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Commit 12633e80 authored by Nathan Fontenot's avatar Nathan Fontenot Committed by Benjamin Herrenschmidt
Browse files

sysfs/cpu: Add probe/release files 



Version 3 of this patch is updated with documentation added to
Documentation/ABI.  There are no changes to any of the C code from v2
of the patch.

In order to support kernel DLPAR of CPU resources we need to provide an
interface to add (probe) and remove (release) the resource from the system.
This patch Creates new generic probe and release sysfs files to facilitate
cpu probe/release.  The probe/release interface provides for allowing each
arch to supply their own routines for implementing the backend of adding
and removing cpus to/from the system.

This also creates the powerpc specific stubs to handle the arch callouts
from writes to the sysfs files.

The creation and use of these files is regulated by the
CONFIG_ARCH_CPU_PROBE_RELEASE option so that only architectures that need the
capability will have the files created.

Signed-off-by: default avatarNathan Fontenot <nfont@austin.ibm.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent ab519a01

Documentation/ABI/testing/sysfs-devices-system-cpu

+15 −0
Original line number Original line Diff line number Diff line
@@ -62,6 +62,21 @@ Description: CPU topology files that describe kernel limits related to 
		See Documentation/cputopology.txt for more information.

		See Documentation/cputopology.txt for more information.









What:		/sys/devices/system/cpu/probe

		/sys/devices/system/cpu/release

Date:		November 2009

Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>

Description:	Dynamic addition and removal of CPU's.  This is not hotplug

		removal, this is meant complete removal/addition of the CPU

		from the system.



		probe: writes to this file will dynamically add a CPU to the

		system.  Information written to the file to add CPU's is

		architecture specific.



		release: writes to this file dynamically remove a CPU from

		the system.  Information writtento the file to remove CPU's

		is architecture specific.





What:		/sys/devices/system/cpu/cpu#/node

What:		/sys/devices/system/cpu/cpu#/node

Date:		October 2009

Date:		October 2009

arch/powerpc/Kconfig

+4 −0
Original line number Original line Diff line number Diff line
@@ -320,6 +320,10 @@ config HOTPLUG_CPU 




	  Say N if you are unsure.

	  Say N if you are unsure.





config ARCH_CPU_PROBE_RELEASE

	def_bool y

	depends on HOTPLUG_CPU



config ARCH_ENABLE_MEMORY_HOTPLUG

config ARCH_ENABLE_MEMORY_HOTPLUG

	def_bool y

	def_bool y

arch/powerpc/include/asm/machdep.h

+5 −0
Original line number Original line Diff line number Diff line
@@ -266,6 +266,11 @@ struct machdep_calls { 
	void (*suspend_disable_irqs)(void);

	void (*suspend_disable_irqs)(void);

	void (*suspend_enable_irqs)(void);

	void (*suspend_enable_irqs)(void);

#endif

#endif



#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE

	ssize_t (*cpu_probe)(const char *, size_t);

	ssize_t (*cpu_release)(const char *, size_t);

#endif

};

};





extern void e500_idle(void);

extern void e500_idle(void);

arch/powerpc/kernel/sysfs.c

+19 −0
Original line number Original line Diff line number Diff line
@@ -461,6 +461,25 @@ static void unregister_cpu_online(unsigned int cpu) 




	cacheinfo_cpu_offline(cpu);

	cacheinfo_cpu_offline(cpu);

}

}



#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE

ssize_t arch_cpu_probe(const char *buf, size_t count)

{

	if (ppc_md.cpu_probe)

		return ppc_md.cpu_probe(buf, count);



	return -EINVAL;

}



ssize_t arch_cpu_release(const char *buf, size_t count)

{

	if (ppc_md.cpu_release)

		return ppc_md.cpu_release(buf, count);



	return -EINVAL;

}

#endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */



#endif /* CONFIG_HOTPLUG_CPU */

#endif /* CONFIG_HOTPLUG_CPU */





static int __cpuinit sysfs_cpu_notify(struct notifier_block *self,

static int __cpuinit sysfs_cpu_notify(struct notifier_block *self,

drivers/base/cpu.c

+32 −0
Original line number Original line Diff line number Diff line
@@ -72,6 +72,38 @@ void unregister_cpu(struct cpu *cpu) 
	per_cpu(cpu_sys_devices, logical_cpu) = NULL;

	per_cpu(cpu_sys_devices, logical_cpu) = NULL;

	return;

	return;

}

}



#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE

static ssize_t cpu_probe_store(struct class *class, const char *buf,

			       size_t count)

{

	return arch_cpu_probe(buf, count);

}



static ssize_t cpu_release_store(struct class *class, const char *buf,

				 size_t count)

{

	return arch_cpu_release(buf, count);

}



static CLASS_ATTR(probe, S_IWUSR, NULL, cpu_probe_store);

static CLASS_ATTR(release, S_IWUSR, NULL, cpu_release_store);



int __init cpu_probe_release_init(void)

{

	int rc;



	rc = sysfs_create_file(&cpu_sysdev_class.kset.kobj,

			       &class_attr_probe.attr);

	if (!rc)

		rc = sysfs_create_file(&cpu_sysdev_class.kset.kobj,

				       &class_attr_release.attr);



	return rc;

}

device_initcall(cpu_probe_release_init);

#endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */



#else /* ... !CONFIG_HOTPLUG_CPU */

#else /* ... !CONFIG_HOTPLUG_CPU */

static inline void register_cpu_control(struct cpu *cpu)

static inline void register_cpu_control(struct cpu *cpu)

{

{