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Subject[PATCH v3 1/2] sysfs: added sysfs_link_entry_to_kobj()
Date
Added a new function sysfs_link_group_to_kobj() that adds a symlink
from attribute or group to a kobject. Exported kernfs_remove_by_name_ns
in order to provide a way to remove such symlinks.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
fs/kernfs/dir.c | 1 +
fs/sysfs/group.c | 42 ++++++++++++++++++++++++++++++++++++++++++
include/linux/sysfs.h | 8 ++++++++
3 files changed, 51 insertions(+)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 6acc964..749cea3 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -1225,6 +1225,7 @@ int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name,
else
return -ENOENT;
}
+EXPORT_SYMBOL_GPL(kernfs_remove_by_name_ns);

/**
* kernfs_rename_ns - move and rename a kernfs_node
diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
index b400c04..5c72996 100644
--- a/fs/sysfs/group.c
+++ b/fs/sysfs/group.c
@@ -352,3 +352,45 @@ void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
}
}
EXPORT_SYMBOL_GPL(sysfs_remove_link_from_group);
+
+/**
+ * sysfs_link_entry_to_kobj - add a symlink to a kobject pointing to a group or an attribute
+ * @kobj: The kobject containing the group.
+ * @target_kobj: The target kobject.
+ * @target_name: The name of the target group or attribute.
+ */
+int sysfs_link_entry_to_kobj(struct kobject *kobj, struct kobject *target_kobj,
+ const char *target_name)
+{
+ struct kernfs_node *target;
+ struct kernfs_node *entry;
+ struct kernfs_node *link;
+
+ /*
+ * We don't own @target_kobj and it may be removed at any time.
+ * Synchronize using sysfs_symlink_target_lock. See sysfs_remove_dir()
+ * for details.
+ */
+ spin_lock(&sysfs_symlink_target_lock);
+ target = target_kobj->sd;
+ if (target)
+ kernfs_get(target);
+ spin_unlock(&sysfs_symlink_target_lock);
+ if (!target)
+ return -ENOENT;
+
+ entry = kernfs_find_and_get(target_kobj->sd, target_name);
+ if (!entry) {
+ kernfs_put(target);
+ return -ENOENT;
+ }
+
+ link = kernfs_create_link(kobj->sd, target_name, entry);
+ if (IS_ERR(link) && PTR_ERR(link) == -EEXIST)
+ sysfs_warn_dup(kobj->sd, target_name);
+
+ kernfs_put(entry);
+ kernfs_put(target);
+ return IS_ERR(link) ? PTR_ERR(link) : 0;
+}
+EXPORT_SYMBOL_GPL(sysfs_link_entry_to_kobj);
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 99382c0..f2be044 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -264,6 +264,8 @@ int sysfs_add_link_to_group(struct kobject *kobj, const char *group_name,
struct kobject *target, const char *link_name);
void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
const char *link_name);
+int sysfs_link_entry_to_kobj(struct kobject *kobj, struct kobject *target_kobj,
+ const char *target_name);

void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr);

@@ -436,6 +438,12 @@ static inline void sysfs_remove_link_from_group(struct kobject *kobj,
{
}

+int sysfs_link_entry_to_kobj(struct kobject *kobj, struct kobject *target_kobj,
+ const char *target_name)
+{
+ return 0;
+}
+
static inline void sysfs_notify(struct kobject *kobj, const char *dir,
const char *attr)
{
--
2.1.4


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