Hi Ben, On 05/21/2012 06:17 AM, Benjamin Herrenschmidt wrote:
> 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 <deep...@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 ? In the current design disable and enable device are called when the cpu comes online. This is to make sure that we clean up and re-register again. All the counters are reset. Not calling cpu disable when cpu goes offline currently, would only retain the counters right now. But I could add a offline check and disable the device there, if that results in cleaner design. I will test and send across the patch with couple more pseries-idle fixes soon. Thanks for your review comments ! > 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) > > > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev > _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
