Commit 2d76fdc1 authored by Thomas Weißschuh's avatar Thomas Weißschuh Committed by Greg Kroah-Hartman
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samples/kobject: constify 'struct foo_attribute'



Showcase and test the new 'struct attribute' constification facilities.

Signed-off-by: default avatarThomas Weißschuh <linux@weissschuh.net>
Link: https://patch.msgid.link/20251029-sysfs-const-attr-prep-v5-6-ea7d745acff4@weissschuh.net


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c301a2e2
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+17 −16
Original line number Diff line number Diff line
@@ -37,10 +37,11 @@ struct foo_obj {
/* a custom attribute that works just for a struct foo_obj. */
struct foo_attribute {
	struct attribute attr;
	ssize_t (*show)(struct foo_obj *foo, struct foo_attribute *attr, char *buf);
	ssize_t (*store)(struct foo_obj *foo, struct foo_attribute *attr, const char *buf, size_t count);
	ssize_t (*show)(struct foo_obj *foo, const struct foo_attribute *attr, char *buf);
	ssize_t (*store)(struct foo_obj *foo, const struct foo_attribute *attr,
			 const char *buf, size_t count);
};
#define to_foo_attr(x) container_of(x, struct foo_attribute, attr)
#define to_foo_attr(x) container_of_const(x, struct foo_attribute, attr)

/*
 * The default show function that must be passed to sysfs.  This will be
@@ -53,7 +54,7 @@ static ssize_t foo_attr_show(struct kobject *kobj,
			     struct attribute *attr,
			     char *buf)
{
	struct foo_attribute *attribute;
	const struct foo_attribute *attribute;
	struct foo_obj *foo;

	attribute = to_foo_attr(attr);
@@ -73,7 +74,7 @@ static ssize_t foo_attr_store(struct kobject *kobj,
			      struct attribute *attr,
			      const char *buf, size_t len)
{
	struct foo_attribute *attribute;
	const struct foo_attribute *attribute;
	struct foo_obj *foo;

	attribute = to_foo_attr(attr);
@@ -109,13 +110,13 @@ static void foo_release(struct kobject *kobj)
/*
 * The "foo" file where the .foo variable is read from and written to.
 */
static ssize_t foo_show(struct foo_obj *foo_obj, struct foo_attribute *attr,
static ssize_t foo_show(struct foo_obj *foo_obj, const struct foo_attribute *attr,
			char *buf)
{
	return sysfs_emit(buf, "%d\n", foo_obj->foo);
}

static ssize_t foo_store(struct foo_obj *foo_obj, struct foo_attribute *attr,
static ssize_t foo_store(struct foo_obj *foo_obj, const struct foo_attribute *attr,
			 const char *buf, size_t count)
{
	int ret;
@@ -128,14 +129,14 @@ static ssize_t foo_store(struct foo_obj *foo_obj, struct foo_attribute *attr,
}

/* Sysfs attributes cannot be world-writable. */
static struct foo_attribute foo_attribute =
static const struct foo_attribute foo_attribute =
	__ATTR(foo, 0664, foo_show, foo_store);

/*
 * More complex function where we determine which variable is being accessed by
 * looking at the attribute for the "baz" and "bar" files.
 */
static ssize_t b_show(struct foo_obj *foo_obj, struct foo_attribute *attr,
static ssize_t b_show(struct foo_obj *foo_obj, const struct foo_attribute *attr,
		      char *buf)
{
	int var;
@@ -147,7 +148,7 @@ static ssize_t b_show(struct foo_obj *foo_obj, struct foo_attribute *attr,
	return sysfs_emit(buf, "%d\n", var);
}

static ssize_t b_store(struct foo_obj *foo_obj, struct foo_attribute *attr,
static ssize_t b_store(struct foo_obj *foo_obj, const struct foo_attribute *attr,
		       const char *buf, size_t count)
{
	int var, ret;
@@ -163,16 +164,16 @@ static ssize_t b_store(struct foo_obj *foo_obj, struct foo_attribute *attr,
	return count;
}

static struct foo_attribute baz_attribute =
static const struct foo_attribute baz_attribute =
	__ATTR(baz, 0664, b_show, b_store);
static struct foo_attribute bar_attribute =
static const struct foo_attribute bar_attribute =
	__ATTR(bar, 0664, b_show, b_store);

/*
 * Create a group of attributes so that we can create and destroy them all
 * at once.
 */
static struct attribute *foo_default_attrs[] = {
static const struct attribute *const foo_default_attrs[] = {
	&foo_attribute.attr,
	&baz_attribute.attr,
	&bar_attribute.attr,
@@ -180,7 +181,7 @@ static struct attribute *foo_default_attrs[] = {
};

static umode_t foo_default_attrs_is_visible(struct kobject *kobj,
					    struct attribute *attr,
					    const struct attribute *attr,
					    int n)
{
	/* Hide attributes with the same name as the kobject. */
@@ -190,8 +191,8 @@ static umode_t foo_default_attrs_is_visible(struct kobject *kobj,
}

static const struct attribute_group foo_default_group = {
	.attrs		= foo_default_attrs,
	.is_visible	= foo_default_attrs_is_visible,
	.attrs_const		= foo_default_attrs,
	.is_visible_const	= foo_default_attrs_is_visible,
};
__ATTRIBUTE_GROUPS(foo_default);