From 31487f8328f20fdb302430b020a5d6e8446c1971 Mon Sep 17 00:00:00 2001 From: Richard Weinberger Date: Wed, 13 Jul 2016 17:17:01 +0000 Subject: [PATCH] smp/cfd: Convert core to hotplug state machine Install the callbacks via the state machine. They are installed at runtime so smpcfd_prepare_cpu() needs to be invoked by the boot-CPU. Signed-off-by: Richard Weinberger [ Added the dropped CPU dying case back in. ] Signed-off-by: Richard Cochran Signed-off-by: Anna-Maria Gleixner Reviewed-by: Sebastian Andrzej Siewior Cc: Davidlohr Bueso Cc: Linus Torvalds Cc: Mel Gorman Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Rasmus Villemoes Cc: Thomas Gleixner Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160713153337.818376366@linutronix.de Signed-off-by: Ingo Molnar --- include/linux/cpuhotplug.h | 2 + include/linux/smp.h | 5 +++ kernel/cpu.c | 9 +++++ kernel/smp.c | 81 ++++++++++++++++---------------------- 4 files changed, 49 insertions(+), 48 deletions(-) diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h index 78170827a776..b5cf01ace71b 100644 --- a/include/linux/cpuhotplug.h +++ b/include/linux/cpuhotplug.h @@ -18,6 +18,7 @@ enum cpuhp_state { CPUHP_HRTIMERS_PREPARE, CPUHP_PROFILE_PREPARE, CPUHP_X2APIC_PREPARE, + CPUHP_SMPCFD_PREPARE, CPUHP_TIMERS_DEAD, CPUHP_NOTIFY_PREPARE, CPUHP_BRINGUP_CPU, @@ -57,6 +58,7 @@ enum cpuhp_state { CPUHP_AP_ARM_CORESIGHT4_STARTING, CPUHP_AP_ARM64_ISNDEP_STARTING, CPUHP_AP_LEDTRIG_STARTING, + CPUHP_AP_SMPCFD_DYING, CPUHP_AP_X86_TBOOT_DYING, CPUHP_AP_NOTIFY_STARTING, CPUHP_AP_ONLINE, diff --git a/include/linux/smp.h b/include/linux/smp.h index c4414074bd88..eccae4690f41 100644 --- a/include/linux/smp.h +++ b/include/linux/smp.h @@ -196,4 +196,9 @@ extern void arch_enable_nonboot_cpus_end(void); void smp_setup_processor_id(void); +/* SMP core functions */ +int smpcfd_prepare_cpu(unsigned int cpu); +int smpcfd_dead_cpu(unsigned int cpu); +int smpcfd_dying_cpu(unsigned int cpu); + #endif /* __LINUX_SMP_H */ diff --git a/kernel/cpu.c b/kernel/cpu.c index e1017d92d308..008e2fd40cb1 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -1195,6 +1195,11 @@ static struct cpuhp_step cpuhp_bp_states[] = { .startup = hrtimers_prepare_cpu, .teardown = hrtimers_dead_cpu, }, + [CPUHP_SMPCFD_PREPARE] = { + .name = "SMPCFD prepare", + .startup = smpcfd_prepare_cpu, + .teardown = smpcfd_dead_cpu, + }, [CPUHP_TIMERS_DEAD] = { .name = "timers dead", .startup = NULL, @@ -1218,6 +1223,10 @@ static struct cpuhp_step cpuhp_bp_states[] = { .teardown = NULL, .cant_stop = true, }, + [CPUHP_AP_SMPCFD_DYING] = { + .startup = NULL, + .teardown = smpcfd_dying_cpu, + }, /* * Handled on controll processor until the plugged processor manages * this itself. diff --git a/kernel/smp.c b/kernel/smp.c index 74165443c240..7180491c9678 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -33,69 +33,54 @@ static DEFINE_PER_CPU_SHARED_ALIGNED(struct llist_head, call_single_queue); static void flush_smp_call_function_queue(bool warn_cpu_offline); -static int -hotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu) +int smpcfd_prepare_cpu(unsigned int cpu) { - long cpu = (long)hcpu; struct call_function_data *cfd = &per_cpu(cfd_data, cpu); - switch (action) { - case CPU_UP_PREPARE: - case CPU_UP_PREPARE_FROZEN: - if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL, - cpu_to_node(cpu))) - return notifier_from_errno(-ENOMEM); - cfd->csd = alloc_percpu(struct call_single_data); - if (!cfd->csd) { - free_cpumask_var(cfd->cpumask); - return notifier_from_errno(-ENOMEM); - } - break; - -#ifdef CONFIG_HOTPLUG_CPU - case CPU_UP_CANCELED: - case CPU_UP_CANCELED_FROZEN: - /* Fall-through to the CPU_DEAD[_FROZEN] case. */ - - case CPU_DEAD: - case CPU_DEAD_FROZEN: + if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL, + cpu_to_node(cpu))) + return -ENOMEM; + cfd->csd = alloc_percpu(struct call_single_data); + if (!cfd->csd) { free_cpumask_var(cfd->cpumask); - free_percpu(cfd->csd); - break; + return -ENOMEM; + } - case CPU_DYING: - case CPU_DYING_FROZEN: - /* - * The IPIs for the smp-call-function callbacks queued by other - * CPUs might arrive late, either due to hardware latencies or - * because this CPU disabled interrupts (inside stop-machine) - * before the IPIs were sent. So flush out any pending callbacks - * explicitly (without waiting for the IPIs to arrive), to - * ensure that the outgoing CPU doesn't go offline with work - * still pending. - */ - flush_smp_call_function_queue(false); - break; -#endif - }; - - return NOTIFY_OK; + return 0; } -static struct notifier_block hotplug_cfd_notifier = { - .notifier_call = hotplug_cfd, -}; +int smpcfd_dead_cpu(unsigned int cpu) +{ + struct call_function_data *cfd = &per_cpu(cfd_data, cpu); + + free_cpumask_var(cfd->cpumask); + free_percpu(cfd->csd); + return 0; +} + +int smpcfd_dying_cpu(unsigned int cpu) +{ + /* + * The IPIs for the smp-call-function callbacks queued by other + * CPUs might arrive late, either due to hardware latencies or + * because this CPU disabled interrupts (inside stop-machine) + * before the IPIs were sent. So flush out any pending callbacks + * explicitly (without waiting for the IPIs to arrive), to + * ensure that the outgoing CPU doesn't go offline with work + * still pending. + */ + flush_smp_call_function_queue(false); + return 0; +} void __init call_function_init(void) { - void *cpu = (void *)(long)smp_processor_id(); int i; for_each_possible_cpu(i) init_llist_head(&per_cpu(call_single_queue, i)); - hotplug_cfd(&hotplug_cfd_notifier, CPU_UP_PREPARE, cpu); - register_cpu_notifier(&hotplug_cfd_notifier); + smpcfd_prepare_cpu(smp_processor_id()); } /*