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Subject[PATCH 32/36] driver core: Introduce device_move(): move a device to a new parent.
Date
From: Cornelia Huck <cornelia.huck@de.ibm.com>

Provide a function device_move() to move a device to a new parent device. Add
auxilliary functions kobject_move() and sysfs_move_dir().
kobject_move() generates a new uevent of type KOBJ_MOVE, containing the
previous path (DEVPATH_OLD) in addition to the usual values. For this, a new
interface kobject_uevent_env() is created that allows to add further
environmental data to the uevent at the kobject layer.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Acked-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
drivers/base/core.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++
fs/sysfs/dir.c | 45 +++++++++++++++++++++++
include/linux/device.h | 1 +
include/linux/kobject.h | 8 ++++
include/linux/sysfs.h | 8 ++++
lib/kobject.c | 50 +++++++++++++++++++++++++
lib/kobject_uevent.c | 28 ++++++++++++--
7 files changed, 228 insertions(+), 4 deletions(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 75b45a1..e4eaf46 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -955,3 +955,95 @@ int device_rename(struct device *dev, ch

return error;
}
+
+
+static int device_move_class_links(struct device *dev,
+ struct device *old_parent,
+ struct device *new_parent)
+{
+#ifdef CONFIG_SYSFS_DEPRECATED
+ int error;
+ char *class_name;
+
+ class_name = make_class_name(dev->class->name, &dev->kobj);
+ if (!class_name) {
+ error = PTR_ERR(class_name);
+ class_name = NULL;
+ goto out;
+ }
+ if (old_parent) {
+ sysfs_remove_link(&dev->kobj, "device");
+ sysfs_remove_link(&old_parent->kobj, class_name);
+ }
+ error = sysfs_create_link(&dev->kobj, &new_parent->kobj, "device");
+ if (error)
+ goto out;
+ error = sysfs_create_link(&new_parent->kobj, &dev->kobj, class_name);
+ if (error)
+ sysfs_remove_link(&dev->kobj, "device");
+out:
+ kfree(class_name);
+ return error;
+#else
+ return 0;
+#endif
+}
+
+/**
+ * device_move - moves a device to a new parent
+ * @dev: the pointer to the struct device to be moved
+ * @new_parent: the new parent of the device
+ */
+int device_move(struct device *dev, struct device *new_parent)
+{
+ int error;
+ struct device *old_parent;
+
+ dev = get_device(dev);
+ if (!dev)
+ return -EINVAL;
+
+ if (!device_is_registered(dev)) {
+ error = -EINVAL;
+ goto out;
+ }
+ new_parent = get_device(new_parent);
+ if (!new_parent) {
+ error = -EINVAL;
+ goto out;
+ }
+ pr_debug("DEVICE: moving '%s' to '%s'\n", dev->bus_id,
+ new_parent->bus_id);
+ error = kobject_move(&dev->kobj, &new_parent->kobj);
+ if (error) {
+ put_device(new_parent);
+ goto out;
+ }
+ old_parent = dev->parent;
+ dev->parent = new_parent;
+ if (old_parent)
+ klist_del(&dev->knode_parent);
+ klist_add_tail(&dev->knode_parent, &new_parent->klist_children);
+ if (!dev->class)
+ goto out_put;
+ error = device_move_class_links(dev, old_parent, new_parent);
+ if (error) {
+ /* We ignore errors on cleanup since we're hosed anyway... */
+ device_move_class_links(dev, new_parent, old_parent);
+ if (!kobject_move(&dev->kobj, &old_parent->kobj)) {
+ klist_del(&dev->knode_parent);
+ if (old_parent)
+ klist_add_tail(&dev->knode_parent,
+ &old_parent->klist_children);
+ }
+ put_device(new_parent);
+ goto out;
+ }
+out_put:
+ put_device(old_parent);
+out:
+ put_device(dev);
+ return error;
+}
+
+EXPORT_SYMBOL_GPL(device_move);
diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 3aa3434..a5782e8 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -372,6 +372,51 @@ int sysfs_rename_dir(struct kobject * ko
return error;
}

+int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent)
+{
+ struct dentry *old_parent_dentry, *new_parent_dentry, *new_dentry;
+ struct sysfs_dirent *new_parent_sd, *sd;
+ int error;
+
+ if (!new_parent)
+ return -EINVAL;
+
+ old_parent_dentry = kobj->parent ?
+ kobj->parent->dentry : sysfs_mount->mnt_sb->s_root;
+ new_parent_dentry = new_parent->dentry;
+
+again:
+ mutex_lock(&old_parent_dentry->d_inode->i_mutex);
+ if (!mutex_trylock(&new_parent_dentry->d_inode->i_mutex)) {
+ mutex_unlock(&old_parent_dentry->d_inode->i_mutex);
+ goto again;
+ }
+
+ new_parent_sd = new_parent_dentry->d_fsdata;
+ sd = kobj->dentry->d_fsdata;
+
+ new_dentry = lookup_one_len(kobj->name, new_parent_dentry,
+ strlen(kobj->name));
+ if (IS_ERR(new_dentry)) {
+ error = PTR_ERR(new_dentry);
+ goto out;
+ } else
+ error = 0;
+ d_add(new_dentry, NULL);
+ d_move(kobj->dentry, new_dentry);
+ dput(new_dentry);
+
+ /* Remove from old parent's list and insert into new parent's list. */
+ list_del_init(&sd->s_sibling);
+ list_add(&sd->s_sibling, &new_parent_sd->s_children);
+
+out:
+ mutex_unlock(&new_parent_dentry->d_inode->i_mutex);
+ mutex_unlock(&old_parent_dentry->d_inode->i_mutex);
+
+ return error;
+}
+
static int sysfs_dir_open(struct inode *inode, struct file *file)
{
struct dentry * dentry = file->f_dentry;
diff --git a/include/linux/device.h b/include/linux/device.h
index 0a0370c..583a341 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -424,6 +424,7 @@ extern int device_for_each_child(struct
extern struct device *device_find_child(struct device *, void *data,
int (*match)(struct device *, void *));
extern int device_rename(struct device *dev, char *new_name);
+extern int device_move(struct device *dev, struct device *new_parent);

/*
* Manual binding of a device to driver. See drivers/base/bus.c
diff --git a/include/linux/kobject.h b/include/linux/kobject.h
index bcd9cd1..d1c8d28 100644
--- a/include/linux/kobject.h
+++ b/include/linux/kobject.h
@@ -47,6 +47,7 @@ enum kobject_action {
KOBJ_UMOUNT = (__force kobject_action_t) 0x05, /* umount event for block devices (broken) */
KOBJ_OFFLINE = (__force kobject_action_t) 0x06, /* device offline */
KOBJ_ONLINE = (__force kobject_action_t) 0x07, /* device online */
+ KOBJ_MOVE = (__force kobject_action_t) 0x08, /* device move */
};

struct kobject {
@@ -76,6 +77,7 @@ extern int __must_check kobject_add(stru
extern void kobject_del(struct kobject *);

extern int __must_check kobject_rename(struct kobject *, const char *new_name);
+extern int __must_check kobject_move(struct kobject *, struct kobject *);

extern int __must_check kobject_register(struct kobject *);
extern void kobject_unregister(struct kobject *);
@@ -264,6 +266,8 @@ extern int __must_check subsys_create_fi

#if defined(CONFIG_HOTPLUG)
void kobject_uevent(struct kobject *kobj, enum kobject_action action);
+void kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
+ char *envp[]);

int add_uevent_var(char **envp, int num_envp, int *cur_index,
char *buffer, int buffer_size, int *cur_len,
@@ -271,6 +275,10 @@ int add_uevent_var(char **envp, int num_
__attribute__((format (printf, 7, 8)));
#else
static inline void kobject_uevent(struct kobject *kobj, enum kobject_action action) { }
+static inline void kobject_uevent_env(struct kobject *kobj,
+ enum kobject_action action,
+ char *envp[])
+{ }

static inline int add_uevent_var(char **envp, int num_envp, int *cur_index,
char *buffer, int buffer_size, int *cur_len,
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 6d5c43d..2129d1b 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -97,6 +97,9 @@ extern int __must_check
sysfs_rename_dir(struct kobject *, const char *new_name);

extern int __must_check
+sysfs_move_dir(struct kobject *, struct kobject *);
+
+extern int __must_check
sysfs_create_file(struct kobject *, const struct attribute *);

extern int __must_check
@@ -142,6 +145,11 @@ static inline int sysfs_rename_dir(struc
return 0;
}

+static inline int sysfs_move_dir(struct kobject * k, struct kobject * new_parent)
+{
+ return 0;
+}
+
static inline int sysfs_create_file(struct kobject * k, const struct attribute * a)
{
return 0;
diff --git a/lib/kobject.c b/lib/kobject.c
index 7dd5c0e..744a4b1 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -311,6 +311,56 @@ int kobject_rename(struct kobject * kobj
}

/**
+ * kobject_move - move object to another parent
+ * @kobj: object in question.
+ * @new_parent: object's new parent
+ */
+
+int kobject_move(struct kobject *kobj, struct kobject *new_parent)
+{
+ int error;
+ struct kobject *old_parent;
+ const char *devpath = NULL;
+ char *devpath_string = NULL;
+ char *envp[2];
+
+ kobj = kobject_get(kobj);
+ if (!kobj)
+ return -EINVAL;
+ new_parent = kobject_get(new_parent);
+ if (!new_parent) {
+ error = -EINVAL;
+ goto out;
+ }
+ /* old object path */
+ devpath = kobject_get_path(kobj, GFP_KERNEL);
+ if (!devpath) {
+ error = -ENOMEM;
+ goto out;
+ }
+ devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
+ if (!devpath_string) {
+ error = -ENOMEM;
+ goto out;
+ }
+ sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
+ envp[0] = devpath_string;
+ envp[1] = NULL;
+ error = sysfs_move_dir(kobj, new_parent);
+ if (error)
+ goto out;
+ old_parent = kobj->parent;
+ kobj->parent = new_parent;
+ kobject_put(old_parent);
+ kobject_uevent_env(kobj, KOBJ_MOVE, envp);
+out:
+ kobject_put(kobj);
+ kfree(devpath_string);
+ kfree(devpath);
+ return error;
+}
+
+/**
* kobject_del - unlink kobject from hierarchy.
* @kobj: object.
*/
diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c
index 7f20e7b..a192276 100644
--- a/lib/kobject_uevent.c
+++ b/lib/kobject_uevent.c
@@ -50,18 +50,22 @@ static char *action_to_string(enum kobje
return "offline";
case KOBJ_ONLINE:
return "online";
+ case KOBJ_MOVE:
+ return "move";
default:
return NULL;
}
}

/**
- * kobject_uevent - notify userspace by ending an uevent
+ * kobject_uevent_env - send an uevent with environmental data
*
- * @action: action that is happening (usually KOBJ_ADD and KOBJ_REMOVE)
+ * @action: action that is happening (usually KOBJ_MOVE)
* @kobj: struct kobject that the action is happening to
+ * @envp_ext: pointer to environmental data
*/
-void kobject_uevent(struct kobject *kobj, enum kobject_action action)
+void kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
+ char *envp_ext[])
{
char **envp;
char *buffer;
@@ -76,6 +80,7 @@ void kobject_uevent(struct kobject *kobj
char *seq_buff;
int i = 0;
int retval;
+ int j;

pr_debug("%s\n", __FUNCTION__);

@@ -134,7 +139,8 @@ void kobject_uevent(struct kobject *kobj
scratch += sprintf (scratch, "DEVPATH=%s", devpath) + 1;
envp [i++] = scratch;
scratch += sprintf(scratch, "SUBSYSTEM=%s", subsystem) + 1;
-
+ for (j = 0; envp_ext && envp_ext[j]; j++)
+ envp[i++] = envp_ext[j];
/* just reserve the space, overwrite it after kset call has returned */
envp[i++] = seq_buff = scratch;
scratch += strlen("SEQNUM=18446744073709551616") + 1;
@@ -200,6 +206,20 @@ exit:
kfree(envp);
return;
}
+
+EXPORT_SYMBOL_GPL(kobject_uevent_env);
+
+/**
+ * kobject_uevent - notify userspace by ending an uevent
+ *
+ * @action: action that is happening (usually KOBJ_ADD and KOBJ_REMOVE)
+ * @kobj: struct kobject that the action is happening to
+ */
+void kobject_uevent(struct kobject *kobj, enum kobject_action action)
+{
+ kobject_uevent_env(kobj, action, NULL);
+}
+
EXPORT_SYMBOL_GPL(kobject_uevent);

/**
--
1.4.4.1
-
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