Messages in this thread Patch in this message | | | Date | Thu, 2 Oct 2014 09:01:15 -0700 | From | Sören Brinkmann <> | Subject | Re: [PATCH RESEND] PM / sleep: Fix racing timers |
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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.brinkmann@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 majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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