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Commit 34f361ad authored by Ashok Raj's avatar Ashok Raj Committed by Linus Torvalds
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[PATCH] Check if cpu can be onlined before calling smp_prepare_cpu() 



- Moved check for online cpu out of smp_prepare_cpu()

- Moved default declaration of smp_prepare_cpu() to kernel/cpu.c

- Removed lock_cpu_hotplug() from smp_prepare_cpu() to around it, since
  its called from cpu_up() as well now.

- Removed clearing from cpu_present_map during cpu_offline as it breaks
  using cpu_up() directly during a subsequent online operation.

Signed-off-by: default avatarAshok Raj <ashok.raj@intel.com>
Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: "Li, Shaohua" <shaohua.li@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent f1a1c2dc

arch/i386/kernel/smpboot.c

+18 −15
Original line number Diff line number Diff line
@@ -1003,7 +1003,6 @@ void cpu_exit_clear(void) 


	cpu_clear(cpu, cpu_callout_map);

	cpu_clear(cpu, cpu_callin_map);

	cpu_clear(cpu, cpu_present_map);



	cpu_clear(cpu, smp_commenced_mask);

	unmap_cpu_to_logical_apicid(cpu);
@@ -1015,31 +1014,20 @@ struct warm_boot_cpu_info { 
	int cpu;

};



static void __devinit do_warm_boot_cpu(void *p)

static void __cpuinit do_warm_boot_cpu(void *p)

{

	struct warm_boot_cpu_info *info = p;

	do_boot_cpu(info->apicid, info->cpu);

	complete(info->complete);

}



int __devinit smp_prepare_cpu(int cpu)

static int __cpuinit __smp_prepare_cpu(int cpu)

{

	DECLARE_COMPLETION(done);

	struct warm_boot_cpu_info info;

	struct work_struct task;

	int	apicid, ret;



	lock_cpu_hotplug();



	/*

	 * On x86, CPU0 is never offlined.  Trying to bring up an

	 * already-booted CPU will hang.  So check for that case.

	 */

	if (cpu_online(cpu)) {

		ret = -EINVAL;

		goto exit;

	}



	apicid = x86_cpu_to_apicid[cpu];

	if (apicid == BAD_APICID) {

		ret = -ENODEV;
@@ -1064,7 +1052,6 @@ int __devinit smp_prepare_cpu(int cpu) 
	zap_low_mappings();

	ret = 0;

exit:

	unlock_cpu_hotplug();

	return ret;

}

#endif
@@ -1392,6 +1379,22 @@ void __cpu_die(unsigned int cpu) 


int __devinit __cpu_up(unsigned int cpu)

{

#ifdef CONFIG_HOTPLUG_CPU

	int ret=0;



	/*

	 * We do warm boot only on cpus that had booted earlier

	 * Otherwise cold boot is all handled from smp_boot_cpus().

	 * cpu_callin_map is set during AP kickstart process. Its reset

	 * when a cpu is taken offline from cpu_exit_clear().

	 */

	if (!cpu_isset(cpu, cpu_callin_map))

		ret = __smp_prepare_cpu(cpu);



	if (ret)

		return -EIO;

#endif



	/* In case one didn't come up */

	if (!cpu_isset(cpu, cpu_callin_map)) {

		printk(KERN_DEBUG "skipping cpu%d, didn't come online\n", cpu);

drivers/base/cpu.c

+1 −8
Original line number Diff line number Diff line
@@ -19,11 +19,6 @@ EXPORT_SYMBOL(cpu_sysdev_class); 
static struct sys_device *cpu_sys_devices[NR_CPUS];



#ifdef CONFIG_HOTPLUG_CPU

int __attribute__((weak)) smp_prepare_cpu (int cpu)

{

	return 0;

}



static ssize_t show_online(struct sys_device *dev, char *buf)

{

	struct cpu *cpu = container_of(dev, struct cpu, sysdev);
@@ -44,8 +39,6 @@ static ssize_t store_online(struct sys_device *dev, const char *buf, 
			kobject_uevent(&dev->kobj, KOBJ_OFFLINE);

		break;

	case '1':

		ret = smp_prepare_cpu(cpu->sysdev.id);

		if (!ret)

		ret = cpu_up(cpu->sysdev.id);

		if (!ret)

			kobject_uevent(&dev->kobj, KOBJ_ONLINE);

include/linux/cpu.h

+0 −1
Original line number Diff line number Diff line
@@ -74,7 +74,6 @@ extern int lock_cpu_hotplug_interruptible(void); 
	register_cpu_notifier(&fn##_nb);			\

}

int cpu_down(unsigned int cpu);

extern int __attribute__((weak)) smp_prepare_cpu(int cpu);

#define cpu_is_offline(cpu) unlikely(!cpu_online(cpu))

#else

#define lock_cpu_hotplug()	do { } while (0)

kernel/power/smp.c

+1 −3
Original line number Diff line number Diff line
@@ -49,8 +49,6 @@ void enable_nonboot_cpus(void) 


	printk("Thawing cpus ...\n");

	for_each_cpu_mask(cpu, frozen_cpus) {

		error = smp_prepare_cpu(cpu);

		if (!error)

		error = cpu_up(cpu);

		if (!error) {

			printk("CPU%d is up\n", cpu);