submission. Just one > > > comment from > > > Rafael (https://lkml.org/lkml/2014/8/26/780), which - as I outlined in my > > > response, does not apply, IMHO, since the platform does not re-enable > > > interrupts. > > > > Well, you just don't agree with it. > > > > The problem with your approach is that timer interrupts aren't actually as > > special as you think and any other IRQF_NO_SUSPEND interrupts would have > > caused > > similar issues to appear under specific conditions. > > > > The solution I would suggest and that actually covers all IRQF_NO_SUSPEND > > interrupts would be to use a wait_event() loop like the one in > > freeze_enter() > > (on top of the current linux-next or the pm-genirq branch of linux-pm.git), > > but wait for pm_abort_suspend to become true, to implement system suspend. > > sorry, it took me a while since I needed to get some dependencies ported > to the pm-genirq base. Once I had that, it reproduced my original issue. > So far so good. I then looked into finding a solution following your > guidance. I'm not sure I really found what you had in mind, but below is > what I came up with, which seems to do it. > Please let me know how far off I am. > > Thanks, > Sören > > -------8<------------------8<----------------8<----------------8<--------------- > diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c > index c2744b30d5d9..a4f9914571f1 100644 > --- a/drivers/base/power/wakeup.c > +++ b/drivers/base/power/wakeup.c > @@ -25,7 +25,7 @@ > bool events_check_enabled __read_mostly; > > /* If set and the system is suspending, terminate the suspend. */ > -static bool pm_abort_suspend __read_mostly; > +bool pm_abort_suspend __read_mostly; > > /* > * Combined counters of registered wakeup events and wakeup events in > progress. > diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c > index 6dadb25cb0d8..e6a6de8f76d0 100644 > --- a/kernel/power/suspend.c > +++ b/kernel/power/suspend.c > @@ -33,6 +33,7 @@ > > static const char *pm_labels[] = { "mem", "standby", "freeze", }; > const char *pm_states[PM_SUSPEND_MAX]; > +extern bool pm_abort_suspend; > > static const struct platform_suspend_ops *suspend_ops; > static const struct platform_freeze_ops *freeze_ops; > @@ -294,25 +295,27 @@ static int suspend_enter(suspend_state_t state, bool > *wakeup) > if (error || suspend_test(TEST_CPUS)) > goto Enable_cpus; > > - arch_suspend_disable_irqs(); > - BUG_ON(!irqs_disabled()); > - > - error = syscore_suspend(); > - if (!error) { > - *wakeup = pm_wakeup_pending(); > - if (!(suspend_test(TEST_CORE) || *wakeup)) { > - trace_suspend_resume(TPS("machine_suspend"), > - state, true); > - error = suspend_ops->enter(state); > - trace_suspend_resume(TPS("machine_suspend"), > - state, false); > - events_check_enabled = false; > + while (!pm_abort_suspend) { > + arch_suspend_disable_irqs(); > + BUG_ON(!irqs_disabled()); > + > + error = syscore_suspend(); > + if (!error) { > + *wakeup = pm_wakeup_pending(); > + if (!(suspend_test(TEST_CORE) || *wakeup)) { > + trace_suspend_resume(TPS("machine_suspend"), > + state, true); > + error = suspend_ops->enter(state); > + trace_suspend_resume(TPS("machine_suspend"), > + state, false); > + events_check_enabled = false; > + } > + syscore_resume(); > } > - syscore_resume(); > - } > > - arch_suspend_enable_irqs(); > - BUG_ON(irqs_disabled()); > + arch_suspend_enable_irqs(); > + BUG_ON(irqs_disabled()); > + } > > Enable_cpus: > enable_nonboot_cpus(); > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/