Messages in this thread | | | Subject | Re: [PATCH] cpuidle: (POWER) Replace pseries_notify_cpuidle_add call with a elegant notifier to fix lockdep problem in start_secondary | From | Benjamin Herrenschmidt <> | Date | Mon, 21 May 2012 10:47:01 +1000 |
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On Fri, 2012-05-18 at 18:58 +0530, Deepthi Dharwar wrote: > The following patch is to remove the pseries_notify_add_cpu() call > and replace it by a hot plug notifier. > This would prevent cpuidle resources being > released and allocated each time cpu comes online on pseries. > The earlier design was causing a lockdep problem > in start_secondary as reported on this thread > -https://lkml.org/lkml/2012/5/17/2 > > This applies on 3.4-rc7 > > Signed-off-by: Deepthi Dharwar <deepthi@linux.vnet.ibm.com> > ---
Any reason why you don't do cpuidle_disable_device() when the CPU is going offline and cpuidle_enable_device() when it's coming back ?
I'm applying the patch for now since it fixes a real problem but if the above makes sense, please send a followup fix.
Cheers, Ben.
> arch/powerpc/include/asm/processor.h | 2 -- > arch/powerpc/platforms/pseries/processor_idle.c | 25 > +++++++++++++++++------ > arch/powerpc/platforms/pseries/smp.c | 1 - > 3 files changed, 19 insertions(+), 9 deletions(-) > > diff --git a/arch/powerpc/include/asm/processor.h > b/arch/powerpc/include/asm/processor.h > index 8e2d037..c6bc22b 100644 > --- a/arch/powerpc/include/asm/processor.h > +++ b/arch/powerpc/include/asm/processor.h > @@ -390,10 +390,8 @@ void cpu_idle_wait(void); > > #ifdef CONFIG_PSERIES_IDLE > extern void update_smt_snooze_delay(int snooze); > -extern int pseries_notify_cpuidle_add_cpu(int cpu); > #else > static inline void update_smt_snooze_delay(int snooze) {} > -static inline int pseries_notify_cpuidle_add_cpu(int cpu) { return 0; } > #endif > > extern void flush_instruction_cache(void); > diff --git a/arch/powerpc/platforms/pseries/processor_idle.c > b/arch/powerpc/platforms/pseries/processor_idle.c > index 41a34bc..d1a7dc0 100644 > --- a/arch/powerpc/platforms/pseries/processor_idle.c > +++ b/arch/powerpc/platforms/pseries/processor_idle.c > @@ -11,6 +11,7 @@ > #include <linux/moduleparam.h> > #include <linux/cpuidle.h> > #include <linux/cpu.h> > +#include <linux/notifier.h> > > #include <asm/paca.h> > #include <asm/reg.h> > @@ -186,17 +187,28 @@ static struct cpuidle_state > shared_states[MAX_IDLE_STATE_COUNT] = { > .enter = &shared_cede_loop }, > }; > > -int pseries_notify_cpuidle_add_cpu(int cpu) > +static int pseries_cpuidle_add_cpu_notifier(struct notifier_block *n, > + unsigned long action, void *hcpu) > { > + int hotcpu = (unsigned long)hcpu; > struct cpuidle_device *dev = > - per_cpu_ptr(pseries_cpuidle_devices, cpu); > - if (dev && cpuidle_get_driver()) { > - cpuidle_disable_device(dev); > - cpuidle_enable_device(dev); > + per_cpu_ptr(pseries_cpuidle_devices, hotcpu); > + > + switch (action & 0xf) { > + case CPU_ONLINE: > + if (dev && cpuidle_get_driver()) { > + cpuidle_disable_device(dev); > + cpuidle_enable_device(dev); > + } > + break; > } > - return 0; > + return NOTIFY_OK; > } > > +static struct notifier_block setup_hotplug_notifier = { > + .notifier_call = pseries_cpuidle_add_cpu_notifier, > +}; > + > /* > * pseries_cpuidle_driver_init() > */ > @@ -321,6 +333,7 @@ static int __init pseries_processor_idle_init(void) > return retval; > } > > + register_cpu_notifier(&setup_hotplug_notifier); > printk(KERN_DEBUG "pseries_idle_driver registered\n"); > > return 0; > diff --git a/arch/powerpc/platforms/pseries/smp.c > b/arch/powerpc/platforms/pseries/smp.c > index e16bb8d..71706bc 100644 > --- a/arch/powerpc/platforms/pseries/smp.c > +++ b/arch/powerpc/platforms/pseries/smp.c > @@ -147,7 +147,6 @@ static void __devinit smp_xics_setup_cpu(int cpu) > set_cpu_current_state(cpu, CPU_STATE_ONLINE); > set_default_offline_state(cpu); > #endif > - pseries_notify_cpuidle_add_cpu(cpu); > } > > static int __devinit smp_pSeries_kick_cpu(int nr)
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