linux-kernel - RE: [PATCH v5] Introduce support for Systems Management Driver over WMI for Dell Systems

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Message-ID: <CY4PR19MB125486920AE0C6CA105B973A850D0@CY4PR19MB1254.namprd19.prod.outlook.com>
Date:   Tue, 6 Oct 2020 08:46:05 +0000
From:   "Bharathi, Divya" <Divya.Bharathi@...l.com>
To:     Hans de Goede <hdegoede@...hat.com>,
        Divya Bharathi <divya27392@...il.com>,
        "dvhart@...radead.org" <dvhart@...radead.org>
CC:     LKML <linux-kernel@...r.kernel.org>,
        "platform-driver-x86@...r.kernel.org" 
        <platform-driver-x86@...r.kernel.org>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        mark gross <mgross@...ux.intel.com>,
        "Limonciello, Mario" <Mario.Limonciello@...l.com>,
        "Ksr, Prasanth" <Prasanth.Ksr@...l.com>
Subject: RE: [PATCH v5] Introduce support for Systems Management Driver over
 WMI for Dell Systems

Sorry for another mail on same patch. I missed to add one response on
previous comments 

<snip>

> > +/**
> > + * init_bios_attributes() - Initialize all attributes for a type
> > + * @attr_type: The attribute type to initialize
> > + * @guid: The WMI GUID associated with this type to initialize
> > + *
> > + * Initialiaze all 4 types of attributes enumeration, integer, string and
> password object.
> > + * Populates each attrbute typ's respective properties under sysfs files
> > + **/
> > +static int init_bios_attributes(int attr_type, const char *guid)
> > +{
> > +	struct kobject *attr_name_kobj; //individual attribute names
> > +	union acpi_object *obj = NULL;
> > +	union acpi_object *elements;
> > +	struct kset *tmp_set;
> > +
> > +	/* instance_id needs to be reset for each type GUID
> > +	 * also, instance IDs are unique within GUID but not across
> > +	 */
> > +	int instance_id = 0;
> > +	int retval = 0;
> > +
> > +	retval = alloc_attributes_data(attr_type);
> > +	if (retval)
> > +		return retval;
> > +	/* need to use specific instance_id and guid combination to get right
> data */
> > +	obj = get_wmiobj_pointer(instance_id, guid);
> > +	if (!obj)
> > +		return -ENODEV;
> > +	elements = obj->package.elements;
> > +
> > +	mutex_lock(&wmi_priv.mutex);
> > +	while (elements) {
> > +		/* sanity checking */
> > +		if (strlen(elements[ATTR_NAME].string.pointer) == 0) {
> > +			pr_debug("empty attribute found\n");
> > +			goto nextobj;
> > +		}
> > +		if (attr_type == PO)
> > +			tmp_set = wmi_priv.authentication_dir_kset;
> > +		else
> > +			tmp_set = wmi_priv.main_dir_kset;
> > +
> > +		if (kset_find_obj(tmp_set,
> elements[ATTR_NAME].string.pointer)) {
> > +			pr_debug("duplicate attribute name found - %s\n",
> > +				elements[ATTR_NAME].string.pointer);
> > +			goto nextobj;
> > +		}
> > +
> > +		/* build attribute */
> > +		attr_name_kobj = kzalloc(sizeof(*attr_name_kobj),
> GFP_KERNEL);
> > +		if (!attr_name_kobj)
> > +			goto err_attr_init;
> > +
> > +		attr_name_kobj->kset = tmp_set;
> > +
> > +		retval = kobject_init_and_add(attr_name_kobj,
> &attr_name_ktype, NULL, "%s",
> > +
> 	elements[ATTR_NAME].string.pointer);
> > +		if (retval) {
> > +			kobject_put(attr_name_kobj);
> > +			goto err_attr_init;
> > +		}
> > +
> > +		/* enumerate all of this attribute */
> > +		switch (attr_type) {
> > +		case ENUM:
> > +			retval = populate_enum_data(elements, instance_id,
> attr_name_kobj);
> > +			break;
> > +		case INT:
> > +			retval = populate_int_data(elements, instance_id,
> attr_name_kobj);
> > +			break;
> > +		case STR:
> > +			retval = populate_str_data(elements, instance_id,
> attr_name_kobj);
> > +			break;
> > +		case PO:
> > +			retval = populate_po_data(elements, instance_id,
> attr_name_kobj);
> > +			break;
> > +		default:
> > +			break;
> > +		}
> 
> The show functions don't take the mutex and can be called as soon as
> kobject_init_and_add() is called, so it would be better to first populate the
> data for the current instance_id and only then call kobject_init_and_add()
> 

Populate functions called here for each type of attribute uses
attribute_koject which helps in attribute group cleanup.

Regards,
Divya