On 02/21/21 21:43, shuo.a....@intel.com wrote:
> From: Shuo Liu <shuo.a....@intel.com>
>
> Without cpu hotplug support, vCPU cannot be removed from a Service VM.
> Don't expose remove_cpu sysfs when CONFIG_HOTPLUG_CPU disabled.
>
> Signed-off-by: Shuo Liu <shuo.a....@intel.com>
> Acked-by: Randy Dunlap <rdun...@infradead.org> # build-tested
> Cc: Stephen Rothwell <s...@canb.auug.org.au>
> Cc: Thomas Gleixner <t...@linutronix.de>
> Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
> Cc: Qais Yousef <qais.you...@arm.com>
> ---
> drivers/virt/acrn/hsm.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/drivers/virt/acrn/hsm.c b/drivers/virt/acrn/hsm.c
> index 1f6b7c54a1a4..6996ea6219e5 100644
> --- a/drivers/virt/acrn/hsm.c
> +++ b/drivers/virt/acrn/hsm.c
> @@ -404,6 +404,14 @@ static ssize_t remove_cpu_store(struct device *dev,
> }
> static DEVICE_ATTR_WO(remove_cpu);
>
> +static umode_t acrn_attr_visible(struct kobject *kobj, struct attribute *a,
> int n)
> +{
> + if (a == &dev_attr_remove_cpu.attr)
> + return IS_ENABLED(CONFIG_HOTPLUG_CPU) ? a->mode : 0;
> +
> + return a->mode;
> +}
> +
I can't find this code in Linus' master. But this looks fine from my narrow
PoV. Protecting the attribute with ifdef CONFIG_HOTPLUG_CPU is easier to read
for me, but this doesn't mean this approach is not fine.
Thanks
--
Qais Yousef
> static struct attribute *acrn_attrs[] = {
> &dev_attr_remove_cpu.attr,
> NULL
> @@ -411,6 +419,7 @@ static struct attribute *acrn_attrs[] = {
>
> static struct attribute_group acrn_attr_group = {
> .attrs = acrn_attrs,
> + .is_visible = acrn_attr_visible,
> };
>
> static const struct attribute_group *acrn_attr_groups[] = {
> --
> 2.28.0
>
