[PATCH v4 2/6] sysfs: wrap __compat_only_sysfs_link_entry_to_kobj function to change the symlink name

Sourabh Jain
2019-12-06T12:24:55Z

The __compat_only_sysfs_link_entry_to_kobj function creates a symlink to a
kobject but doesn't provide an option to change the symlink file name.

This patch adds a wrapper function create_sysfs_symlink_entry_to_kobj that
extends the __compat_only_sysfs_link_entry_to_kobj functionality which
allows function caller to customize the symlink name.

Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
---
fs/sysfs/group.c | 28 +++++++++++++++++++++++++---
include/linux/sysfs.h | 12 ++++++++++++
2 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
index d41c21fef138..5eb38145b957 100644
--- a/fs/sysfs/group.c
+++ b/fs/sysfs/group.c
@@ -424,6 +424,25 @@ EXPORT_SYMBOL_GPL(sysfs_remove_link_from_group);
int __compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
struct kobject *target_kobj,
const char *target_name)
+{
+ return create_sysfs_symlink_entry_to_kobj(kobj, target_kobj,
+ target_name, NULL);
+}
+EXPORT_SYMBOL_GPL(__compat_only_sysfs_link_entry_to_kobj);
+
+/**
+ * create_sysfs_symlink_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.
+ * @symlink_name: The name of the symlink file (target_name will be
+ * considered if symlink_name is NULL).
+ */
+int create_sysfs_symlink_entry_to_kobj(struct kobject *kobj,
+ struct kobject *target_kobj,
+ const char *target_name,
+ const char *symlink_name)
{
struct kernfs_node *target;
struct kernfs_node *entry;
@@ -448,12 +467,15 @@ int __compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
return -ENOENT;
}

- link = kernfs_create_link(kobj->sd, target_name, entry);
+ if (!symlink_name)
+ symlink_name = target_name;
+
+ link = kernfs_create_link(kobj->sd, symlink_name, entry);
if (IS_ERR(link) && PTR_ERR(link) == -EEXIST)
- sysfs_warn_dup(kobj->sd, target_name);
+ sysfs_warn_dup(kobj->sd, symlink_name);

kernfs_put(entry);
kernfs_put(target);
return PTR_ERR_OR_ZERO(link);
}
-EXPORT_SYMBOL_GPL(__compat_only_sysfs_link_entry_to_kobj);
+EXPORT_SYMBOL_GPL(create_sysfs_symlink_entry_to_kobj);
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 5420817ed317..123c6f10333a 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -300,6 +300,10 @@ void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
int __compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
struct kobject *target_kobj,
const char *target_name);
+int create_sysfs_symlink_entry_to_kobj(struct kobject *kobj,
+ struct kobject *target_kobj,
+ const char *target_name,
+ const char *symlink_name);

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

@@ -508,6 +512,14 @@ static inline int __compat_only_sysfs_link_entry_to_kobj(
return 0;
}

+static int create_sysfs_symlink_entry_to_kobj(struct kobject *kobj,
+ struct kobject *target_kobj,
+ const char *target_name,
+ const char *symlink_name)
+{
+ return 0;
+}
+
static inline void sysfs_notify(struct kobject *kobj, const char *dir,
const char *attr)
{
--
2.17.2