/**
* sysfs_remove_dir - remove an object's directory.
* @kobj: object.
*
* The only thing special about this is that we remove any files in
* the directory before we remove the directory, and we've inlined
* what used to be sysfs_rmdir() below, instead of calling separately.
*/
void sysfs_remove_dir(struct kobject *kobj)
{
struct kernfs_node *kn = kobj->sd;
/*
* In general, kboject owner is responsible for ensuring removal
* doesn't race with other operations and sysfs doesn't provide any
* protection; however, when @kobj is used as a symlink target, the
* symlinking entity usually doesn't own @kobj and thus has no
* control over removal. @kobj->sd may be removed anytime
* and symlink code may end up dereferencing an already freed node.
*
* sysfs_symlink_target_lock synchronizes @kobj->sd
* disassociation against symlink operations so that symlink code
* can safely dereference @kobj->sd.
*/
spin_lock(&sysfs_symlink_target_lock);
kobj->sd = NULL;
spin_unlock(&sysfs_symlink_target_lock);
if (kn) {
WARN_ON_ONCE(kernfs_type(kn) != KERNFS_DIR);
kernfs_remove(kn);
}
}
/**
* sysfs_remove_group: remove a group from a kobject
* @kobj: kobject to remove the group from
* @grp: group to remove
*
* This function removes a group of attributes from a kobject. The attributes
* previously have to have been created for this group, otherwise it will fail.
*/
void sysfs_remove_group(struct kobject *kobj,
const struct attribute_group *grp)
{
struct kernfs_node *parent = kobj->sd;
struct kernfs_node *kn;
if (grp->name) {
kn = kernfs_find_and_get(parent, grp->name);
if (!kn) {
WARN(!kn, KERN_WARNING
"sysfs group %p not found for kobject '%s'\n",
grp, kobject_name(kobj));
return;
}
} else {
kn = parent;
kernfs_get(kn);
}
remove_files(kn, kobj, grp);
if (grp->name)
kernfs_remove(kn);
kernfs_put(kn);
}
static int internal_create_group(struct kobject *kobj, int update,
const struct attribute_group *grp)
{
struct kernfs_node *kn;
int error;
BUG_ON(!kobj || (!update && !kobj->sd));
/* Updates may happen before the object has been instantiated */
if (unlikely(update && !kobj->sd))
return -EINVAL;
if (!grp->attrs && !grp->bin_attrs) {
WARN(1, "sysfs: (bin_)attrs not set by subsystem for group: %s/%s\n",
kobj->name, grp->name ? "" : grp->name);
return -EINVAL;
}
if (grp->name) {
kn = kernfs_create_dir(kobj->sd, grp->name,
S_IRWXU | S_IRUGO | S_IXUGO, kobj);
if (IS_ERR(kn)) {
if (PTR_ERR(kn) == -EEXIST)
sysfs_warn_dup(kobj->sd, grp->name);
return PTR_ERR(kn);
}
} else
kn = kobj->sd;
kernfs_get(kn);
error = create_files(kn, kobj, grp, update);
if (error) {
if (grp->name)
kernfs_remove(kn);
}
kernfs_put(kn);
return error;
}
static int dslab_rmdir(struct kernfs_node *kn)
{
kernfs_break_active_protection(kn);
kernfs_remove(kn);
kernfs_unbreak_active_protection(kn);
return 0;
}
/*! 2017. 1.07 study -ing */
void kernfs_destroy_root(struct kernfs_root *root)
{
kernfs_remove(root->kn); /* will also free @root */
}