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Commit 31487f83 authored by Richard Weinberger's avatar Richard Weinberger Committed by Ingo Molnar
Browse files

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: default avatarRichard Weinberger <richard@nod.at>
[ Added the dropped CPU dying case back in. ]
Signed-off-by: default avatarRichard Cochran <rcochran@linutronix.de>
Signed-off-by: default avatarAnna-Maria Gleixner <anna-maria@linutronix.de>
Reviewed-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Davidlohr Bueso <dave@stgolabs>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160713153337.818376366@linutronix.de


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 6b2c2847

include/linux/cpuhotplug.h

+2 −0
Original line number Diff line number Diff line
@@ -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,

include/linux/smp.h

+5 −0
Original line number Diff line number Diff line
@@ -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 */

kernel/cpu.c

+9 −0
Original line number Diff line number Diff line
@@ -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.

kernel/smp.c

+32 −47
Original line number Diff line number Diff line
@@ -33,38 +33,33 @@ 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);

		return -ENOMEM;

	cfd->csd = alloc_percpu(struct call_single_data);

	if (!cfd->csd) {

		free_cpumask_var(cfd->cpumask);

			return notifier_from_errno(-ENOMEM);

		return -ENOMEM;

	}



	return 0;

}

		break;



#ifdef CONFIG_HOTPLUG_CPU

	case CPU_UP_CANCELED:

	case CPU_UP_CANCELED_FROZEN:

		/* Fall-through to the CPU_DEAD[_FROZEN] case. */

int smpcfd_dead_cpu(unsigned int cpu)

{

	struct call_function_data *cfd = &per_cpu(cfd_data, cpu);



	case CPU_DEAD:

	case CPU_DEAD_FROZEN:

	free_cpumask_var(cfd->cpumask);

	free_percpu(cfd->csd);

		break;

	return 0;

}



	case CPU_DYING:

	case CPU_DYING_FROZEN:

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
@@ -75,27 +70,17 @@ hotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu) 
	 * 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,

};



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());

}



/*