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
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