cpuidle: (POWER) Replace pseries_notify_cpuidle_add call with a notifier to fix lockdep problem in start_secondary
From: Deepthi Dharwar <deep...@linux.vnet.ibm.com> Currently the call to pseries_notify_cpuidle_add(), that takes action on the cpuidle front when a cpu is added/removed is being made from smp_xics_setup_cpu(). This works fine when the cpus were hot added/removed once the system is up but causes lockdep issues as reported https://lkml.org/lkml/2012/5/17/2 during the time of boot. During boot, on addition of each cpu, resources were cleared and re-allocated each time, all in critical section as part of start_secondary() which had interrupts disabled. To resolve this issue, replacing the pseries_notify_cpuidle_add_cpu() call with a hotplug notifier. This would prevent cpuidle resources from being released and allocated each time cpu is onlined during pseries bootup. Signed-off-by: Deepthi Dharwar <deep...@linux.vnet.ibm.com> Reported-by: Paul E. McKenney <paul...@linux.vnet.ibm.com> Reviewed-by: Srivatsa S. Bhat <srivatsa.b...@linux.vnet.ibm.com> --- This patch has in-corporated review comments received on the earlier version posted. v1 -> https://lkml.org/lkml/2012/5/18/174 This applies on 3.5-rc5 --- arch/powerpc/include/asm/processor.h | 2 - arch/powerpc/platforms/pseries/processor_idle.c | 35 ++++++++++++++++++++--- arch/powerpc/platforms/pseries/smp.c | 1 - 3 files changed, 30 insertions(+), 8 deletions(-) diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h index 413a5ea..53b6dfa 100644 --- a/arch/powerpc/include/asm/processor.h +++ b/arch/powerpc/include/asm/processor.h @@ -389,10 +389,8 @@ extern int powersave_nap; /* set if nap mode can be used in idle loop */ #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 e61483e..da245c0 100644 --- a/arch/powerpc/platforms/pseries/processor_idle.c +++ b/arch/powerpc/platforms/pseries/processor_idle.c @@ -186,17 +186,40 @@ 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); + per_cpu_ptr(pseries_cpuidle_devices, hotcpu); + if (dev && cpuidle_get_driver()) { - cpuidle_disable_device(dev); - cpuidle_enable_device(dev); + switch (action) { + case CPU_ONLINE: + case CPU_ONLINE_FROZEN: + cpuidle_pause_and_lock(); + cpuidle_enable_device(dev); + cpuidle_resume_and_unlock(); + break; + + case CPU_DEAD: + case CPU_DEAD_FROZEN: + cpuidle_pause_and_lock(); + cpuidle_disable_device(dev); + cpuidle_resume_and_unlock(); + break; + + default: + return NOTIFY_DONE; + } } - 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 +344,7 @@ 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; @@ -329,6 +353,7 @@ static int __init pseries_processor_idle_init(void) static void __exit pseries_processor_idle_exit(void) { + unregister_cpu_notifier(&setup_hotplug_notifier); pseries_idle_devices_uninit(); cpuidle_unregister_driver(&pseries_idle_driver); 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
