Hi, On Tue 23.Feb'21 at 15:25:30 +0000, Qais Yousef wrote:
On 02/21/21 21:43, shuo.a.liu@xxxxxxxxx wrote:From: Shuo Liu <shuo.a.liu@xxxxxxxxx> 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.liu@xxxxxxxxx> Acked-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> # build-tested Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Cc: Qais Yousef <qais.yousef@xxxxxxx> --- 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
Now, the code is still in linux-next tree only.
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.
Just FYI, Greg prefers this solution. https://lore.kernel.org/lkml/20210212045724.77846-1-shuo.a.liu@xxxxxxxxx/ Thanks shuo
