On Sun, Apr 21, 2013 at 11:42:41PM +0200, Borislav Petkov wrote:
> On Sun, Apr 21, 2013 at 10:51:39PM +0200, Borislav Petkov wrote:
> > A similar oneliner at the end of the resume path.
> >
> > Maybe have rcu suspend/resume callbacks where you can do this stuff
> > and maybe more in the future.
>
> Ok, here's one - it is pretty straight-forward using that notifier
> abomination :-). It is only in rcutree.c, it could probably be shared
> with rcutiny.c. And it has a section mismatch but I'll fix that too.
>
> It works though - two suspend/resume cycles looked ok.
Cool!!! Note that there is no need for expediting TINY_RCU because
its grace periods are already maximally expedited. There is only one
CPU, so if you are following the rules, when you call synchronize_rcu(),
by definition there is a zero-length grace period. ;-)
So all you need is rcutree.c.
Looking forward to the section-mismatch-free version!
Thanx, Paul
> --
> diff --git a/kernel/rcutree.c b/kernel/rcutree.c
> index 986d1d3a34f5..cb1f61ede2f9 100644
> --- a/kernel/rcutree.c
> +++ b/kernel/rcutree.c
> @@ -53,6 +53,7 @@
> #include <linux/delay.h>
> #include <linux/stop_machine.h>
> #include <linux/random.h>
> +#include <linux/suspend.h>
>
> #include "rcutree.h"
> #include <trace/events/rcu.h>
> @@ -3097,6 +3098,22 @@ static int __cpuinit rcu_cpu_notify(struct
> notifier_block *self,
> return NOTIFY_OK;
> }
>
> +static int __cpuinit rcu_pm_notify(struct notifier_block *self,
> + unsigned long action, void *hcpu)
> +{
> + switch (action) {
> + case PM_HIBERNATION_PREPARE:
> + rcu_expedited = 1;
> + break;
> + case PM_POST_RESTORE:
> + rcu_expedited = 0;
> + break;
> + default:
> + break;
> + }
> + return NOTIFY_OK;
> +}
> +
> /*
> * Spawn the kthread that handles this RCU flavor's grace periods.
> */
> @@ -3323,6 +3340,7 @@ void __init rcu_init(void)
> * or the scheduler are operational.
> */
> cpu_notifier(rcu_cpu_notify, 0);
> + pm_notifier(rcu_pm_notify, 0);
> for_each_online_cpu(cpu)
> rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)cpu);
> }
>
>
> --
> Regards/Gruss,
> Boris.
>
> Sent from a fat crate under my desk. Formatting is fine.
> --
>
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