[RFC/Patch 1/5] driver core: Introduce device_find_child().

[RFC/Patch 1/5] driver core: Introduce device_find_child().

[Cornelia Huck]

From: Cornelia Huck <cornelia.huck@de.ibm.com>

Introduce device_find_child() to match device_for_each_child().

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

---
 drivers/base/core.c    |   32 ++++++++++++++++++++++++++++++++
 include/linux/device.h |    2 ++
 2 files changed, 34 insertions(+)

--- linux-2.6-CH.orig/drivers/base/core.c
+++ linux-2.6-CH/drivers/base/core.c
@@ -749,12 +749,44 @@ int device_for_each_child(struct device 
 	return error;
 }
 
+/**
+ * device_find_child - device iterator for locating a particular device.
+ * @parent: parent struct device
+ * @data: Data to pass to match function
+ * @match: Callback function to check device
+ *
+ * This is similar to the device_for_each_child() function above, but it
+ * returns a reference to a device that is 'found' for later use, as
+ * determined by the @match callback.
+ *
+ * The callback should return 0 if the device doesn't match and non-zero
+ * if it does.  If the callback returns non-zero, this function will
+ * return to the caller and not iterate over any more devices.
+ */
+struct device * device_find_child(struct device *parent, void *data,
+				  int (*match)(struct device *, void *))
+{
+	struct klist_iter i;
+	struct device *child;
+
+	if (!parent)
+		return NULL;
+
+	klist_iter_init(&parent->klist_children, &i);
+	while ((child = next_device(&i)))
+		if (match(child, data) && get_device(child))
+			break;
+	klist_iter_exit(&i);
+	return child;
+}
+
 int __init devices_init(void)
 {
 	return subsystem_register(&devices_subsys);
 }
 
 EXPORT_SYMBOL_GPL(device_for_each_child);
+EXPORT_SYMBOL_GPL(device_find_child);
 
 EXPORT_SYMBOL_GPL(device_initialize);
 EXPORT_SYMBOL_GPL(device_add);
--- linux-2.6-CH.orig/include/linux/device.h
+++ linux-2.6-CH/include/linux/device.h
@@ -420,6 +420,8 @@ extern int __must_check device_add(struc
 extern void device_del(struct device * dev);
 extern int device_for_each_child(struct device *, void *,
 		     int (*fn)(struct device *, void *));
+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);
 
 /*

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

[Cornelia Huck]

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().

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

---
 drivers/base/core.c     |   92 ++++++++++++++++++++++++++++++++++++++++++++++++
 fs/sysfs/dir.c          |   45 +++++++++++++++++++++++
 include/linux/device.h  |    1 
 include/linux/kobject.h |    1 
 include/linux/sysfs.h   |    3 +
 lib/kobject.c           |   30 +++++++++++++++
 6 files changed, 172 insertions(+)

--- linux-2.6-CH.orig/drivers/base/core.c
+++ linux-2.6-CH/drivers/base/core.c
@@ -953,3 +953,95 @@ 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);
--- linux-2.6-CH.orig/fs/sysfs/dir.c
+++ linux-2.6-CH/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_path.dentry;
--- linux-2.6-CH.orig/include/linux/device.h
+++ linux-2.6-CH/include/linux/device.h
@@ -423,6 +423,7 @@ 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
--- linux-2.6-CH.orig/include/linux/kobject.h
+++ linux-2.6-CH/include/linux/kobject.h
@@ -76,6 +76,7 @@ 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 *);
--- linux-2.6-CH.orig/include/linux/sysfs.h
+++ linux-2.6-CH/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
--- linux-2.6-CH.orig/lib/kobject.c
+++ linux-2.6-CH/lib/kobject.c
@@ -355,6 +355,36 @@ 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;
+
+	kobj = kobject_get(kobj);
+	if (!kobj)
+		return -EINVAL;
+	new_parent = kobject_get(new_parent);
+	if (!new_parent) {
+		error = -EINVAL;
+		goto out;
+	}
+	error = sysfs_move_dir(kobj, new_parent);
+	if (error)
+		goto out;
+	old_parent = kobj->parent;
+	kobj->parent = new_parent;
+	kobject_put(old_parent);
+out:
+	kobject_put(kobj);
+	return error;
+}
+
+/**
  *	kobject_del - unlink kobject from hierarchy.
  * 	@kobj:	object.
  */

[RFC/Patch 3/5] s390: Prepatory cleanup in common I/O layer.

[Cornelia Huck]

From: Cornelia Huck <cornelia.huck@de.ibm.com>

Some preparations for the dynamic subchannel mapping patch.

- Move adding subchannel attributes to css_register_subchannel().
- Don't call device_trigger_reprobe() for non-operational devices.
- Introduce io_subchannel_create_ccwdev().

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

---
 drivers/s390/cio/css.c        |   13 +++--
 drivers/s390/cio/css.h        |    2 
 drivers/s390/cio/device.c     |  102 +++++++++++++++++++++++++-----------------
 drivers/s390/cio/device_fsm.c |    3 -
 4 files changed, 75 insertions(+), 45 deletions(-)

--- linux-2.6-CH.orig/drivers/s390/cio/css.c
+++ linux-2.6-CH/drivers/s390/cio/css.c
@@ -135,14 +135,19 @@ css_register_subchannel(struct subchanne
 	sch->dev.parent = &css[0]->device;
 	sch->dev.bus = &css_bus_type;
 	sch->dev.release = &css_subchannel_release;
-	
+
 	/* make it known to the system */
 	ret = css_sch_device_register(sch);
-	if (ret)
+	if (ret) {
 		printk (KERN_WARNING "%s: could not register %s\n",
 			__func__, sch->dev.bus_id);
-	else
-		css_get_ssd_info(sch);
+		return ret;
+	}
+	css_get_ssd_info(sch);
+	ret = subchannel_add_files(&sch->dev);
+	if (ret)
+		printk(KERN_WARNING "%s: could not add attributes to %s\n",
+		       __func__, sch->dev.bus_id);
 	return ret;
 }
 
--- linux-2.6-CH.orig/drivers/s390/cio/css.h
+++ linux-2.6-CH/drivers/s390/cio/css.h
@@ -184,4 +184,6 @@ extern int need_rescan;
 
 extern struct workqueue_struct *slow_path_wq;
 extern struct work_struct slow_path_work;
+
+int subchannel_add_files (struct device *);
 #endif
--- linux-2.6-CH.orig/drivers/s390/cio/device.c
+++ linux-2.6-CH/drivers/s390/cio/device.c
@@ -294,6 +294,16 @@ online_show (struct device *dev, struct 
 	return sprintf(buf, cdev->online ? "1\n" : "0\n");
 }
 
+static void ccw_device_unregister(void *data)
+{
+	struct ccw_device *cdev;
+
+	cdev = (struct ccw_device *)data;
+	if (test_and_clear_bit(1, &cdev->private->registered))
+		device_unregister(&cdev->dev);
+	put_device(&cdev->dev);
+}
+
 static void
 ccw_device_remove_disconnected(struct ccw_device *cdev)
 {
@@ -498,8 +508,7 @@ static struct attribute_group subch_attr
 	.attrs = subch_attrs,
 };
 
-static inline int
-subchannel_add_files (struct device *dev)
+int subchannel_add_files (struct device *dev)
 {
 	return sysfs_create_group(&dev->kobj, &subch_attr_group);
 }
@@ -673,6 +682,54 @@ ccw_device_release(struct device *dev)
 	kfree(cdev);
 }
 
+static struct ccw_device * io_subchannel_allocate_dev(struct subchannel *sch)
+{
+	struct ccw_device *cdev;
+
+	cdev  = kzalloc(sizeof(*cdev), GFP_KERNEL);
+	if (cdev) {
+		cdev->private = kzalloc(sizeof(struct ccw_device_private),
+					GFP_KERNEL | GFP_DMA);
+		if (cdev->private)
+			return cdev;
+	}
+	kfree(cdev);
+	return ERR_PTR(-ENOMEM);
+}
+
+static int io_subchannel_initialize_dev(struct subchannel *sch,
+					struct ccw_device *cdev)
+{
+	atomic_set(&cdev->private->onoff, 0);
+	cdev->dev.parent = &sch->dev;
+	cdev->dev.release = ccw_device_release;
+	INIT_LIST_HEAD(&cdev->private->kick_work.entry);
+	/* Do first half of device_register. */
+	device_initialize(&cdev->dev);
+	if (!get_device(&sch->dev)) {
+		if (cdev->dev.release)
+			cdev->dev.release(&cdev->dev);
+		return -ENODEV;
+	}
+	return 0;
+}
+
+static struct ccw_device * io_subchannel_create_ccwdev(struct subchannel *sch)
+{
+	struct ccw_device *cdev;
+	int ret;
+
+	cdev = io_subchannel_allocate_dev(sch);
+	if (!IS_ERR(cdev)) {
+		ret = io_subchannel_initialize_dev(sch, cdev);
+		if (ret) {
+			kfree(cdev);
+			cdev = ERR_PTR(ret);
+		}
+	}
+	return cdev;
+}
+
 /*
  * Register recognized device.
  */
@@ -707,11 +764,6 @@ io_subchannel_register(void *data)
 			wake_up(&ccw_device_init_wq);
 		return;
 	}
-
-	ret = subchannel_add_files(cdev->dev.parent);
-	if (ret)
-		printk(KERN_WARNING "%s: could not add attributes to %s\n",
-		       __func__, sch->dev.bus_id);
 	put_device(&cdev->dev);
 out:
 	cdev->private->flags.recog_done = 1;
@@ -831,7 +883,6 @@ io_subchannel_probe (struct subchannel *
 		cdev = sch->dev.driver_data;
 		device_initialize(&cdev->dev);
 		ccw_device_register(cdev);
-		subchannel_add_files(&sch->dev);
 		/*
 		 * Check if the device is already online. If it is
 		 * the reference count needs to be corrected
@@ -844,27 +895,9 @@ io_subchannel_probe (struct subchannel *
 			get_device(&cdev->dev);
 		return 0;
 	}
-	cdev = kzalloc (sizeof(*cdev), GFP_KERNEL);
-	if (!cdev)
-		return -ENOMEM;
-	cdev->private = kzalloc(sizeof(struct ccw_device_private),
-				GFP_KERNEL | GFP_DMA);
-	if (!cdev->private) {
-		kfree(cdev);
-		return -ENOMEM;
-	}
-	atomic_set(&cdev->private->onoff, 0);
-	cdev->dev.parent = &sch->dev;
-	cdev->dev.release = ccw_device_release;
-	INIT_LIST_HEAD(&cdev->private->kick_work.entry);
-	/* Do first half of device_register. */
-	device_initialize(&cdev->dev);
-
-	if (!get_device(&sch->dev)) {
-		if (cdev->dev.release)
-			cdev->dev.release(&cdev->dev);
-		return -ENODEV;
-	}
+	cdev = io_subchannel_create_ccwdev(sch);
+	if (IS_ERR(cdev))
+		return PTR_ERR(cdev);
 
 	rc = io_subchannel_recog(cdev, sch);
 	if (rc) {
@@ -878,17 +911,6 @@ io_subchannel_probe (struct subchannel *
 	return rc;
 }
 
-static void
-ccw_device_unregister(void *data)
-{
-	struct ccw_device *cdev;
-
-	cdev = (struct ccw_device *)data;
-	if (test_and_clear_bit(1, &cdev->private->registered))
-		device_unregister(&cdev->dev);
-	put_device(&cdev->dev);
-}
-
 static int
 io_subchannel_remove (struct subchannel *sch)
 {
--- linux-2.6-CH.orig/drivers/s390/cio/device_fsm.c
+++ linux-2.6-CH/drivers/s390/cio/device_fsm.c
@@ -1077,7 +1077,8 @@ device_trigger_reprobe(struct subchannel
 	/* Update some values. */
 	if (stsch(sch->schid, &sch->schib))
 		return;
-
+	if (!sch->schib.pmcw.dnv)
+		return;
 	/*
 	 * The pim, pam, pom values may not be accurate, but they are the best
 	 * we have before performing device selection :/

[RFC/Patch 4/5] s390: Make the per-subchannel lock dynamic.

[Cornelia Huck]

From: Cornelia Huck <cornelia.huck@de.ibm.com>

Convert the subchannel lock to a pointer to a lock. Needed for the dynamic
subchannel mapping patch.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

---
 drivers/s390/cio/chsc.c       |   28 ++++++++++----------
 drivers/s390/cio/cio.c        |   58 +++++++++++++++++++++++++++++-------------
 drivers/s390/cio/cio.h        |    4 ++
 drivers/s390/cio/css.c        |   22 ++++++++-------
 drivers/s390/cio/device.c     |   21 ++++++++++-----
 drivers/s390/cio/device_ops.c |   28 ++++++++++----------
 6 files changed, 98 insertions(+), 63 deletions(-)

--- linux-2.6-CH.orig/drivers/s390/cio/chsc.c
+++ linux-2.6-CH/drivers/s390/cio/chsc.c
@@ -183,7 +183,7 @@ css_get_ssd_info(struct subchannel *sch)
 	page = (void *)get_zeroed_page(GFP_KERNEL | GFP_DMA);
 	if (!page)
 		return -ENOMEM;
-	spin_lock_irq(&sch->lock);
+	spin_lock_irq(sch->lock);
 	ret = chsc_get_sch_desc_irq(sch, page);
 	if (ret) {
 		static int cio_chsc_err_msg;
@@ -197,7 +197,7 @@ css_get_ssd_info(struct subchannel *sch)
 			cio_chsc_err_msg = 1;
 		}
 	}
-	spin_unlock_irq(&sch->lock);
+	spin_unlock_irq(sch->lock);
 	free_page((unsigned long)page);
 	if (!ret) {
 		int j, chpid, mask;
@@ -233,7 +233,7 @@ s390_subchannel_remove_chpid(struct devi
 	if (j >= 8)
 		return 0;
 
-	spin_lock_irq(&sch->lock);
+	spin_lock_irq(sch->lock);
 
 	stsch(sch->schid, &schib);
 	if (!schib.pmcw.dnv)
@@ -263,10 +263,10 @@ s390_subchannel_remove_chpid(struct devi
 	else if (sch->lpm == mask)
 		goto out_unreg;
 out_unlock:
-	spin_unlock_irq(&sch->lock);
+	spin_unlock_irq(sch->lock);
 	return 0;
 out_unreg:
-	spin_unlock_irq(&sch->lock);
+	spin_unlock_irq(sch->lock);
 	sch->lpm = 0;
 	if (css_enqueue_subchannel_slow(sch->schid)) {
 		css_clear_subchannel_slow_list();
@@ -376,12 +376,12 @@ __s390_process_res_acc(struct subchannel
 		/* Check if a subchannel is newly available. */
 		return s390_process_res_acc_new_sch(schid);
 
-	spin_lock_irq(&sch->lock);
+	spin_lock_irq(sch->lock);
 
 	chp_mask = s390_process_res_acc_sch(res_data, sch);
 
 	if (chp_mask == 0) {
-		spin_unlock_irq(&sch->lock);
+		spin_unlock_irq(sch->lock);
 		put_device(&sch->dev);
 		return 0;
 	}
@@ -395,7 +395,7 @@ __s390_process_res_acc(struct subchannel
 	else if (sch->driver && sch->driver->verify)
 		sch->driver->verify(&sch->dev);
 
-	spin_unlock_irq(&sch->lock);
+	spin_unlock_irq(sch->lock);
 	put_device(&sch->dev);
 	return 0;
 }
@@ -633,21 +633,21 @@ __chp_add(struct subchannel_id schid, vo
 	if (!sch)
 		/* Check if the subchannel is now available. */
 		return __chp_add_new_sch(schid);
-	spin_lock_irq(&sch->lock);
+	spin_lock_irq(sch->lock);
 	for (i=0; i<8; i++) {
 		mask = 0x80 >> i;
 		if ((sch->schib.pmcw.pim & mask) &&
 		    (sch->schib.pmcw.chpid[i] == chp->id)) {
 			if (stsch(sch->schid, &sch->schib) != 0) {
 				/* Endgame. */
-				spin_unlock_irq(&sch->lock);
+				spin_unlock_irq(sch->lock);
 				return -ENXIO;
 			}
 			break;
 		}
 	}
 	if (i==8) {
-		spin_unlock_irq(&sch->lock);
+		spin_unlock_irq(sch->lock);
 		return 0;
 	}
 	sch->lpm = ((sch->schib.pmcw.pim &
@@ -658,7 +658,7 @@ __chp_add(struct subchannel_id schid, vo
 	if (sch->driver && sch->driver->verify)
 		sch->driver->verify(&sch->dev);
 
-	spin_unlock_irq(&sch->lock);
+	spin_unlock_irq(sch->lock);
 	put_device(&sch->dev);
 	return 0;
 }
@@ -731,7 +731,7 @@ __s390_subchannel_vary_chpid(struct subc
 	if (!sch->ssd_info.valid)
 		return;
 	
-	spin_lock_irqsave(&sch->lock, flags);
+	spin_lock_irqsave(sch->lock, flags);
 	old_lpm = sch->lpm;
 	for (chp = 0; chp < 8; chp++) {
 		if (sch->ssd_info.chpid[chp] != chpid)
@@ -760,7 +760,7 @@ __s390_subchannel_vary_chpid(struct subc
 		}
 		break;
 	}
-	spin_unlock_irqrestore(&sch->lock, flags);
+	spin_unlock_irqrestore(sch->lock, flags);
 }
 
 static int
--- linux-2.6-CH.orig/drivers/s390/cio/cio.c
+++ linux-2.6-CH/drivers/s390/cio/cio.c
@@ -141,11 +141,11 @@ cio_tpi(void)
 		return 1;
 	local_bh_disable();
 	irq_enter ();
-	spin_lock(&sch->lock);
+	spin_lock(sch->lock);
 	memcpy (&sch->schib.scsw, &irb->scsw, sizeof (struct scsw));
 	if (sch->driver && sch->driver->irq)
 		sch->driver->irq(&sch->dev);
-	spin_unlock(&sch->lock);
+	spin_unlock(sch->lock);
 	irq_exit ();
 	_local_bh_enable();
 	return 1;
@@ -494,6 +494,15 @@ cio_disable_subchannel (struct subchanne
 	return ret;
 }
 
+static int cio_create_sch_lock(struct subchannel *sch)
+{
+	sch->lock = kmalloc(sizeof(spinlock_t), GFP_KERNEL);
+	if (!sch->lock)
+		return -ENOMEM;
+	spin_lock_init(sch->lock);
+	return 0;
+}
+
 /*
  * cio_validate_subchannel()
  *
@@ -511,6 +520,7 @@ cio_validate_subchannel (struct subchann
 {
 	char dbf_txt[15];
 	int ccode;
+	int err;
 
 	sprintf (dbf_txt, "valsch%x", schid.sch_no);
 	CIO_TRACE_EVENT (4, dbf_txt);
@@ -518,9 +528,15 @@ cio_validate_subchannel (struct subchann
 	/* Nuke all fields. */
 	memset(sch, 0, sizeof(struct subchannel));
 
-	spin_lock_init(&sch->lock);
+	sch->schid = schid;
+	if (cio_is_console(schid)) {
+		sch->lock = cio_get_console_lock();
+	} else {
+		err = cio_create_sch_lock(sch);
+		if (err)
+			goto out;
+	}
 	mutex_init(&sch->reg_mutex);
-
 	/* Set a name for the subchannel */
 	snprintf (sch->dev.bus_id, BUS_ID_SIZE, "0.%x.%04x", schid.ssid,
 		  schid.sch_no);
@@ -532,10 +548,10 @@ cio_validate_subchannel (struct subchann
 	 *  is not valid.
 	 */
 	ccode = stsch_err (schid, &sch->schib);
-	if (ccode)
-		return (ccode == 3) ? -ENXIO : ccode;
-
-	sch->schid = schid;
+	if (ccode) {
+		err = (ccode == 3) ? -ENXIO : ccode;
+		goto out;
+	}
 	/* Copy subchannel type from path management control word. */
 	sch->st = sch->schib.pmcw.st;
 
@@ -548,14 +564,16 @@ cio_validate_subchannel (struct subchann
 			  "non-I/O subchannel type %04X\n",
 			  sch->schid.ssid, sch->schid.sch_no, sch->st);
 		/* We stop here for non-io subchannels. */
-		return sch->st;
+		err = sch->st;
+		goto out;
 	}
 
 	/* Initialization for io subchannels. */
-	if (!sch->schib.pmcw.dnv)
+	if (!sch->schib.pmcw.dnv) {
 		/* io subchannel but device number is invalid. */
-		return -ENODEV;
-
+		err = -ENODEV;
+		goto out;
+	}
 	/* Devno is valid. */
 	if (is_blacklisted (sch->schid.ssid, sch->schib.pmcw.dev)) {
 		/*
@@ -565,7 +583,8 @@ cio_validate_subchannel (struct subchann
 		CIO_MSG_EVENT(0, "Blacklisted device detected "
 			      "at devno %04X, subchannel set %x\n",
 			      sch->schib.pmcw.dev, sch->schid.ssid);
-		return -ENODEV;
+		err = -ENODEV;
+		goto out;
 	}
 	sch->opm = 0xff;
 	if (!cio_is_console(sch->schid))
@@ -593,6 +612,11 @@ cio_validate_subchannel (struct subchann
 	if ((sch->lpm & (sch->lpm - 1)) != 0)
 		sch->schib.pmcw.mp = 1;	/* multipath mode */
 	return 0;
+out:
+	if (!cio_is_console(schid))
+		kfree(sch->lock);
+	sch->lock = NULL;
+	return err;
 }
 
 /*
@@ -635,7 +659,7 @@ do_IRQ (struct pt_regs *regs)
 		}
 		sch = (struct subchannel *)(unsigned long)tpi_info->intparm;
 		if (sch)
-			spin_lock(&sch->lock);
+			spin_lock(sch->lock);
 		/* Store interrupt response block to lowcore. */
 		if (tsch (tpi_info->schid, irb) == 0 && sch) {
 			/* Keep subchannel information word up to date. */
@@ -646,7 +670,7 @@ do_IRQ (struct pt_regs *regs)
 				sch->driver->irq(&sch->dev);
 		}
 		if (sch)
-			spin_unlock(&sch->lock);
+			spin_unlock(sch->lock);
 		/*
 		 * Are more interrupts pending?
 		 * If so, the tpi instruction will update the lowcore
@@ -685,10 +709,10 @@ wait_cons_dev (void)
 	__ctl_load (cr6, 6, 6);
 
 	do {
-		spin_unlock(&console_subchannel.lock);
+		spin_unlock(console_subchannel.lock);
 		if (!cio_tpi())
 			cpu_relax();
-		spin_lock(&console_subchannel.lock);
+		spin_lock(console_subchannel.lock);
 	} while (console_subchannel.schib.scsw.actl != 0);
 	/*
 	 * restore previous isc value
--- linux-2.6-CH.orig/drivers/s390/cio/cio.h
+++ linux-2.6-CH/drivers/s390/cio/cio.h
@@ -87,7 +87,7 @@ struct orb {
 /* subchannel data structure used by I/O subroutines */
 struct subchannel {
 	struct subchannel_id schid;
-	spinlock_t lock;	/* subchannel lock */
+	spinlock_t *lock;	/* subchannel lock */
 	struct mutex reg_mutex;
 	enum {
 		SUBCHANNEL_TYPE_IO = 0,
@@ -137,9 +137,11 @@ extern struct subchannel *cio_probe_cons
 extern void cio_release_console(void);
 extern int cio_is_console(struct subchannel_id);
 extern struct subchannel *cio_get_console_subchannel(void);
+extern spinlock_t * cio_get_console_lock(void);
 #else
 #define cio_is_console(schid) 0
 #define cio_get_console_subchannel() NULL
+#define cio_get_console_lock() NULL;
 #endif
 
 extern int cio_show_msg;
--- linux-2.6-CH.orig/drivers/s390/cio/css.c
+++ linux-2.6-CH/drivers/s390/cio/css.c
@@ -91,9 +91,9 @@ css_free_subchannel(struct subchannel *s
 		/* Reset intparm to zeroes. */
 		sch->schib.pmcw.intparm = 0;
 		cio_modify(sch);
+		kfree(sch->lock);
 		kfree(sch);
 	}
-	
 }
 
 static void
@@ -102,8 +102,10 @@ css_subchannel_release(struct device *de
 	struct subchannel *sch;
 
 	sch = to_subchannel(dev);
-	if (!cio_is_console(sch->schid))
+	if (!cio_is_console(sch->schid)) {
+		kfree(sch->lock);
 		kfree(sch);
+	}
 }
 
 extern int css_get_ssd_info(struct subchannel *sch);
@@ -206,18 +208,18 @@ static int css_evaluate_known_subchannel
 	unsigned long flags;
 	enum { NONE, UNREGISTER, UNREGISTER_PROBE, REPROBE } action;
 
-	spin_lock_irqsave(&sch->lock, flags);
+	spin_lock_irqsave(sch->lock, flags);
 	disc = device_is_disconnected(sch);
 	if (disc && slow) {
 		/* Disconnected devices are evaluated directly only.*/
-		spin_unlock_irqrestore(&sch->lock, flags);
+		spin_unlock_irqrestore(sch->lock, flags);
 		return 0;
 	}
 	/* No interrupt after machine check - kill pending timers. */
 	device_kill_pending_timer(sch);
 	if (!disc && !slow) {
 		/* Non-disconnected devices are evaluated on the slow path. */
-		spin_unlock_irqrestore(&sch->lock, flags);
+		spin_unlock_irqrestore(sch->lock, flags);
 		return -EAGAIN;
 	}
 	event = css_get_subchannel_status(sch);
@@ -242,9 +244,9 @@ static int css_evaluate_known_subchannel
 		/* Ask driver what to do with device. */
 		action = UNREGISTER;
 		if (sch->driver && sch->driver->notify) {
-			spin_unlock_irqrestore(&sch->lock, flags);
+			spin_unlock_irqrestore(sch->lock, flags);
 			ret = sch->driver->notify(&sch->dev, event);
-			spin_lock_irqsave(&sch->lock, flags);
+			spin_lock_irqsave(sch->lock, flags);
 			if (ret)
 				action = NONE;
 		}
@@ -269,9 +271,9 @@ static int css_evaluate_known_subchannel
 	case UNREGISTER:
 	case UNREGISTER_PROBE:
 		/* Unregister device (will use subchannel lock). */
-		spin_unlock_irqrestore(&sch->lock, flags);
+		spin_unlock_irqrestore(sch->lock, flags);
 		css_sch_device_unregister(sch);
-		spin_lock_irqsave(&sch->lock, flags);
+		spin_lock_irqsave(sch->lock, flags);
 
 		/* Reset intparm to zeroes. */
 		sch->schib.pmcw.intparm = 0;
@@ -283,7 +285,7 @@ static int css_evaluate_known_subchannel
 	default:
 		break;
 	}
-	spin_unlock_irqrestore(&sch->lock, flags);
+	spin_unlock_irqrestore(sch->lock, flags);
 	/* Probe if necessary. */
 	if (action == UNREGISTER_PROBE)
 		ret = css_probe_device(sch->schid);
--- linux-2.6-CH.orig/drivers/s390/cio/device.c
+++ linux-2.6-CH/drivers/s390/cio/device.c
@@ -754,9 +754,9 @@ io_subchannel_register(void *data)
 		printk (KERN_WARNING "%s: could not register %s\n",
 			__func__, cdev->dev.bus_id);
 		put_device(&cdev->dev);
-		spin_lock_irqsave(&sch->lock, flags);
+		spin_lock_irqsave(sch->lock, flags);
 		sch->dev.driver_data = NULL;
-		spin_unlock_irqrestore(&sch->lock, flags);
+		spin_unlock_irqrestore(sch->lock, flags);
 		kfree (cdev->private);
 		kfree (cdev);
 		put_device(&sch->dev);
@@ -837,7 +837,7 @@ io_subchannel_recog(struct ccw_device *c
 
 	sch->dev.driver_data = cdev;
 	sch->driver = &io_subchannel_driver;
-	cdev->ccwlock = &sch->lock;
+	cdev->ccwlock = sch->lock;
 
 	/* Init private data. */
 	priv = cdev->private;
@@ -857,9 +857,9 @@ io_subchannel_recog(struct ccw_device *c
 	atomic_inc(&ccw_device_init_count);
 
 	/* Start async. device sensing. */
-	spin_lock_irq(&sch->lock);
+	spin_lock_irq(sch->lock);
 	rc = ccw_device_recognition(cdev);
-	spin_unlock_irq(&sch->lock);
+	spin_unlock_irq(sch->lock);
 	if (rc) {
 		if (atomic_dec_and_test(&ccw_device_init_count))
 			wake_up(&ccw_device_init_wq);
@@ -901,9 +901,9 @@ io_subchannel_probe (struct subchannel *
 
 	rc = io_subchannel_recog(cdev, sch);
 	if (rc) {
-		spin_lock_irqsave(&sch->lock, flags);
+		spin_lock_irqsave(sch->lock, flags);
 		sch->dev.driver_data = NULL;
-		spin_unlock_irqrestore(&sch->lock, flags);
+		spin_unlock_irqrestore(sch->lock, flags);
 		if (cdev->dev.release)
 			cdev->dev.release(&cdev->dev);
 	}
@@ -1010,6 +1010,13 @@ static struct ccw_device console_cdev;
 static struct ccw_device_private console_private;
 static int console_cdev_in_use;
 
+static DEFINE_SPINLOCK(ccw_console_lock);
+
+spinlock_t * cio_get_console_lock(void)
+{
+	return &ccw_console_lock;
+}
+
 static int
 ccw_device_console_enable (struct ccw_device *cdev, struct subchannel *sch)
 {
--- linux-2.6-CH.orig/drivers/s390/cio/device_ops.c
+++ linux-2.6-CH/drivers/s390/cio/device_ops.c
@@ -316,9 +316,9 @@ __ccw_device_retry_loop(struct ccw_devic
 			ccw_device_set_timeout(cdev, 0);
 		if (ret == -EBUSY) {
 			/* Try again later. */
-			spin_unlock_irq(&sch->lock);
+			spin_unlock_irq(sch->lock);
 			msleep(10);
-			spin_lock_irq(&sch->lock);
+			spin_lock_irq(sch->lock);
 			continue;
 		}
 		if (ret != 0)
@@ -326,12 +326,12 @@ __ccw_device_retry_loop(struct ccw_devic
 			break;
 		/* Wait for end of request. */
 		cdev->private->intparm = magic;
-		spin_unlock_irq(&sch->lock);
+		spin_unlock_irq(sch->lock);
 		wait_event(cdev->private->wait_q,
 			   (cdev->private->intparm == -EIO) ||
 			   (cdev->private->intparm == -EAGAIN) ||
 			   (cdev->private->intparm == 0));
-		spin_lock_irq(&sch->lock);
+		spin_lock_irq(sch->lock);
 		/* Check at least for channel end / device end */
 		if (cdev->private->intparm == -EIO) {
 			/* Non-retryable error. */
@@ -342,9 +342,9 @@ __ccw_device_retry_loop(struct ccw_devic
 			/* Success. */
 			break;
 		/* Try again later. */
-		spin_unlock_irq(&sch->lock);
+		spin_unlock_irq(sch->lock);
 		msleep(10);
-		spin_lock_irq(&sch->lock);
+		spin_lock_irq(sch->lock);
 	} while (1);
 
 	return ret;
@@ -389,7 +389,7 @@ read_dev_chars (struct ccw_device *cdev,
 		return ret;
 	}
 
-	spin_lock_irq(&sch->lock);
+	spin_lock_irq(sch->lock);
 	/* Save interrupt handler. */
 	handler = cdev->handler;
 	/* Temporarily install own handler. */
@@ -406,7 +406,7 @@ read_dev_chars (struct ccw_device *cdev,
 
 	/* Restore interrupt handler. */
 	cdev->handler = handler;
-	spin_unlock_irq(&sch->lock);
+	spin_unlock_irq(sch->lock);
 
 	clear_normalized_cda (rdc_ccw);
 	kfree(rdc_ccw);
@@ -463,7 +463,7 @@ read_conf_data_lpm (struct ccw_device *c
 	rcd_ccw->count = ciw->count;
 	rcd_ccw->flags = CCW_FLAG_SLI;
 
-	spin_lock_irq(&sch->lock);
+	spin_lock_irq(sch->lock);
 	/* Save interrupt handler. */
 	handler = cdev->handler;
 	/* Temporarily install own handler. */
@@ -480,7 +480,7 @@ read_conf_data_lpm (struct ccw_device *c
 
 	/* Restore interrupt handler. */
 	cdev->handler = handler;
-	spin_unlock_irq(&sch->lock);
+	spin_unlock_irq(sch->lock);
 
  	/*
  	 * on success we update the user input parms
@@ -537,7 +537,7 @@ ccw_device_stlck(struct ccw_device *cdev
 		kfree(buf);
 		return -ENOMEM;
 	}
-	spin_lock_irqsave(&sch->lock, flags);
+	spin_lock_irqsave(sch->lock, flags);
 	ret = cio_enable_subchannel(sch, 3);
 	if (ret)
 		goto out_unlock;
@@ -559,9 +559,9 @@ ccw_device_stlck(struct ccw_device *cdev
 		goto out_unlock;
 	}
 	cdev->private->irb.scsw.actl |= SCSW_ACTL_START_PEND;
-	spin_unlock_irqrestore(&sch->lock, flags);
+	spin_unlock_irqrestore(sch->lock, flags);
 	wait_event(cdev->private->wait_q, cdev->private->irb.scsw.actl == 0);
-	spin_lock_irqsave(&sch->lock, flags);
+	spin_lock_irqsave(sch->lock, flags);
 	cio_disable_subchannel(sch); //FIXME: return code?
 	if ((cdev->private->irb.scsw.dstat !=
 	     (DEV_STAT_CHN_END|DEV_STAT_DEV_END)) ||
@@ -572,7 +572,7 @@ ccw_device_stlck(struct ccw_device *cdev
 out_unlock:
 	kfree(buf);
 	kfree(buf2);
-	spin_unlock_irqrestore(&sch->lock, flags);
+	spin_unlock_irqrestore(sch->lock, flags);
 	return ret;
 }
 

[RFC/Patch 5/5] s390: Dynamic subchannel mapping of ccw devices.

[Cornelia Huck]

From: Cornelia Huck <cornelia.huck@de.ibm.com>

Support for disconnected devices reappearing on another subchannel:
- create a 'pseudo_subchannel' per channel subsystem (the 'orphanage')
- use the orphanage as a shelter for ccw_devices that can't remain on the same
  subchannel

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

---
 drivers/s390/cio/cio.c        |    6 
 drivers/s390/cio/cio.h        |    2 
 drivers/s390/cio/css.c        |   37 ++++-
 drivers/s390/cio/css.h        |    4 
 drivers/s390/cio/device.c     |  294 +++++++++++++++++++++++++++++++++++-------
 drivers/s390/cio/device.h     |    2 
 drivers/s390/cio/device_fsm.c |   17 +-
 7 files changed, 306 insertions(+), 56 deletions(-)

--- linux-2.6-CH.orig/drivers/s390/cio/cio.c
+++ linux-2.6-CH/drivers/s390/cio/cio.c
@@ -413,6 +413,8 @@ cio_enable_subchannel (struct subchannel
 	CIO_TRACE_EVENT (2, "ensch");
 	CIO_TRACE_EVENT (2, sch->dev.bus_id);
 
+	if (sch_is_pseudo_sch(sch))
+		return -EINVAL;
 	ccode = stsch (sch->schid, &sch->schib);
 	if (ccode)
 		return -ENODEV;
@@ -460,6 +462,8 @@ cio_disable_subchannel (struct subchanne
 	CIO_TRACE_EVENT (2, "dissch");
 	CIO_TRACE_EVENT (2, sch->dev.bus_id);
 
+	if (sch_is_pseudo_sch(sch))
+		return 0;
 	ccode = stsch (sch->schid, &sch->schib);
 	if (ccode == 3)		/* Not operational. */
 		return -ENODEV;
@@ -494,7 +498,7 @@ cio_disable_subchannel (struct subchanne
 	return ret;
 }
 
-static int cio_create_sch_lock(struct subchannel *sch)
+int cio_create_sch_lock(struct subchannel *sch)
 {
 	sch->lock = kmalloc(sizeof(spinlock_t), GFP_KERNEL);
 	if (!sch->lock)
--- linux-2.6-CH.orig/drivers/s390/cio/css.c
+++ linux-2.6-CH/drivers/s390/cio/css.c
@@ -581,12 +581,24 @@ css_cm_enable_store(struct device *dev, 
 
 static DEVICE_ATTR(cm_enable, 0644, css_cm_enable_show, css_cm_enable_store);
 
-static inline void __init
-setup_css(int nr)
+static inline int __init setup_css(int nr)
 {
 	u32 tod_high;
+	int ret;
 
 	memset(css[nr], 0, sizeof(struct channel_subsystem));
+	css[nr]->pseudo_subchannel =
+		kzalloc(sizeof(*css[nr]->pseudo_subchannel), GFP_KERNEL);
+	if (!css[nr]->pseudo_subchannel)
+		return -ENOMEM;
+	css[nr]->pseudo_subchannel->dev.parent = &css[nr]->device;
+	css[nr]->pseudo_subchannel->dev.release = css_subchannel_release;
+	sprintf(css[nr]->pseudo_subchannel->dev.bus_id, "defunct");
+	ret = cio_create_sch_lock(css[nr]->pseudo_subchannel);
+	if (ret) {
+		kfree(css[nr]->pseudo_subchannel);
+		return ret;
+	}
 	mutex_init(&css[nr]->mutex);
 	css[nr]->valid = 1;
 	css[nr]->cssid = nr;
@@ -594,6 +606,7 @@ setup_css(int nr)
 	css[nr]->device.release = channel_subsystem_release;
 	tod_high = (u32) (get_clock() >> 32);
 	css_generate_pgid(css[nr], tod_high);
+	return 0;
 }
 
 /*
@@ -630,10 +643,12 @@ init_channel_subsystem (void)
 			ret = -ENOMEM;
 			goto out_unregister;
 		}
-		setup_css(i);
-		ret = device_register(&css[i]->device);
+		ret = setup_css(i);
 		if (ret)
 			goto out_free;
+		ret = device_register(&css[i]->device);
+		if (ret)
+			goto out_free_all;
 		if (css_characteristics_avail &&
 		    css_chsc_characteristics.secm) {
 			ret = device_create_file(&css[i]->device,
@@ -641,6 +656,9 @@ init_channel_subsystem (void)
 			if (ret)
 				goto out_device;
 		}
+		ret = device_register(&css[i]->pseudo_subchannel->dev);
+		if (ret)
+			goto out_file;
 	}
 	css_init_done = 1;
 
@@ -648,13 +666,19 @@ init_channel_subsystem (void)
 
 	for_each_subchannel(__init_channel_subsystem, NULL);
 	return 0;
+out_file:
+	device_remove_file(&css[i]->device, &dev_attr_cm_enable);
 out_device:
 	device_unregister(&css[i]->device);
+out_free_all:
+	kfree(css[i]->pseudo_subchannel->lock);
+	kfree(css[i]->pseudo_subchannel);
 out_free:
 	kfree(css[i]);
 out_unregister:
 	while (i > 0) {
 		i--;
+		device_unregister(&css[i]->pseudo_subchannel->dev);
 		if (css_characteristics_avail && css_chsc_characteristics.secm)
 			device_remove_file(&css[i]->device,
 					   &dev_attr_cm_enable);
@@ -666,6 +690,11 @@ out:
 	return ret;
 }
 
+int sch_is_pseudo_sch(struct subchannel *sch)
+{
+	return sch == to_css(sch->dev.parent)->pseudo_subchannel;
+}
+
 /*
  * find a driver for a subchannel. They identify by the subchannel
  * type with the exception that the console subchannel driver has its own
--- linux-2.6-CH.orig/drivers/s390/cio/css.h
+++ linux-2.6-CH/drivers/s390/cio/css.h
@@ -157,6 +157,8 @@ struct channel_subsystem {
 	int cm_enabled;
 	void *cub_addr1;
 	void *cub_addr2;
+	/* for orphaned ccw devices */
+	struct subchannel *pseudo_subchannel;
 };
 #define to_css(dev) container_of(dev, struct channel_subsystem, device)
 
@@ -182,6 +184,8 @@ void css_clear_subchannel_slow_list(void
 int css_slow_subchannels_exist(void);
 extern int need_rescan;
 
+int sch_is_pseudo_sch(struct subchannel *);
+
 extern struct workqueue_struct *slow_path_wq;
 extern struct work_struct slow_path_work;
 
--- linux-2.6-CH.orig/drivers/s390/cio/device.c
+++ linux-2.6-CH/drivers/s390/cio/device.c
@@ -23,6 +23,7 @@
 #include <asm/param.h>		/* HZ */
 
 #include "cio.h"
+#include "cio_debug.h"
 #include "css.h"
 #include "device.h"
 #include "ioasm.h"
@@ -294,6 +295,11 @@ online_show (struct device *dev, struct 
 	return sprintf(buf, cdev->online ? "1\n" : "0\n");
 }
 
+int ccw_device_is_orphan(struct ccw_device *cdev)
+{
+	return sch_is_pseudo_sch(to_subchannel(cdev->dev.parent));
+}
+
 static void ccw_device_unregister(void *data)
 {
 	struct ccw_device *cdev;
@@ -308,10 +314,23 @@ static void
 ccw_device_remove_disconnected(struct ccw_device *cdev)
 {
 	struct subchannel *sch;
+	unsigned long flags;
 	/*
 	 * Forced offline in disconnected state means
 	 * 'throw away device'.
 	 */
+	if (ccw_device_is_orphan(cdev)) {
+		/* Deregister ccw device. */
+		spin_lock_irqsave(cdev->ccwlock, flags);
+		cdev->private->state = DEV_STATE_NOT_OPER;
+		spin_unlock_irqrestore(cdev->ccwlock, flags);
+		if (get_device(&cdev->dev)) {
+			PREPARE_WORK(&cdev->private->kick_work,
+				     ccw_device_unregister, cdev);
+			queue_work(ccw_device_work, &cdev->private->kick_work);
+		}
+		return ;
+	}
 	sch = to_subchannel(cdev->dev.parent);
 	css_sch_device_unregister(sch);
 	/* Reset intparm to zeroes. */
@@ -472,6 +491,8 @@ available_show (struct device *dev, stru
 	struct ccw_device *cdev = to_ccwdev(dev);
 	struct subchannel *sch;
 
+	if (ccw_device_is_orphan(cdev))
+		return sprintf(buf, "no device\n");
 	switch (cdev->private->state) {
 	case DEV_STATE_BOXED:
 		return sprintf(buf, "boxed\n");
@@ -572,11 +593,10 @@ match_devno(struct device * dev, void * 
 
 	cdev = to_ccwdev(dev);
 	if ((cdev->private->state == DEV_STATE_DISCONNECTED) &&
+	    !ccw_device_is_orphan(cdev) &&
 	    ccw_dev_id_is_equal(&cdev->private->dev_id, &d->dev_id) &&
-	    (cdev != d->sibling)) {
-		cdev->private->state = DEV_STATE_NOT_OPER;
+	    (cdev != d->sibling))
 		return 1;
-	}
 	return 0;
 }
 
@@ -593,6 +613,28 @@ static struct ccw_device * get_disc_ccwd
 	return dev ? to_ccwdev(dev) : NULL;
 }
 
+static int match_orphan(struct device *dev, void *data)
+{
+	struct ccw_dev_id *dev_id;
+	struct ccw_device *cdev;
+
+	dev_id = data;
+	cdev = to_ccwdev(dev);
+	return ccw_dev_id_is_equal(&cdev->private->dev_id, dev_id);
+}
+
+static struct ccw_device *
+get_orphaned_ccwdev_by_dev_id(struct channel_subsystem *css,
+			      struct ccw_dev_id *dev_id)
+{
+	struct device *dev;
+
+	dev = device_find_child(&css->pseudo_subchannel->dev, dev_id,
+				match_orphan);
+
+	return dev ? to_ccwdev(dev) : NULL;
+}
+
 static void
 ccw_device_add_changed(void *data)
 {
@@ -611,62 +653,18 @@ ccw_device_add_changed(void *data)
 	}
 }
 
-extern int css_get_ssd_info(struct subchannel *sch);
-
 void
 ccw_device_do_unreg_rereg(void *data)
 {
 	struct ccw_device *cdev;
 	struct subchannel *sch;
-	int need_rename;
 
 	cdev = data;
 	sch = to_subchannel(cdev->dev.parent);
-	if (cdev->private->dev_id.devno != sch->schib.pmcw.dev) {
-		/*
-		 * The device number has changed. This is usually only when
-		 * a device has been detached under VM and then re-appeared
-		 * on another subchannel because of a different attachment
-		 * order than before. Ideally, we should should just switch
-		 * subchannels, but unfortunately, this is not possible with
-		 * the current implementation.
-		 * Instead, we search for the old subchannel for this device
-		 * number and deregister so there are no collisions with the
-		 * newly registered ccw_device.
-		 * FIXME: Find another solution so the block layer doesn't
-		 *        get possibly sick...
-		 */
-		struct ccw_device *other_cdev;
-		struct ccw_dev_id dev_id;
 
-		need_rename = 1;
-		dev_id.devno = sch->schib.pmcw.dev;
-		dev_id.ssid = sch->schid.ssid;
-		other_cdev = get_disc_ccwdev_by_dev_id(&dev_id, cdev);
-		if (other_cdev) {
-			struct subchannel *other_sch;
-
-			other_sch = to_subchannel(other_cdev->dev.parent);
-			if (get_device(&other_sch->dev)) {
-				stsch(other_sch->schid, &other_sch->schib);
-				if (other_sch->schib.pmcw.dnv) {
-					other_sch->schib.pmcw.intparm = 0;
-					cio_modify(other_sch);
-				}
-				css_sch_device_unregister(other_sch);
-			}
-		}
-		/* Update ssd info here. */
-		css_get_ssd_info(sch);
-		cdev->private->dev_id.devno = sch->schib.pmcw.dev;
-	} else
-		need_rename = 0;
 	device_remove_files(&cdev->dev);
 	if (test_and_clear_bit(1, &cdev->private->registered))
 		device_del(&cdev->dev);
-	if (need_rename)
-		snprintf (cdev->dev.bus_id, BUS_ID_SIZE, "0.%x.%04x",
-			  sch->schid.ssid, sch->schib.pmcw.dev);
 	PREPARE_WORK(&cdev->private->kick_work,
 		     ccw_device_add_changed, cdev);
 	queue_work(ccw_device_work, &cdev->private->kick_work);
@@ -730,6 +728,129 @@ static struct ccw_device * io_subchannel
 	return cdev;
 }
 
+static int io_subchannel_recog(struct ccw_device *, struct subchannel *);
+
+static void sch_attach_device(struct subchannel *sch,
+			      struct ccw_device *cdev)
+{
+	spin_lock_irq(sch->lock);
+	sch->dev.driver_data = cdev;
+	cdev->private->schid = sch->schid;
+	cdev->ccwlock = sch->lock;
+	device_trigger_reprobe(sch);
+	spin_unlock_irq(sch->lock);
+}
+
+static void sch_attach_disconnected_device(struct subchannel *sch,
+					   struct ccw_device *cdev)
+{
+	struct subchannel *other_sch;
+	int ret;
+
+	other_sch = to_subchannel(get_device(cdev->dev.parent));
+	ret = device_move(&cdev->dev, &sch->dev);
+	if (ret) {
+		CIO_MSG_EVENT(2, "Moving disconnected device 0.%x.%04x failed "
+			      "(ret=%d)!\n", cdev->private->dev_id.ssid,
+			      cdev->private->dev_id.devno, ret);
+		put_device(&other_sch->dev);
+		return;
+	}
+	other_sch->dev.driver_data = NULL;
+	/* No need to keep a subchannel without ccw device around. */
+	css_sch_device_unregister(other_sch);
+	put_device(&other_sch->dev);
+	sch_attach_device(sch, cdev);
+}
+
+static void sch_attach_orphaned_device(struct subchannel *sch,
+				       struct ccw_device *cdev)
+{
+	int ret;
+
+	/* Try to move the ccw device to its new subchannel. */
+	ret = device_move(&cdev->dev, &sch->dev);
+	if (ret) {
+		CIO_MSG_EVENT(0, "Moving device 0.%x.%04x from orphanage "
+			      "failed (ret=%d)!\n",
+			      cdev->private->dev_id.ssid,
+			      cdev->private->dev_id.devno, ret);
+		return;
+	}
+	sch_attach_device(sch, cdev);
+}
+
+static void sch_create_and_recog_new_device(struct subchannel *sch)
+{
+	struct ccw_device *cdev;
+
+	/* Need to allocate a new ccw device. */
+	cdev = io_subchannel_create_ccwdev(sch);
+	if (IS_ERR(cdev)) {
+		/* OK, we did everything we could... */
+		css_sch_device_unregister(sch);
+		return;
+	}
+	spin_lock_irq(sch->lock);
+	sch->dev.driver_data = cdev;
+	spin_unlock_irq(sch->lock);
+	/* Start recognition for the new ccw device. */
+	if (io_subchannel_recog(cdev, sch)) {
+		spin_lock_irq(sch->lock);
+		sch->dev.driver_data = NULL;
+		spin_unlock_irq(sch->lock);
+		if (cdev->dev.release)
+			cdev->dev.release(&cdev->dev);
+		css_sch_device_unregister(sch);
+	}
+}
+
+
+void ccw_device_move_to_orphanage(void *data)
+{
+	struct ccw_device *cdev;
+	struct ccw_device *replacing_cdev;
+	struct subchannel *sch;
+	int ret;
+	struct channel_subsystem *css;
+	struct ccw_dev_id dev_id;
+
+	cdev = (struct ccw_device *) data;
+	sch = to_subchannel(cdev->dev.parent);
+	css = to_css(sch->dev.parent);
+	dev_id.devno = sch->schib.pmcw.dev;
+	dev_id.ssid = sch->schid.ssid;
+
+	/*
+	 * Move the orphaned ccw device to the orphanage so the replacing
+	 * ccw device can take its place on the subchannel.
+	 */
+	ret = device_move(&cdev->dev, &css->pseudo_subchannel->dev);
+	if (ret) {
+		CIO_MSG_EVENT(0, "Moving device 0.%x.%04x to orphanage failed "
+			      "(ret=%d)!\n", cdev->private->dev_id.ssid,
+			      cdev->private->dev_id.devno, ret);
+		return;
+	}
+	cdev->ccwlock = css->pseudo_subchannel->lock;
+	/*
+	 * Search for the replacing ccw device
+	 * - among the disconnected devices
+	 * - in the orphanage
+	 */
+	replacing_cdev = get_disc_ccwdev_by_dev_id(&dev_id, cdev);
+	if (replacing_cdev) {
+		sch_attach_disconnected_device(sch, replacing_cdev);
+		return;
+	}
+	replacing_cdev = get_orphaned_ccwdev_by_dev_id(css, &dev_id);
+	if (replacing_cdev) {
+		sch_attach_orphaned_device(sch, replacing_cdev);
+		return;
+	}
+	sch_create_and_recog_new_device(sch);
+}
+
 /*
  * Register recognized device.
  */
@@ -867,12 +988,61 @@ io_subchannel_recog(struct ccw_device *c
 	return rc;
 }
 
+struct device_pair_struct {
+	struct ccw_device *cdev;
+	struct subchannel *sch;
+};
+
+static void ccw_device_move_to_sch(void *data)
+{
+	struct device_pair_struct *device_pair;
+	int rc;
+	struct subchannel *sch;
+	struct ccw_device *cdev;
+	struct subchannel *former_parent;
+
+	device_pair = data;
+	sch = device_pair->sch;
+	cdev = device_pair->cdev;
+	former_parent = ccw_device_is_orphan(cdev) ?
+		NULL : to_subchannel(get_device(cdev->dev.parent));
+	mutex_lock(&sch->reg_mutex);
+	/* Try to move the ccw device to its new subchannel. */
+	rc = device_move(&cdev->dev, &sch->dev);
+	mutex_unlock(&sch->reg_mutex);
+	if (rc) {
+		CIO_MSG_EVENT(2, "Moving device 0.%x.%04x to subchannel "
+			      "0.%x.%04x failed (ret=%d)!\n",
+			      cdev->private->dev_id.ssid,
+			      cdev->private->dev_id.devno, sch->schid.ssid,
+			      sch->schid.sch_no, rc);
+		css_sch_device_unregister(sch);
+		goto out;
+	}
+	if (former_parent) {
+		spin_lock_irq(former_parent->lock);
+		former_parent->dev.driver_data = NULL;
+		spin_unlock_irq(former_parent->lock);
+		css_sch_device_unregister(former_parent);
+		/* Reset intparm to zeroes. */
+		former_parent->schib.pmcw.intparm = 0;
+		cio_modify(former_parent);
+	}
+	sch_attach_device(sch, cdev);
+out:
+	if (former_parent)
+		put_device(&former_parent->dev);
+	put_device(&cdev->dev);
+	kfree(device_pair);
+}
+
 static int
 io_subchannel_probe (struct subchannel *sch)
 {
 	struct ccw_device *cdev;
 	int rc;
 	unsigned long flags;
+	struct ccw_dev_id dev_id;
 
 	if (sch->dev.driver_data) {
 		/*
@@ -895,6 +1065,36 @@ io_subchannel_probe (struct subchannel *
 			get_device(&cdev->dev);
 		return 0;
 	}
+	/*
+	 * First check if a fitting device may be found amongst the
+	 * disconnected devices or in the orphanage.
+	 */
+	dev_id.devno = sch->schib.pmcw.dev;
+	dev_id.ssid = sch->schid.ssid;
+	cdev = get_disc_ccwdev_by_dev_id(&dev_id, NULL);
+	if (!cdev)
+		cdev = get_orphaned_ccwdev_by_dev_id(to_css(sch->dev.parent),
+						     &dev_id);
+	if (cdev) {
+		/*
+		 * Schedule moving the device until when we have a registered
+		 * subchannel to move to and succeed the probe. We can
+		 * unregister later again, when the probe is through.
+		 */
+		struct device_pair_struct *device_pair;
+
+		device_pair = kmalloc(sizeof(*device_pair), GFP_KERNEL);
+		if (!device_pair) {
+			put_device(&cdev->dev);
+			return -ENOMEM;
+		}
+		device_pair->cdev = cdev;
+		device_pair->sch = sch;
+		PREPARE_WORK(&cdev->private->kick_work,
+			     ccw_device_move_to_sch, device_pair);
+		queue_work(slow_path_wq, &cdev->private->kick_work);
+		return 0;
+	}
 	cdev = io_subchannel_create_ccwdev(sch);
 	if (IS_ERR(cdev))
 		return PTR_ERR(cdev);
--- linux-2.6-CH.orig/drivers/s390/cio/device.h
+++ linux-2.6-CH/drivers/s390/cio/device.h
@@ -80,6 +80,8 @@ int ccw_device_cancel_halt_clear(struct 
 
 void ccw_device_do_unreg_rereg(void *);
 void ccw_device_call_sch_unregister(void *);
+void ccw_device_move_to_orphanage(void *);
+int ccw_device_is_orphan(struct ccw_device *);
 
 int ccw_device_recognition(struct ccw_device *);
 int ccw_device_online(struct ccw_device *);
--- linux-2.6-CH.orig/drivers/s390/cio/device_fsm.c
+++ linux-2.6-CH/drivers/s390/cio/device_fsm.c
@@ -165,13 +165,12 @@ ccw_device_handle_oper(struct ccw_device
 	/*
 	 * Check if cu type and device type still match. If
 	 * not, it is certainly another device and we have to
-	 * de- and re-register. Also check here for non-matching devno.
+	 * de- and re-register.
 	 */
 	if (cdev->id.cu_type != cdev->private->senseid.cu_type ||
 	    cdev->id.cu_model != cdev->private->senseid.cu_model ||
 	    cdev->id.dev_type != cdev->private->senseid.dev_type ||
-	    cdev->id.dev_model != cdev->private->senseid.dev_model ||
-	    cdev->private->dev_id.devno != sch->schib.pmcw.dev) {
+	    cdev->id.dev_model != cdev->private->senseid.dev_model) {
 		PREPARE_WORK(&cdev->private->kick_work,
 			     ccw_device_do_unreg_rereg, cdev);
 		queue_work(ccw_device_work, &cdev->private->kick_work);
@@ -653,6 +652,10 @@ ccw_device_offline(struct ccw_device *cd
 {
 	struct subchannel *sch;
 
+	if (ccw_device_is_orphan(cdev)) {
+		ccw_device_done(cdev, DEV_STATE_OFFLINE);
+		return 0;
+	}
 	sch = to_subchannel(cdev->dev.parent);
 	if (stsch(sch->schid, &sch->schib) || !sch->schib.pmcw.dnv)
 		return -ENODEV;
@@ -1092,7 +1095,13 @@ device_trigger_reprobe(struct subchannel
 		sch->schib.pmcw.mp = 1;
 	sch->schib.pmcw.intparm = (__u32)(unsigned long)sch;
 	/* We should also udate ssd info, but this has to wait. */
-	ccw_device_start_id(cdev, 0);
+	/* Check if this is another device which appeared on the same sch. */
+	if (sch->schib.pmcw.dev != cdev->private->dev_id.devno) {
+		PREPARE_WORK(&cdev->private->kick_work,
+			     ccw_device_move_to_orphanage, cdev);
+		queue_work(ccw_device_work, &cdev->private->kick_work);
+	} else
+		ccw_device_start_id(cdev, 0);
 }
 
 static void
--- linux-2.6-CH.orig/drivers/s390/cio/cio.h
+++ linux-2.6-CH/drivers/s390/cio/cio.h
@@ -131,6 +131,8 @@ extern int cio_set_options (struct subch
 extern int cio_get_options (struct subchannel *);
 extern int cio_modify (struct subchannel *);
 
+int cio_create_sch_lock(struct subchannel *);
+
 /* Use with care. */
 #ifdef CONFIG_CCW_CONSOLE
 extern struct subchannel *cio_probe_console(void);