[RFC PATCH v3 24/28] CPU: introduce busy flag to temporarily disable CPU online sysfs interface
From: Jiang Liu
Date: Sat Oct 06 2012 - 11:35:47 EST
When doing physical processor hotplug, all affected CPUs need to be
handled in atomic and shouldn't be disturbed by online/offline requests
from CPU device's online sysfs interface. So introduce a busy flag
into struct cpu to temporariliy reject requests from online sysfs
interface.
Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxx>
---
arch/ia64/include/asm/cpu.h | 2 +-
arch/ia64/kernel/topology.c | 15 +++++++++------
arch/x86/include/asm/cpu.h | 2 +-
arch/x86/kernel/topology.c | 10 ++++++----
drivers/acpi/processor_driver.c | 2 +-
drivers/base/cpu.c | 22 ++++++++++++++++++++++
drivers/xen/cpu_hotplug.c | 2 +-
include/linux/cpu.h | 2 ++
8 files changed, 43 insertions(+), 14 deletions(-)
diff --git a/arch/ia64/include/asm/cpu.h b/arch/ia64/include/asm/cpu.h
index fcca30b..192fa2f 100644
--- a/arch/ia64/include/asm/cpu.h
+++ b/arch/ia64/include/asm/cpu.h
@@ -15,7 +15,7 @@ DECLARE_PER_CPU(struct ia64_cpu, cpu_devices);
DECLARE_PER_CPU(int, cpu_state);
#ifdef CONFIG_HOTPLUG_CPU
-extern int arch_register_cpu(int num);
+extern int arch_register_cpu(int num, int busy);
extern void arch_unregister_cpu(int);
#endif
diff --git a/arch/ia64/kernel/topology.c b/arch/ia64/kernel/topology.c
index c64460b..54a6dfc 100644
--- a/arch/ia64/kernel/topology.c
+++ b/arch/ia64/kernel/topology.c
@@ -40,15 +40,17 @@ EXPORT_SYMBOL_GPL(arch_fix_phys_package_id);
#ifdef CONFIG_HOTPLUG_CPU
-int __ref arch_register_cpu(int num)
+int __ref arch_register_cpu(int num, int busy)
{
#ifdef CONFIG_ACPI
/*
* If CPEI can be re-targeted or if this is not
* CPEI target, then it is hotpluggable
*/
- if (can_cpei_retarget() || !is_cpu_cpei_target(num))
+ if (can_cpei_retarget() || !is_cpu_cpei_target(num)) {
sysfs_cpus[num].cpu.hotpluggable = 1;
+ sysfs_cpus[num].cpu.busy = busy;
+ }
map_cpu_to_node(num, node_cpuid[num].nid);
#endif
return register_cpu(&sysfs_cpus[num].cpu, num);
@@ -64,7 +66,7 @@ void __ref arch_unregister_cpu(int num)
}
EXPORT_SYMBOL(arch_unregister_cpu);
#else
-static int __init arch_register_cpu(int num)
+static int __init arch_register_cpu(int num, int busy)
{
return register_cpu(&sysfs_cpus[num].cpu, num);
}
@@ -90,10 +92,11 @@ static int __init topology_init(void)
panic("kzalloc in topology_init failed - NR_CPUS too big?");
for_each_present_cpu(i) {
- if((err = arch_register_cpu(i)))
- goto out;
+ err = arch_register_cpu(i, 0);
+ if (err)
+ break;
}
-out:
+
return err;
}
diff --git a/arch/x86/include/asm/cpu.h b/arch/x86/include/asm/cpu.h
index 4564c8e..724c777 100644
--- a/arch/x86/include/asm/cpu.h
+++ b/arch/x86/include/asm/cpu.h
@@ -26,7 +26,7 @@ struct x86_cpu {
};
#ifdef CONFIG_HOTPLUG_CPU
-extern int arch_register_cpu(int num);
+extern int arch_register_cpu(int num, int busy);
extern void arch_unregister_cpu(int);
#endif
diff --git a/arch/x86/kernel/topology.c b/arch/x86/kernel/topology.c
index 76ee977..c66ef53 100644
--- a/arch/x86/kernel/topology.c
+++ b/arch/x86/kernel/topology.c
@@ -35,7 +35,7 @@
static DEFINE_PER_CPU(struct x86_cpu, cpu_devices);
#ifdef CONFIG_HOTPLUG_CPU
-int __ref arch_register_cpu(int num)
+int __ref arch_register_cpu(int num, int busy)
{
/*
* CPU0 cannot be offlined due to several
@@ -46,8 +46,10 @@ int __ref arch_register_cpu(int num)
* Also certain PCI quirks require not to enable hotplug control
* for all CPU's.
*/
- if (num)
+ if (num) {
per_cpu(cpu_devices, num).cpu.hotpluggable = 1;
+ per_cpu(cpu_devices, num).cpu.busy = busy;
+ }
return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
}
@@ -60,7 +62,7 @@ void arch_unregister_cpu(int num)
EXPORT_SYMBOL(arch_unregister_cpu);
#else /* CONFIG_HOTPLUG_CPU */
-static int __init arch_register_cpu(int num)
+static int __init arch_register_cpu(int num, int busy)
{
return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
}
@@ -76,7 +78,7 @@ static int __init topology_init(void)
#endif
for_each_present_cpu(i)
- arch_register_cpu(i);
+ arch_register_cpu(i, 0);
return 0;
}
diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
index 25079ca..447bd6d 100644
--- a/drivers/acpi/processor_driver.c
+++ b/drivers/acpi/processor_driver.c
@@ -702,7 +702,7 @@ static int acpi_processor_pre_configure(struct acpi_device *device,
if (result)
goto out_unlock;
BUG_ON((pr->id >= nr_cpu_ids) || (pr->id < 0));
- result = arch_register_cpu(pr->id);
+ result = arch_register_cpu(pr->id, 0);
if (result)
goto out_unmap;
diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 6345294..dc6246c 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -42,6 +42,11 @@ static ssize_t __ref store_online(struct device *dev,
ssize_t ret;
cpu_hotplug_driver_lock();
+ if (cpu->busy) {
+ ret = -EBUSY;
+ goto out;
+ }
+
switch (buf[0]) {
case '0':
ret = cpu_down(cpu->dev.id);
@@ -56,6 +61,8 @@ static ssize_t __ref store_online(struct device *dev,
default:
ret = -EINVAL;
}
+
+out:
cpu_hotplug_driver_unlock();
if (ret >= 0)
@@ -308,6 +315,21 @@ bool cpu_is_hotpluggable(unsigned cpu)
}
EXPORT_SYMBOL_GPL(cpu_is_hotpluggable);
+int cpu_set_busy(unsigned int id, int busy)
+{
+ int old;
+ struct device *device = get_cpu_device(id);
+ struct cpu *cpu = container_of(device, struct cpu, dev);
+
+ cpu_hotplug_driver_lock();
+ old = cpu->busy;
+ cpu->busy = busy;
+ cpu_hotplug_driver_unlock();
+
+ return old;
+}
+EXPORT_SYMBOL_GPL(cpu_set_busy);
+
#ifdef CONFIG_GENERIC_CPU_DEVICES
static DEFINE_PER_CPU(struct cpu, cpu_devices);
#endif
diff --git a/drivers/xen/cpu_hotplug.c b/drivers/xen/cpu_hotplug.c
index 4dcfced..95bde8a 100644
--- a/drivers/xen/cpu_hotplug.c
+++ b/drivers/xen/cpu_hotplug.c
@@ -9,7 +9,7 @@
static void enable_hotplug_cpu(int cpu)
{
if (!cpu_present(cpu))
- arch_register_cpu(cpu);
+ arch_register_cpu(cpu, 0);
set_cpu_present(cpu, true);
}
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index ce7a074..557501b 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -23,12 +23,14 @@ struct device;
struct cpu {
int node_id; /* The node which contains the CPU */
int hotpluggable; /* creates sysfs control file if hotpluggable */
+ int busy;
struct device dev;
};
extern int register_cpu(struct cpu *cpu, int num);
extern struct device *get_cpu_device(unsigned cpu);
extern bool cpu_is_hotpluggable(unsigned cpu);
+extern int cpu_set_busy(unsigned int cpu, int busy);
extern int cpu_add_dev_attr(struct device_attribute *attr);
extern void cpu_remove_dev_attr(struct device_attribute *attr);
--
1.7.9.5
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/