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

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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,
> > 




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