Re: [RFC PATCH 05/21] alienware-wmi: Refactor rgb-zones sysfs group creation

From: Kurt Borja
Date: Thu Dec 05 2024 - 07:48:26 EST

On Thu, Dec 05, 2024 at 12:17:01PM +0200, Ilpo Järvinen wrote:
> On Wed, 4 Dec 2024, Kurt Borja wrote:
>
> > Define zone_attrs statically with the use of helper macros and
> > initialize the zone_attribute_group with driver's .dev_groups.
> >
> > This makes match_zone() no longer needed, so drop it.
> >
> > Signed-off-by: Kurt Borja <kuurtb@xxxxxxxxx>
> > ---
> > drivers/platform/x86/dell/alienware-wmi.c | 137 ++++++++++------------
> > 1 file changed, 60 insertions(+), 77 deletions(-)
> >
> > diff --git a/drivers/platform/x86/dell/alienware-wmi.c b/drivers/platform/x86/dell/alienware-wmi.c
> > index 78bbb4ef4526..fa7bbbb07b86 100644
> > --- a/drivers/platform/x86/dell/alienware-wmi.c
> > +++ b/drivers/platform/x86/dell/alienware-wmi.c
> > @@ -378,7 +378,6 @@ struct color_platform {
> >
> > struct platform_zone {
> > u8 location;
> > - struct device_attribute *attr;
> > struct color_platform colors;
> > };
> >
> > @@ -411,16 +410,10 @@ struct wmax_u32_args {
> > };
> >
> > static struct platform_device *platform_device;
> > -static struct device_attribute *zone_dev_attrs;
> > -static struct attribute **zone_attrs;
> > static struct platform_zone *zone_data;
> > static struct platform_profile_handler pp_handler;
> > static enum wmax_thermal_mode supported_thermal_profiles[PLATFORM_PROFILE_LAST];
> >
> > -static struct attribute_group zone_attribute_group = {
> > - .name = "rgb_zones",
> > -};
> > -
> > static u8 interface;
> > static u8 lighting_control_state;
> > static u8 global_brightness;
> > @@ -452,20 +445,6 @@ static int parse_rgb(const char *buf, struct color_platform *colors)
> > return 0;
> > }
> >
> > -static struct platform_zone *match_zone(struct device_attribute *attr)
> > -{
> > - u8 zone;
> > -
> > - for (zone = 0; zone < quirks->num_zones; zone++) {
> > - if ((struct device_attribute *)zone_data[zone].attr == attr) {
> > - pr_debug("alienware-wmi: matched zone location: %d\n",
> > - zone_data[zone].location);
> > - return &zone_data[zone];
> > - }
> > - }
> > - return NULL;
> > -}
> > -
> > /*
> > * Individual RGB zone control
> > */
> > @@ -510,12 +489,10 @@ static int alienware_update_led(struct platform_zone *zone)
> > }
> >
> > static ssize_t zone_show(struct device *dev, struct device_attribute *attr,
> > - char *buf)
> > + char *buf, u8 location)
> > {
> > struct platform_zone *target_zone;
> > - target_zone = match_zone(attr);
> > - if (target_zone == NULL)
> > - return sprintf(buf, "red: -1, green: -1, blue: -1\n");
> > + target_zone = &zone_data[location];
> > return sprintf(buf, "red: %d, green: %d, blue: %d\n",
> > target_zone->colors.red,
> > target_zone->colors.green, target_zone->colors.blue);
> > @@ -523,15 +500,11 @@ static ssize_t zone_show(struct device *dev, struct device_attribute *attr,
> > }
> >
> > static ssize_t zone_set(struct device *dev, struct device_attribute *attr,
> > - const char *buf, size_t count)
> > + const char *buf, size_t count, u8 location)
> > {
> > struct platform_zone *target_zone;
> > int ret;
> > - target_zone = match_zone(attr);
> > - if (target_zone == NULL) {
> > - pr_err("alienware-wmi: invalid target zone\n");
> > - return 1;
> > - }
> > + target_zone = &zone_data[location];
> > ret = parse_rgb(buf, &target_zone->colors);
> > if (ret)
> > return ret;
> > @@ -539,6 +512,32 @@ static ssize_t zone_set(struct device *dev, struct device_attribute *attr,
> > return ret ? ret : count;
> > }
> >
> > +#define ALIENWARE_ZONE_SHOW_FUNC(_num) \
> > + static ssize_t zone0##_num##_show(struct device *dev, \
> > + struct device_attribute *attr, \
> > + char *buf) \
> > + { \
> > + return zone_show(dev, attr, buf, _num); \
> > + }
> > +
> > +#define ALIENWARE_ZONE_STORE_FUNC(_num) \
> > + static ssize_t zone0##_num##_store(struct device *dev, \
> > + struct device_attribute *attr, \
> > + const char *buf, size_t count) \
> > + { \
> > + return zone_set(dev, attr, buf, count, _num); \
> > + }
> > +
> > +#define ALIENWARE_ZONE_ATTR(_num) \
> > + ALIENWARE_ZONE_SHOW_FUNC(_num) \
> > + ALIENWARE_ZONE_STORE_FUNC(_num) \
> > + static DEVICE_ATTR_RW(zone0##_num)
> > +
> > +ALIENWARE_ZONE_ATTR(0);
> > +ALIENWARE_ZONE_ATTR(1);
> > +ALIENWARE_ZONE_ATTR(2);
> > +ALIENWARE_ZONE_ATTR(3);
> > +
> > /*
> > * Lighting control state device attribute (Global)
> > */
> > @@ -577,6 +576,33 @@ static ssize_t lighting_control_state_store(struct device *dev,
> >
> > static DEVICE_ATTR_RW(lighting_control_state);
> >
> > +static umode_t zone_attr_visible(struct kobject *kobj,
> > + struct attribute *attr, int n)
> > +{
> > + return n < quirks->num_zones + 1 ? 0644 : 0;
> > +}
> > +
> > +static bool zone_group_visible(struct kobject *kobj)
> > +{
> > + return quirks->num_zones > 0;
> > +}
> > +DEFINE_SYSFS_GROUP_VISIBLE(zone);
> > +
> > +static struct attribute *zone_attrs[] = {
> > + &dev_attr_lighting_control_state.attr,
> > + &dev_attr_zone00.attr,
> > + &dev_attr_zone01.attr,
> > + &dev_attr_zone02.attr,
> > + &dev_attr_zone03.attr,
> > + NULL
> > +};
> > +
> > +static struct attribute_group zone_attribute_group = {
> > + .name = "rgb_zones",
> > + .is_visible = SYSFS_GROUP_VISIBLE(zone),
> > + .attrs = zone_attrs,
> > +};
> > +
> > /*
> > * LED Brightness (Global)
> > */
> > @@ -624,7 +650,6 @@ static struct led_classdev global_led = {
> > static int alienware_zone_init(struct platform_device *dev)
> > {
> > u8 zone;
> > - char *name;
> >
> > if (interface == WMAX) {
> > lighting_control_state = WMAX_RUNNING;
> > @@ -634,65 +659,22 @@ static int alienware_zone_init(struct platform_device *dev)
> > global_led.max_brightness = 0x0F;
> > global_brightness = global_led.max_brightness;
> >
> > - /*
> > - * - zone_dev_attrs num_zones + 1 is for individual zones and then
> > - * null terminated
> > - * - zone_attrs num_zones + 2 is for all attrs in zone_dev_attrs +
> > - * the lighting control + null terminated
> > - * - zone_data num_zones is for the distinct zones
> > - */
> > - zone_dev_attrs =
> > - kcalloc(quirks->num_zones + 1, sizeof(struct device_attribute),
> > - GFP_KERNEL);
> > - if (!zone_dev_attrs)
> > - return -ENOMEM;
> > -
> > - zone_attrs =
> > - kcalloc(quirks->num_zones + 2, sizeof(struct attribute *),
> > - GFP_KERNEL);
> > - if (!zone_attrs)
> > - return -ENOMEM;
> > -
> > zone_data =
> > kcalloc(quirks->num_zones, sizeof(struct platform_zone),
> > GFP_KERNEL);
> > if (!zone_data)
> > return -ENOMEM;
> >
> > - for (zone = 0; zone < quirks->num_zones; zone++) {
> > - name = kasprintf(GFP_KERNEL, "zone%02hhX", zone);
> > - if (name == NULL)
> > - return 1;
> > - sysfs_attr_init(&zone_dev_attrs[zone].attr);
> > - zone_dev_attrs[zone].attr.name = name;
> > - zone_dev_attrs[zone].attr.mode = 0644;
> > - zone_dev_attrs[zone].show = zone_show;
> > - zone_dev_attrs[zone].store = zone_set;
> > + for (zone = 0; zone < 4; zone++)
>
> You allocate quirks->num_zones entries to zone_data above but use a
> literal here?

I did this because quirks->num_zones controlls only visibility now. I
didn't feel comfortable leaving an out of bounds access on zone_show()
and zone_set() when they do `zone_data[location]`.

Still those out of bounds accesses are hidden from user-space (right?) and
alienware_wmi_init() is getting dropped anyway so I should just leave it
as zone < quirks->num_zones.

>
> --
> i.
>
>
> > zone_data[zone].location = zone;
> > - zone_attrs[zone] = &zone_dev_attrs[zone].attr;
> > - zone_data[zone].attr = &zone_dev_attrs[zone];
> > - }
> > - zone_attrs[quirks->num_zones] = &dev_attr_lighting_control_state.attr;
> > - zone_attribute_group.attrs = zone_attrs;
> > -
> > - led_classdev_register(&dev->dev, &global_led);
> >
> > - return sysfs_create_group(&dev->dev.kobj, &zone_attribute_group);
> > + return led_classdev_register(&dev->dev, &global_led);
> > }
> >
> > static void alienware_zone_exit(struct platform_device *dev)
> > {
> > - u8 zone;
> > -
> > - sysfs_remove_group(&dev->dev.kobj, &zone_attribute_group);
> > led_classdev_unregister(&global_led);
> > - if (zone_dev_attrs) {
> > - for (zone = 0; zone < quirks->num_zones; zone++)
> > - kfree(zone_dev_attrs[zone].attr.name);
> > - }
> > - kfree(zone_dev_attrs);
> > kfree(zone_data);
> > - kfree(zone_attrs);
> > }
> >
> > static acpi_status alienware_wmax_command(void *in_args, size_t in_size,
> > @@ -1140,6 +1122,7 @@ static void remove_thermal_profile(void)
> > * Platform Driver
> > */
> > static const struct attribute_group *alienfx_groups[] = {
> > + &zone_attribute_group,
> > &hdmi_attribute_group,
> > &amplifier_attribute_group,
> > &deepsleep_attribute_group,
> >