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driver-core/cpu: Expose hotpluggability to the rest of the kernel

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When architectures register CPUs, they indicate whether the CPU allows
hotplugging; notably, x86 and ARM don't allow hotplugging CPU 0.
Userspace can easily query the hotpluggability of a CPU via sysfs;
however, the kernel has no convenient way of accessing that property in
an architecture-independent way.  While the kernel can simply try it and
see, some code needs to distinguish between "hotplug failed" and
"hotplug has no hope of working on this CPU"; for example, rcutorture's
CPU hotplug tests want to avoid drowning out real hotplug failures with
expected failures.

Expose this property via a new cpu_is_hotpluggable function, so that the
rest of the kernel can access it in an architecture-independent way.

Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Josh Triplett 2011-12-03 13:06:50 -08:00 committed by Paul E. McKenney
parent 2d1dc9a600
commit 2987557f52
2 changed files with 8 additions and 0 deletions
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7
drivers/base/cpu.c
View File

@ -247,6 +247,13 @@ struct sys_device *get_cpu_sysdev(unsigned cpu)
}
EXPORT_SYMBOL_GPL(get_cpu_sysdev);
bool cpu_is_hotpluggable(unsigned cpu)
{
struct sys_device *dev = get_cpu_sysdev(cpu);
return dev && container_of(dev, struct cpu, sysdev)->hotpluggable;
}
EXPORT_SYMBOL_GPL(cpu_is_hotpluggable);
int __init cpu_dev_init(void)
{
int err;

1
include/linux/cpu.h
View File

@ -27,6 +27,7 @@ struct cpu {
extern int register_cpu(struct cpu *cpu, int num);
extern struct sys_device *get_cpu_sysdev(unsigned cpu);
extern bool cpu_is_hotpluggable(unsigned cpu);
extern int cpu_add_sysdev_attr(struct sysdev_attribute *attr);
extern void cpu_remove_sysdev_attr(struct sysdev_attribute *attr);