Interface for bulk cpu removal. It's /sys/devices/system/cpu/cpu_bulk_remove
Signed-off-by: Shaohua Li <[email protected]>
---
linux-2.6.17-rc3-root/drivers/base/cpu.c | 47 +++++++++++++++++++++++++++++-
linux-2.6.17-rc3-root/include/linux/cpu.h | 3 +
2 files changed, 49 insertions(+), 1 deletion(-)
diff -puN drivers/base/cpu.c~bulk_cpu_remove_interface drivers/base/cpu.c
--- linux-2.6.17-rc3/drivers/base/cpu.c~bulk_cpu_remove_interface 2006-05-07 07:47:02.000000000 +0800
+++ linux-2.6.17-rc3-root/drivers/base/cpu.c 2006-05-07 09:29:54.000000000 +0800
@@ -76,6 +76,46 @@ static inline void register_cpu_control(
}
#endif /* CONFIG_HOTPLUG_CPU */
+#ifdef CONFIG_BULK_CPU_REMOVE
+static ssize_t cpu_bulk_remove_show(struct sysdev_class *c, char *buf)
+{
+ int len;
+
+ len = cpulist_scnprintf(buf, PAGE_SIZE-1, cpu_online_map);
+ len += sprintf(buf + len, "\n");
+ return len;
+}
+
+static ssize_t cpu_bulk_remove_store(struct sysdev_class *c,
+ const char *buf, size_t count)
+{
+ int err;
+ cpumask_t removed_cpus;
+
+ if ((err = lock_cpu_hotplug_interruptible() != 0))
+ return err;
+ err = cpulist_parse(buf, removed_cpus);
+ if (err) {
+ unlock_cpu_hotplug();
+ return err;
+ }
+
+ unlock_cpu_hotplug();
+ cpu_down_mask(removed_cpus);
+ return count;
+}
+
+static SYSDEV_CLASS_ATTR(cpu_bulk_remove, 0600, cpu_bulk_remove_show,
+ cpu_bulk_remove_store);
+
+void __init cpu_bulk_remove_sysfs_init(void)
+{
+ sysdev_class_create_file(&cpu_sysdev_class, &attr_cpu_bulk_remove);
+}
+#else
+#define cpu_bulk_remove_sysfs_init()
+#endif
+
#ifdef CONFIG_KEXEC
#include <linux/kexec.h>
@@ -145,5 +185,10 @@ EXPORT_SYMBOL_GPL(get_cpu_sysdev);
int __init cpu_dev_init(void)
{
- return sysdev_class_register(&cpu_sysdev_class);
+ int ret;
+
+ ret = sysdev_class_register(&cpu_sysdev_class);
+ if (!ret)
+ cpu_bulk_remove_sysfs_init();
+ return ret;
}
diff -puN include/linux/cpu.h~bulk_cpu_remove_interface include/linux/cpu.h
--- linux-2.6.17-rc3/include/linux/cpu.h~bulk_cpu_remove_interface 2006-05-07 07:47:02.000000000 +0800
+++ linux-2.6.17-rc3-root/include/linux/cpu.h 2006-05-07 07:47:02.000000000 +0800
@@ -74,6 +74,9 @@ extern int lock_cpu_hotplug_interruptibl
register_cpu_notifier(&fn##_nb); \
}
int cpu_down(unsigned int cpu);
+#ifdef CONFIG_BULK_CPU_REMOVE
+int cpu_down_mask(cpumask_t remove_mask);
+#endif
#define cpu_is_offline(cpu) unlikely(!cpu_online(cpu))
#else
#define lock_cpu_hotplug() do { } while (0)
_
Shaohua Li wrote:
>
> Interface for bulk cpu removal. It's /sys/devices/system/cpu/cpu_bulk_remove
>
> Signed-off-by: Shaohua Li <[email protected]>
> ---
>
> linux-2.6.17-rc3-root/drivers/base/cpu.c | 47 +++++++++++++++++++++++++++++-
> linux-2.6.17-rc3-root/include/linux/cpu.h | 3 +
> 2 files changed, 49 insertions(+), 1 deletion(-)
>
> diff -puN drivers/base/cpu.c~bulk_cpu_remove_interface drivers/base/cpu.c
> --- linux-2.6.17-rc3/drivers/base/cpu.c~bulk_cpu_remove_interface 2006-05-07 07:47:02.000000000 +0800
> +++ linux-2.6.17-rc3-root/drivers/base/cpu.c 2006-05-07 09:29:54.000000000 +0800
> @@ -76,6 +76,46 @@ static inline void register_cpu_control(
> }
> #endif /* CONFIG_HOTPLUG_CPU */
>
> +#ifdef CONFIG_BULK_CPU_REMOVE
> +static ssize_t cpu_bulk_remove_show(struct sysdev_class *c, char *buf)
> +{
> + int len;
> +
> + len = cpulist_scnprintf(buf, PAGE_SIZE-1, cpu_online_map);
> + len += sprintf(buf + len, "\n");
> + return len;
> +}
This doesn't really seem meaningful. I'd say the attribute could do
without a show method.
> +static ssize_t cpu_bulk_remove_store(struct sysdev_class *c,
> + const char *buf, size_t count)
> +{
> + int err;
> + cpumask_t removed_cpus;
> +
> + if ((err = lock_cpu_hotplug_interruptible() != 0))
> + return err;
> + err = cpulist_parse(buf, removed_cpus);
> + if (err) {
> + unlock_cpu_hotplug();
> + return err;
> + }
> +
> + unlock_cpu_hotplug();
> + cpu_down_mask(removed_cpus);
> + return count;
> +}
Shouldn't this make sure that we don't offline all cpus?
Why are you using lock_cpu_hotplug_interruptible instead of
lock_cpu_hotplug?
Why is only the parsing of the cpumask buffer protected by the cpu
hotplug lock? Shouldn't cpu_down_mask be called with the lock held?
Can cpu_down_mask fail, and if so, shouldn't we be reporting the
error?
On Mon, 2006-05-08 at 01:31 -0500, Nathan Lynch wrote:
> Shaohua Li wrote:
> >
> > Interface for bulk cpu removal. It's /sys/devices/system/cpu/cpu_bulk_remove
> >
> > Signed-off-by: Shaohua Li <[email protected]>
> > ---
> >
> > linux-2.6.17-rc3-root/drivers/base/cpu.c | 47 +++++++++++++++++++++++++++++-
> > linux-2.6.17-rc3-root/include/linux/cpu.h | 3 +
> > 2 files changed, 49 insertions(+), 1 deletion(-)
> >
> > diff -puN drivers/base/cpu.c~bulk_cpu_remove_interface drivers/base/cpu.c
> > --- linux-2.6.17-rc3/drivers/base/cpu.c~bulk_cpu_remove_interface 2006-05-07 07:47:02.000000000 +0800
> > +++ linux-2.6.17-rc3-root/drivers/base/cpu.c 2006-05-07 09:29:54.000000000 +0800
> > @@ -76,6 +76,46 @@ static inline void register_cpu_control(
> > }
> > #endif /* CONFIG_HOTPLUG_CPU */
> >
> > +#ifdef CONFIG_BULK_CPU_REMOVE
> > +static ssize_t cpu_bulk_remove_show(struct sysdev_class *c, char *buf)
> > +{
> > + int len;
> > +
> > + len = cpulist_scnprintf(buf, PAGE_SIZE-1, cpu_online_map);
> > + len += sprintf(buf + len, "\n");
> > + return len;
> > +}
>
> This doesn't really seem meaningful. I'd say the attribute could do
> without a show method.
Ok, I'll remove it.
> > +static ssize_t cpu_bulk_remove_store(struct sysdev_class *c,
> > + const char *buf, size_t count)
> > +{
> > + int err;
> > + cpumask_t removed_cpus;
> > +
> > + if ((err = lock_cpu_hotplug_interruptible() != 0))
> > + return err;
> > + err = cpulist_parse(buf, removed_cpus);
> > + if (err) {
> > + unlock_cpu_hotplug();
> > + return err;
> > + }
> > +
> > + unlock_cpu_hotplug();
> > + cpu_down_mask(removed_cpus);
> > + return count;
> > +}
>
> Shouldn't this make sure that we don't offline all cpus?
cpu_down_mask will check it.
> Why are you using lock_cpu_hotplug_interruptible instead of
> lock_cpu_hotplug?
>
> Why is only the parsing of the cpumask buffer protected by the cpu
> hotplug lock? Shouldn't cpu_down_mask be called with the lock held?
we actually don't need lock here. I'll remove it.
> Can cpu_down_mask fail, and if so, shouldn't we be reporting the
> error?
Makes sense.
Thanks,
Shaohua