Re: [Patch -mm 2/5] driver core: Introduce device_move(): move a device to a new parent.

[Cornelia Huck <cornelia.huck@de.ibm.com>]

On Wed, 15 Nov 2006 10:31:59 +0100,
Kay Sievers <kay.sievers@vrfy.org> wrote:

> We need the old DEVPATH in the environment (or something similar),
> otherwise we can't connect the event with the new device location to the
> current device. :)

Duh. I've attached another completely untested patch below.

> > Wouldn't we need something similar for kobject_rename()
> > as well?
> 
> Maybe kobject_rename() can go, if we have a move function which can be
> used. In any case, the events should look identical to userspace, yes.

I think kobject_move() and kobject_rename() are two different beasts.
kobject_move() changes the topology, kobject_rename() changes an
identifier. Shouldn't they be reported in two different ways to
userspace?

---
 include/linux/kobject.h |    6 ++++++
 lib/kobject.c           |   13 +++++++++++++
 lib/kobject_uevent.c    |   38 ++++++++++++++++++++++++++++++--------
 3 files changed, 49 insertions(+), 8 deletions(-)

--- linux-2.6-CH.orig/include/linux/kobject.h
+++ linux-2.6-CH/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 {
@@ -265,6 +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_extended(struct kobject *kobj, enum kobject_action action,
+			     const char *string);
 
 int add_uevent_var(char **envp, int num_envp, int *cur_index,
 			char *buffer, int buffer_size, int *cur_len,
@@ -272,6 +275,9 @@ 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_extended(struct kobject *kobj,
+					   enum kobject_action action,
+					   const char *string) { }
 
 static inline int add_uevent_var(char **envp, int num_envp, int *cur_index,
 				      char *buffer, int buffer_size, int *cur_len, 
--- linux-2.6-CH.orig/lib/kobject.c
+++ linux-2.6-CH/lib/kobject.c
@@ -364,6 +364,8 @@ int kobject_move(struct kobject *kobj, s
 {
 	int error;
 	struct kobject *old_parent;
+	const char *devpath = NULL;
+	const char *devpath_string = NULL;
 
 	kobj = kobject_get(kobj);
 	if (!kobj)
@@ -373,14 +375,25 @@ int kobject_move(struct kobject *kobj, s
 		error = -EINVAL;
 		goto out;
 	}
+	/* old object path */
+	devpath = kobject_get_path(kobj, GFP_KERNEL);
+	if (!devpath)
+		goto out;
+	devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
+	if (!devpath_string)
+		goto out;
+	sprintf(devpath_string, "OLD_DEVPATH=%s", devpath);
 	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_extended(kobj, KOBJ_MOVE, devpath);
 out:
 	kobject_put(kobj);
+	kfree(devpath_string);
+	kfree(devpath);
 	return error;
 }
 
--- linux-2.6-CH.orig/lib/kobject_uevent.c
+++ linux-2.6-CH/lib/kobject_uevent.c
@@ -55,13 +55,8 @@ static char *action_to_string(enum kobje
 	}
 }
 
-/**
- * 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)
+static void do_kobject_uevent(struct kobject *kobj, enum kobject_action action,
+			      const char *string)
 {
 	char **envp;
 	char *buffer;
@@ -134,7 +129,10 @@ void kobject_uevent(struct kobject *kobj
 	scratch += sprintf (scratch, "DEVPATH=%s", devpath) + 1;
 	envp [i++] = scratch;
 	scratch += sprintf(scratch, "SUBSYSTEM=%s", subsystem) + 1;
-
+	if (string != NULL) {
+		envp [i++] = scratch;
+		scratch += sprintf(scratch, "%s", string) + 1;
+	}
 	/* just reserve the space, overwrite it after kset call has returned */
 	envp[i++] = seq_buff = scratch;
 	scratch += strlen("SEQNUM=18446744073709551616") + 1;
@@ -200,9 +198,33 @@ exit:
 	kfree(envp);
 	return;
 }
+
+/**
+ * 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)
+{
+	do_kobject_uevent(kobj, action, NULL);
+}
 EXPORT_SYMBOL_GPL(kobject_uevent);
 
 /**
+ * kobject_uevent_extended - send an uevent with extended data
+ *
+ * @action: action that is happening (usually KOBJ_MOVE)
+ * @kobj: struct kobject that the action is happening to
+ * @string: string containing additional data
+ */
+void kobject_uevent_extended(struct kobject *kobj, enum kobject_action action,
+			     const char *string)
+{
+	do_kobject_uevent(kobj, action, string);
+}
+
+/**
  * add_uevent_var - helper for creating event variables
  * @envp: Pointer to table of environment variables, as passed into
  * uevent() method.