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-rw-r--r--include/linux/sysfs.h142
1 files changed, 130 insertions, 12 deletions
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index b717a70219f6..326341c62385 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -61,22 +61,32 @@ do { \
/**
* struct attribute_group - data structure used to declare an attribute group.
* @name: Optional: Attribute group name
- * If specified, the attribute group will be created in
- * a new subdirectory with this name.
+ * If specified, the attribute group will be created in a
+ * new subdirectory with this name. Additionally when a
+ * group is named, @is_visible and @is_bin_visible may
+ * return SYSFS_GROUP_INVISIBLE to control visibility of
+ * the directory itself.
* @is_visible: Optional: Function to return permissions associated with an
- * attribute of the group. Will be called repeatedly for each
- * non-binary attribute in the group. Only read/write
+ * attribute of the group. Will be called repeatedly for
+ * each non-binary attribute in the group. Only read/write
* permissions as well as SYSFS_PREALLOC are accepted. Must
- * return 0 if an attribute is not visible. The returned value
- * will replace static permissions defined in struct attribute.
+ * return 0 if an attribute is not visible. The returned
+ * value will replace static permissions defined in struct
+ * attribute. Use SYSFS_GROUP_VISIBLE() when assigning this
+ * callback to specify separate _group_visible() and
+ * _attr_visible() handlers.
* @is_bin_visible:
* Optional: Function to return permissions associated with a
* binary attribute of the group. Will be called repeatedly
* for each binary attribute in the group. Only read/write
- * permissions as well as SYSFS_PREALLOC are accepted. Must
- * return 0 if a binary attribute is not visible. The returned
- * value will replace static permissions defined in
- * struct bin_attribute.
+ * permissions as well as SYSFS_PREALLOC (and the
+ * visibility flags for named groups) are accepted. Must
+ * return 0 if a binary attribute is not visible. The
+ * returned value will replace static permissions defined
+ * in struct bin_attribute. If @is_visible is not set, Use
+ * SYSFS_GROUP_VISIBLE() when assigning this callback to
+ * specify separate _group_visible() and _attr_visible()
+ * handlers.
* @attrs: Pointer to NULL terminated list of attributes.
* @bin_attrs: Pointer to NULL terminated list of binary attributes.
* Either attrs or bin_attrs or both must be provided.
@@ -91,13 +101,121 @@ struct attribute_group {
struct bin_attribute **bin_attrs;
};
+#define SYSFS_PREALLOC 010000
+#define SYSFS_GROUP_INVISIBLE 020000
+
+/*
+ * DEFINE_SYSFS_GROUP_VISIBLE(name):
+ * A helper macro to pair with the assignment of ".is_visible =
+ * SYSFS_GROUP_VISIBLE(name)", that arranges for the directory
+ * associated with a named attribute_group to optionally be hidden.
+ * This allows for static declaration of attribute_groups, and the
+ * simplification of attribute visibility lifetime that implies,
+ * without polluting sysfs with empty attribute directories.
+ * Ex.
+ *
+ * static umode_t example_attr_visible(struct kobject *kobj,
+ * struct attribute *attr, int n)
+ * {
+ * if (example_attr_condition)
+ * return 0;
+ * else if (ro_attr_condition)
+ * return 0444;
+ * return a->mode;
+ * }
+ *
+ * static bool example_group_visible(struct kobject *kobj)
+ * {
+ * if (example_group_condition)
+ * return false;
+ * return true;
+ * }
+ *
+ * DEFINE_SYSFS_GROUP_VISIBLE(example);
+ *
+ * static struct attribute_group example_group = {
+ * .name = "example",
+ * .is_visible = SYSFS_GROUP_VISIBLE(example),
+ * .attrs = &example_attrs,
+ * };
+ *
+ * Note that it expects <name>_attr_visible and <name>_group_visible to
+ * be defined. For cases where individual attributes do not need
+ * separate visibility consideration, only entire group visibility at
+ * once, see DEFINE_SIMPLE_SYSFS_GROUP_VISIBLE().
+ */
+#define DEFINE_SYSFS_GROUP_VISIBLE(name) \
+ static inline umode_t sysfs_group_visible_##name( \
+ struct kobject *kobj, struct attribute *attr, int n) \
+ { \
+ if (n == 0 && !name##_group_visible(kobj)) \
+ return SYSFS_GROUP_INVISIBLE; \
+ return name##_attr_visible(kobj, attr, n); \
+ }
+
+/*
+ * DEFINE_SIMPLE_SYSFS_GROUP_VISIBLE(name):
+ * A helper macro to pair with SYSFS_GROUP_VISIBLE() that like
+ * DEFINE_SYSFS_GROUP_VISIBLE() controls group visibility, but does
+ * not require the implementation of a per-attribute visibility
+ * callback.
+ * Ex.
+ *
+ * static bool example_group_visible(struct kobject *kobj)
+ * {
+ * if (example_group_condition)
+ * return false;
+ * return true;
+ * }
+ *
+ * DEFINE_SIMPLE_SYSFS_GROUP_VISIBLE(example);
+ *
+ * static struct attribute_group example_group = {
+ * .name = "example",
+ * .is_visible = SYSFS_GROUP_VISIBLE(example),
+ * .attrs = &example_attrs,
+ * };
+ */
+#define DEFINE_SIMPLE_SYSFS_GROUP_VISIBLE(name) \
+ static inline umode_t sysfs_group_visible_##name( \
+ struct kobject *kobj, struct attribute *a, int n) \
+ { \
+ if (n == 0 && !name##_group_visible(kobj)) \
+ return SYSFS_GROUP_INVISIBLE; \
+ return a->mode; \
+ }
+
+/*
+ * Same as DEFINE_SYSFS_GROUP_VISIBLE, but for groups with only binary
+ * attributes. If an attribute_group defines both text and binary
+ * attributes, the group visibility is determined by the function
+ * specified to is_visible() not is_bin_visible()
+ */
+#define DEFINE_SYSFS_BIN_GROUP_VISIBLE(name) \
+ static inline umode_t sysfs_group_visible_##name( \
+ struct kobject *kobj, struct bin_attribute *attr, int n) \
+ { \
+ if (n == 0 && !name##_group_visible(kobj)) \
+ return SYSFS_GROUP_INVISIBLE; \
+ return name##_attr_visible(kobj, attr, n); \
+ }
+
+#define DEFINE_SIMPLE_SYSFS_BIN_GROUP_VISIBLE(name) \
+ static inline umode_t sysfs_group_visible_##name( \
+ struct kobject *kobj, struct bin_attribute *a, int n) \
+ { \
+ if (n == 0 && !name##_group_visible(kobj)) \
+ return SYSFS_GROUP_INVISIBLE; \
+ return a->mode; \
+ }
+
+#define SYSFS_GROUP_VISIBLE(fn) sysfs_group_visible_##fn
+
/*
* Use these macros to make defining attributes easier.
* See include/linux/device.h for examples..
*/
-#define SYSFS_PREALLOC 010000
-
#define __ATTR(_name, _mode, _show, _store) { \
.attr = {.name = __stringify(_name), \
.mode = VERIFY_OCTAL_PERMISSIONS(_mode) }, \