Re: [PATCH 1/5] ACPI: battery: Do not unload battery hooks on single error

From: Rafael J. Wysocki
Date: Mon Sep 19 2022 - 12:27:43 EST


On Mon, Sep 19, 2022 at 12:42 PM Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
>
> Hi,
>
> On 9/12/22 13:53, Armin Wolf wrote:
> > Currently, battery hooks are being unloaded if they return
> > an error when adding a single battery.
> > This however also causes the removal of successfully added
> > hooks if they return -ENODEV for a single unsupported
> > battery.
> >
> > Do not unload battery hooks in such cases since the hook
> > handles any cleanup actions.
> >
> > Signed-off-by: Armin Wolf <W_Armin@xxxxxx>
>
> Maybe instead of removing all error checking, allow -ENODEV
> and behave as before when the error is not -ENODEV ?
>
> Otherwise we should probably make the add / remove callbacks
> void to indicate that any errors are ignored.
>
> Rafael, do you have any opinion on this?

IMV this is not a completely safe change, because things may simply
not work in the cases in which an error is returned.

It would be somewhat better to use a special error code to indicate
"no support" (eg. -ENOTSUPP) and ignore that one only.

> > ---
> > drivers/acpi/battery.c | 24 +++---------------------
> > 1 file changed, 3 insertions(+), 21 deletions(-)
> >
> > diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
> > index 306513fec1e1..e59c261c7c59 100644
> > --- a/drivers/acpi/battery.c
> > +++ b/drivers/acpi/battery.c
> > @@ -724,20 +724,10 @@ void battery_hook_register(struct acpi_battery_hook *hook)
> > * its attributes.
> > */
> > list_for_each_entry(battery, &acpi_battery_list, list) {
> > - if (hook->add_battery(battery->bat)) {
> > - /*
> > - * If a add-battery returns non-zero,
> > - * the registration of the extension has failed,
> > - * and we will not add it to the list of loaded
> > - * hooks.
> > - */
> > - pr_err("extension failed to load: %s", hook->name);
> > - __battery_hook_unregister(hook, 0);
> > - goto end;
> > - }
> > + hook->add_battery(battery->bat);
> > }
> > pr_info("new extension: %s\n", hook->name);
> > -end:
> > +
> > mutex_unlock(&hook_mutex);
> > }
> > EXPORT_SYMBOL_GPL(battery_hook_register);
> > @@ -762,15 +752,7 @@ static void battery_hook_add_battery(struct acpi_battery *battery)
> > * during the battery module initialization.
> > */
> > list_for_each_entry_safe(hook_node, tmp, &battery_hook_list, list) {
> > - if (hook_node->add_battery(battery->bat)) {
> > - /*
> > - * The notification of the extensions has failed, to
> > - * prevent further errors we will unload the extension.
> > - */
> > - pr_err("error in extension, unloading: %s",
> > - hook_node->name);
> > - __battery_hook_unregister(hook_node, 0);
> > - }
> > + hook_node->add_battery(battery->bat);
> > }
> > mutex_unlock(&hook_mutex);
> > }
> > --
> > 2.30.2
> >
>