From 12633e803a2a556f6469e0933d08233d0844a2d9 Mon Sep 17 00:00:00 2001 From: Nathan Fontenot Date: Wed, 25 Nov 2009 17:23:25 +0000 Subject: [PATCH] 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: Nathan Fontenot Signed-off-by: Benjamin Herrenschmidt --- .../ABI/testing/sysfs-devices-system-cpu | 15 +++++++++ arch/powerpc/Kconfig | 4 +++ arch/powerpc/include/asm/machdep.h | 5 +++ arch/powerpc/kernel/sysfs.c | 19 +++++++++++ drivers/base/cpu.c | 32 +++++++++++++++++++ include/linux/cpu.h | 2 ++ 6 files changed, 77 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu index a703b9e9aeb..d868a11c94a 100644 --- a/Documentation/ABI/testing/sysfs-devices-system-cpu +++ b/Documentation/ABI/testing/sysfs-devices-system-cpu @@ -62,6 +62,21 @@ Description: CPU topology files that describe kernel limits related to 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 +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 Date: October 2009 diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 5dbd375a3f2..0df57466e78 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -320,6 +320,10 @@ config HOTPLUG_CPU Say N if you are unsure. +config ARCH_CPU_PROBE_RELEASE + def_bool y + depends on HOTPLUG_CPU + config ARCH_ENABLE_MEMORY_HOTPLUG def_bool y diff --git a/arch/powerpc/include/asm/machdep.h b/arch/powerpc/include/asm/machdep.h index 9efa2be7833..9f0fc9e6ce0 100644 --- a/arch/powerpc/include/asm/machdep.h +++ b/arch/powerpc/include/asm/machdep.h @@ -266,6 +266,11 @@ struct machdep_calls { void (*suspend_disable_irqs)(void); void (*suspend_enable_irqs)(void); #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); diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c index 956ab33fd73..e235e52dc4f 100644 --- a/arch/powerpc/kernel/sysfs.c +++ b/arch/powerpc/kernel/sysfs.c @@ -461,6 +461,25 @@ static void unregister_cpu_online(unsigned int 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 */ static int __cpuinit sysfs_cpu_notify(struct notifier_block *self, diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c index e62a4ccea54..7c03af7b84a 100644 --- a/drivers/base/cpu.c +++ b/drivers/base/cpu.c @@ -72,6 +72,38 @@ void unregister_cpu(struct cpu *cpu) per_cpu(cpu_sys_devices, logical_cpu) = NULL; 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 */ static inline void register_cpu_control(struct cpu *cpu) { diff --git a/include/linux/cpu.h b/include/linux/cpu.h index 47536197ffd..c972f7ccb7d 100644 --- a/include/linux/cpu.h +++ b/include/linux/cpu.h @@ -43,6 +43,8 @@ extern int sched_create_sysfs_power_savings_entries(struct sysdev_class *cls); #ifdef CONFIG_HOTPLUG_CPU extern void unregister_cpu(struct cpu *cpu); +extern ssize_t arch_cpu_probe(const char *, size_t); +extern ssize_t arch_cpu_release(const char *, size_t); #endif struct notifier_block;