Re: [PATCH] driver core: bus: Return -EIO instead of 0 when show/store invalid bus attribute
From: Greg Kroah-Hartman
Date: Tue Jul 23 2024 - 13:31:17 EST
On Tue, Jul 23, 2024 at 10:55:43PM +0800, Zijun Hu wrote:
> From: Zijun Hu <quic_zijuhu@xxxxxxxxxxx>
>
> Return -EIO instead of 0 when show/store invalid bus attribute as
> class/device/driver/kobject attribute.
Why? What is this now going to break? You are changing a user-visable
api that has been this way for 20+ years, how was this tested?
>
> Signed-off-by: Zijun Hu <quic_zijuhu@xxxxxxxxxxx>
> ---
> drivers/base/bus.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/base/bus.c b/drivers/base/bus.c
> index ffea0728b8b2..e84522a90102 100644
> --- a/drivers/base/bus.c
> +++ b/drivers/base/bus.c
> @@ -152,7 +152,7 @@ static ssize_t bus_attr_show(struct kobject *kobj, struct attribute *attr,
> {
> struct bus_attribute *bus_attr = to_bus_attr(attr);
> struct subsys_private *subsys_priv = to_subsys_private(kobj);
> - ssize_t ret = 0;
> + ssize_t ret = -EIO;
>
> if (bus_attr->show)
> ret = bus_attr->show(subsys_priv->bus, buf);
> @@ -164,7 +164,7 @@ static ssize_t bus_attr_store(struct kobject *kobj, struct attribute *attr,
> {
> struct bus_attribute *bus_attr = to_bus_attr(attr);
> struct subsys_private *subsys_priv = to_subsys_private(kobj);
> - ssize_t ret = 0;
> + ssize_t ret = -EIO;
Why -EIO? What is wrong with returning an empty string?
I think I know why you picked this but you better document the heck out
of it AND test it very very well first.
thanks,
greg k-h