Commit 33c3736e authored by Qais Yousef's avatar Qais Yousef Committed by Thomas Gleixner
Browse files

cpu/hotplug: Hide cpu_up/down() 



Use separate functions for the device core to bring a CPU up and down.

Users outside the device core must use add/remove_cpu() which will take
care of extra housekeeping work like keeping sysfs in sync.

Make cpu_up/down() static and replace the extra layer of indirection.

[ tglx: Removed the extra wrapper functions and adjusted function names ]

Signed-off-by: default avatarQais Yousef <qais.yousef@arm.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200323135110.30522-18-qais.yousef@arm.com
parent b99a2659

drivers/base/cpu.c

+2 −2
Original line number Diff line number Diff line
@@ -55,7 +55,7 @@ static int cpu_subsys_online(struct device *dev) 
	if (from_nid == NUMA_NO_NODE)

		return -ENODEV;



	ret = cpu_up(cpuid);

	ret = cpu_device_up(dev);

	/*

	 * When hot adding memory to memoryless node and enabling a cpu

	 * on the node, node number of the cpu may internally change.
@@ -69,7 +69,7 @@ static int cpu_subsys_online(struct device *dev) 


static int cpu_subsys_offline(struct device *dev)

{

	return cpu_down(dev->id);

	return cpu_device_down(dev);

}



void unregister_cpu(struct cpu *cpu)

include/linux/cpu.h

+2 −2
Original line number Diff line number Diff line
@@ -88,8 +88,8 @@ extern ssize_t arch_cpu_release(const char *, size_t); 


#ifdef CONFIG_SMP

extern bool cpuhp_tasks_frozen;

int cpu_up(unsigned int cpu);

int add_cpu(unsigned int cpu);

int cpu_device_up(struct device *dev);

void notify_cpu_starting(unsigned int cpu);

extern void cpu_maps_update_begin(void);

extern void cpu_maps_update_done(void);
@@ -120,8 +120,8 @@ extern void lockdep_assert_cpus_held(void); 
extern void cpu_hotplug_disable(void);

extern void cpu_hotplug_enable(void);

void clear_tasks_mm_cpumask(int cpu);

int cpu_down(unsigned int cpu);

int remove_cpu(unsigned int cpu);

int cpu_device_down(struct device *dev);

extern void smp_shutdown_nonboot_cpus(unsigned int primary_cpu);



#else /* CONFIG_HOTPLUG_CPU */

kernel/cpu.c

+28 −14
Original line number Diff line number Diff line
@@ -1041,7 +1041,7 @@ static int cpu_down_maps_locked(unsigned int cpu, enum cpuhp_state target) 
	return _cpu_down(cpu, 0, target);

}



static int do_cpu_down(unsigned int cpu, enum cpuhp_state target)

static int cpu_down(unsigned int cpu, enum cpuhp_state target)

{

	int err;
@@ -1051,11 +1051,18 @@ static int do_cpu_down(unsigned int cpu, enum cpuhp_state target) 
	return err;

}



int cpu_down(unsigned int cpu)

/**

 * cpu_device_down - Bring down a cpu device

 * @dev: Pointer to the cpu device to offline

 *

 * This function is meant to be used by device core cpu subsystem only.

 *

 * Other subsystems should use remove_cpu() instead.

 */

int cpu_device_down(struct device *dev)

{

	return do_cpu_down(cpu, CPUHP_OFFLINE);

	return cpu_down(dev->id, CPUHP_OFFLINE);

}

EXPORT_SYMBOL(cpu_down);



int remove_cpu(unsigned int cpu)

{
@@ -1178,8 +1185,8 @@ static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target) 
	}



	/*

	 * The caller of do_cpu_up might have raced with another

	 * caller. Ignore it for now.

	 * The caller of cpu_up() might have raced with another

	 * caller. Nothing to do.

	 */

	if (st->state >= target)

		goto out;
@@ -1223,7 +1230,7 @@ out: 
	return ret;

}



static int do_cpu_up(unsigned int cpu, enum cpuhp_state target)

static int cpu_up(unsigned int cpu, enum cpuhp_state target)

{

	int err = 0;
@@ -1257,11 +1264,18 @@ out: 
	return err;

}



int cpu_up(unsigned int cpu)

/**

 * cpu_device_up - Bring up a cpu device

 * @dev: Pointer to the cpu device to online

 *

 * This function is meant to be used by device core cpu subsystem only.

 *

 * Other subsystems should use add_cpu() instead.

 */

int cpu_device_up(struct device *dev)

{

	return do_cpu_up(cpu, CPUHP_ONLINE);

	return cpu_up(dev->id, CPUHP_ONLINE);

}

EXPORT_SYMBOL_GPL(cpu_up);



int add_cpu(unsigned int cpu)

{
@@ -1289,7 +1303,7 @@ int bringup_hibernate_cpu(unsigned int sleep_cpu) 


	if (!cpu_online(sleep_cpu)) {

		pr_info("Hibernated on a CPU that is offline! Bringing CPU up.\n");

		ret = cpu_up(sleep_cpu);

		ret = cpu_up(sleep_cpu, CPUHP_ONLINE);

		if (ret) {

			pr_err("Failed to bring hibernate-CPU up!\n");

			return ret;
@@ -1306,7 +1320,7 @@ void bringup_nonboot_cpus(unsigned int setup_max_cpus) 
		if (num_online_cpus() >= setup_max_cpus)

			break;

		if (!cpu_online(cpu))

			cpu_up(cpu);

			cpu_up(cpu, CPUHP_ONLINE);

	}

}
@@ -2129,9 +2143,9 @@ static ssize_t write_cpuhp_target(struct device *dev, 
		goto out;



	if (st->state < target)

		ret = do_cpu_up(dev->id, target);

		ret = cpu_up(dev->id, target);

	else

		ret = do_cpu_down(dev->id, target);

		ret = cpu_down(dev->id, target);

out:

	unlock_device_hotplug();

	return ret ? ret : count;

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