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Commit 215af549 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

cpu/hotplug: Online siblings when SMT control is turned on 



Writing 'off' to /sys/devices/system/cpu/smt/control offlines all SMT
siblings. Writing 'on' merily enables the abilify to online them, but does
not online them automatically.

Make 'on' more useful by onlining all offline siblings.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 390d975e

kernel/cpu.c

+24 −2
Original line number Diff line number Diff line
@@ -1979,6 +1979,15 @@ static void cpuhp_offline_cpu_device(unsigned int cpu) 
	kobject_uevent(&dev->kobj, KOBJ_OFFLINE);

}



static void cpuhp_online_cpu_device(unsigned int cpu)

{

	struct device *dev = get_cpu_device(cpu);



	dev->offline = false;

	/* Tell user space about the state change */

	kobject_uevent(&dev->kobj, KOBJ_ONLINE);

}



static int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval)

{

	int cpu, ret = 0;
@@ -2011,11 +2020,24 @@ static int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval) 
	return ret;

}



static void cpuhp_smt_enable(void)

static int cpuhp_smt_enable(void)

{

	int cpu, ret = 0;



	cpu_maps_update_begin();

	cpu_smt_control = CPU_SMT_ENABLED;

	for_each_present_cpu(cpu) {

		/* Skip online CPUs and CPUs on offline nodes */

		if (cpu_online(cpu) || !node_online(cpu_to_node(cpu)))

			continue;

		ret = _cpu_up(cpu, 0, CPUHP_ONLINE);

		if (ret)

			break;

		/* See comment in cpuhp_smt_disable() */

		cpuhp_online_cpu_device(cpu);

	}

	cpu_maps_update_done();

	return ret;

}



static ssize_t
@@ -2046,7 +2068,7 @@ store_smt_control(struct device *dev, struct device_attribute *attr, 
	if (ctrlval != cpu_smt_control) {

		switch (ctrlval) {

		case CPU_SMT_ENABLED:

			cpuhp_smt_enable();

			ret = cpuhp_smt_enable();

			break;

		case CPU_SMT_DISABLED:

		case CPU_SMT_FORCE_DISABLED: