4 files changed, 284 insertions, 155 deletions

diff --git a/drivers/s390/char/monwriter.c b/drivers/s390/char/monwriter.c
index 268598ef3ef..20442fbf934 100644
--- a/drivers/s390/char/monwriter.c
+++ b/drivers/s390/char/monwriter.c
@@ -17,6 +17,7 @@
 #include <linux/miscdevice.h>
 #include <linux/ctype.h>
 #include <linux/poll.h>
+#include <linux/mutex.h>
 #include <asm/uaccess.h>
 #include <asm/ebcdic.h>
 #include <asm/io.h>
@@ -41,6 +42,7 @@ struct mon_private {
 	size_t hdr_to_read;
 	size_t data_to_read;
 	struct mon_buf *current_buf;
+	struct mutex thread_mutex;
 };
 
 /*
@@ -179,6 +181,7 @@ static int monwrite_open(struct inode *inode, struct file *filp)
 		return -ENOMEM;
 	INIT_LIST_HEAD(&monpriv->list);
 	monpriv->hdr_to_read = sizeof(monpriv->hdr);
+	mutex_init(&monpriv->thread_mutex);
 	filp->private_data = monpriv;
 	return nonseekable_open(inode, filp);
 }
@@ -209,6 +212,7 @@ static ssize_t monwrite_write(struct file *filp, const char __user *data,
 	void *to;
 	int rc;
 
+	mutex_lock(&monpriv->thread_mutex);
 	for (written = 0; written < count; ) {
 		if (monpriv->hdr_to_read) {
 			len = min(count - written, monpriv->hdr_to_read);
@@ -247,11 +251,13 @@ static ssize_t monwrite_write(struct file *filp, const char __user *data,
 		}
 		monpriv->hdr_to_read = sizeof(monpriv->hdr);
 	}
+	mutex_unlock(&monpriv->thread_mutex);
 	return written;
 
 out_error:
 	monpriv->data_to_read = 0;
 	monpriv->hdr_to_read = sizeof(struct monwrite_hdr);
+	mutex_unlock(&monpriv->thread_mutex);
 	return rc;
 }
 
diff --git a/drivers/s390/char/raw3270.c b/drivers/s390/char/raw3270.c
index 4f2f81b16cf..2edd5fb6d3d 100644
--- a/drivers/s390/char/raw3270.c
+++ b/drivers/s390/char/raw3270.c
@@ -21,6 +21,7 @@
 #include <asm/ccwdev.h>
 #include <asm/cio.h>
 #include <asm/ebcdic.h>
+#include <asm/diag.h>
 
 #include "raw3270.h"
 
diff --git a/drivers/s390/char/vmur.c b/drivers/s390/char/vmur.c
index 161867cebd8..d70a6e65bf1 100644
--- a/drivers/s390/char/vmur.c
+++ b/drivers/s390/char/vmur.c
@@ -14,6 +14,7 @@
 #include <asm/cio.h>
 #include <asm/ccwdev.h>
 #include <asm/debug.h>
+#include <asm/diag.h>
 
 #include "vmur.h"
 
@@ -68,8 +69,26 @@ static struct ccw_driver ur_driver = {
 	.set_offline	= ur_set_offline,
 };
 
+static DEFINE_MUTEX(vmur_mutex);
+
 /*
  * Allocation, freeing, getting and putting of urdev structures
+ *
+ * Each ur device (urd) contains a reference to its corresponding ccw device
+ * (cdev) using the urd->cdev pointer. Each ccw device has a reference to the
+ * ur device using the cdev->dev.driver_data pointer.
+ *
+ * urd references:
+ * - ur_probe gets a urd reference, ur_remove drops the reference
+ *   (cdev->dev.driver_data)
+ * - ur_open gets a urd reference, ur_relase drops the reference
+ *   (urf->urd)
+ *
+ * cdev references:
+ * - urdev_alloc get a cdev reference (urd->cdev)
+ * - urdev_free drops the cdev reference (urd->cdev)
+ *
+ * Setting and clearing of cdev->dev.driver_data is protected by the ccwdev lock
  */
 static struct urdev *urdev_alloc(struct ccw_device *cdev)
 {
@@ -78,51 +97,72 @@ static struct urdev *urdev_alloc(struct ccw_device *cdev)
 	urd = kzalloc(sizeof(struct urdev), GFP_KERNEL);
 	if (!urd)
 		return NULL;
-	urd->cdev = cdev;
 	urd->reclen = cdev->id.driver_info;
 	ccw_device_get_id(cdev, &urd->dev_id);
 	mutex_init(&urd->io_mutex);
 	mutex_init(&urd->open_mutex);
+	atomic_set(&urd->ref_count,  1);
+	urd->cdev = cdev;
+	get_device(&cdev->dev);
 	return urd;
 }
 
 static void urdev_free(struct urdev *urd)
 {
+	TRACE("urdev_free: %p\n", urd);
+	if (urd->cdev)
+		put_device(&urd->cdev->dev);
 	kfree(urd);
 }
 
-/*
- * This is how the character device driver gets a reference to a
- * ur device. When this call returns successfully, a reference has
- * been taken (by get_device) on the underlying kobject. The recipient
- * of this urdev pointer must eventually drop it with urdev_put(urd)
- * which does the corresponding put_device().
- */
+static void urdev_get(struct urdev *urd)
+{
+	atomic_inc(&urd->ref_count);
+}
+
+static struct urdev *urdev_get_from_cdev(struct ccw_device *cdev)
+{
+	struct urdev *urd;
+	unsigned long flags;
+
+	spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
+	urd = cdev->dev.driver_data;
+	if (urd)
+		urdev_get(urd);
+	spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
+	return urd;
+}
+
 static struct urdev *urdev_get_from_devno(u16 devno)
 {
 	char bus_id[16];
 	struct ccw_device *cdev;
+	struct urdev *urd;
 
 	sprintf(bus_id, "0.0.%04x", devno);
 	cdev = get_ccwdev_by_busid(&ur_driver, bus_id);
 	if (!cdev)
 		return NULL;
-
-	return cdev->dev.driver_data;
+	urd = urdev_get_from_cdev(cdev);
+	put_device(&cdev->dev);
+	return urd;
 }
 
 static void urdev_put(struct urdev *urd)
 {
-	put_device(&urd->cdev->dev);
+	if (atomic_dec_and_test(&urd->ref_count))
+		urdev_free(urd);
 }
 
 /*
  * Low-level functions to do I/O to a ur device.
  *     alloc_chan_prog
+ *     free_chan_prog
  *     do_ur_io
  *     ur_int_handler
  *
  * alloc_chan_prog allocates and builds the channel program
+ * free_chan_prog frees memory of the channel program
  *
  * do_ur_io issues the channel program to the device and blocks waiting
  * on a completion event it publishes at urd->io_done. The function
@@ -137,6 +177,16 @@ static void urdev_put(struct urdev *urd)
  * address pointer that alloc_chan_prog returned.
  */
 
+static void free_chan_prog(struct ccw1 *cpa)
+{
+	struct ccw1 *ptr = cpa;
+
+	while (ptr->cda) {
+		kfree((void *)(addr_t) ptr->cda);
+		ptr++;
+	}
+	kfree(cpa);
+}
 
 /*
  * alloc_chan_prog
@@ -144,44 +194,45 @@ static void urdev_put(struct urdev *urd)
  * with a final NOP CCW command-chained on (which ensures that CE and DE
  * are presented together in a single interrupt instead of as separate
  * interrupts unless an incorrect length indication kicks in first). The
- * data length in each CCW is reclen. The caller must ensure that count
- * is an integral multiple of reclen.
- * The channel program pointer returned by this function must be freed
- * with kfree. The caller is responsible for checking that
- * count/reclen is not ridiculously large.
+ * data length in each CCW is reclen.
  */
-static struct ccw1 *alloc_chan_prog(char *buf, size_t count, size_t reclen)
+static struct ccw1 *alloc_chan_prog(const char __user *ubuf, int rec_count,
+				    int reclen)
 {
-	size_t num_ccws;
 	struct ccw1 *cpa;
+	void *kbuf;
 	int i;
 
-	TRACE("alloc_chan_prog(%p, %zu, %zu)\n", buf, count, reclen);
+	TRACE("alloc_chan_prog(%p, %i, %i)\n", ubuf, rec_count, reclen);
 
 	/*
 	 * We chain a NOP onto the writes to force CE+DE together.
 	 * That means we allocate room for CCWs to cover count/reclen
 	 * records plus a NOP.
 	 */
-	num_ccws = count / reclen + 1;
-	cpa = kmalloc(num_ccws * sizeof(struct ccw1), GFP_KERNEL | GFP_DMA);
+	cpa = kzalloc((rec_count + 1) * sizeof(struct ccw1),
+		      GFP_KERNEL | GFP_DMA);
 	if (!cpa)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
-	for (i = 0; count; i++) {
+	for (i = 0; i < rec_count; i++) {
 		cpa[i].cmd_code = WRITE_CCW_CMD;
 		cpa[i].flags = CCW_FLAG_CC | CCW_FLAG_SLI;
 		cpa[i].count = reclen;
-		cpa[i].cda = __pa(buf);
-		buf += reclen;
-		count -= reclen;
+		kbuf = kmalloc(reclen, GFP_KERNEL | GFP_DMA);
+		if (!kbuf) {
+			free_chan_prog(cpa);
+			return ERR_PTR(-ENOMEM);
+		}
+		cpa[i].cda = (u32)(addr_t) kbuf;
+		if (copy_from_user(kbuf, ubuf, reclen)) {
+			free_chan_prog(cpa);
+			return ERR_PTR(-EFAULT);
+		}
+		ubuf += reclen;
 	}
 	/* The following NOP CCW forces CE+DE to be presented together */
 	cpa[i].cmd_code = CCW_CMD_NOOP;
-	cpa[i].flags = 0;
-	cpa[i].count = 0;
-	cpa[i].cda = 0;
-
 	return cpa;
 }
 
@@ -189,7 +240,7 @@ static int do_ur_io(struct urdev *urd, struct ccw1 *cpa)
 {
 	int rc;
 	struct ccw_device *cdev = urd->cdev;
-	DECLARE_COMPLETION(event);
+	DECLARE_COMPLETION_ONSTACK(event);
 
 	TRACE("do_ur_io: cpa=%p\n", cpa);
 
@@ -232,6 +283,7 @@ static void ur_int_handler(struct ccw_device *cdev, unsigned long intparm,
 		return;
 	}
 	urd = cdev->dev.driver_data;
+	BUG_ON(!urd);
 	/* On special conditions irb is an error pointer */
 	if (IS_ERR(irb))
 		urd->io_request_rc = PTR_ERR(irb);
@@ -249,9 +301,15 @@ static void ur_int_handler(struct ccw_device *cdev, unsigned long intparm,
 static ssize_t ur_attr_reclen_show(struct device *dev,
 				   struct device_attribute *attr, char *buf)
 {
-	struct urdev *urd = dev->driver_data;
+	struct urdev *urd;
+	int rc;
 
-	return sprintf(buf, "%zu\n", urd->reclen);
+	urd = urdev_get_from_cdev(to_ccwdev(dev));
+	if (!urd)
+		return -ENODEV;
+	rc = sprintf(buf, "%zu\n", urd->reclen);
+	urdev_put(urd);
+	return rc;
 }
 
 static DEVICE_ATTR(reclen, 0444, ur_attr_reclen_show, NULL);
@@ -325,24 +383,11 @@ static ssize_t do_write(struct urdev *urd, const char __user *udata,
 			size_t count, size_t reclen, loff_t *ppos)
 {
 	struct ccw1 *cpa;
-	char *buf;
 	int rc;
 
-	/* Data buffer must be under 2GB line for fmt1 CCWs: hence GFP_DMA */
-	buf = kmalloc(count, GFP_KERNEL | GFP_DMA);
-	if (!buf)
-		return -ENOMEM;
-
-	if (copy_from_user(buf, udata, count)) {
-		rc = -EFAULT;
-		goto fail_kfree_buf;
-	}
-
-	cpa = alloc_chan_prog(buf, count, reclen);
-	if (!cpa) {
-		rc = -ENOMEM;
-		goto fail_kfree_buf;
-	}
+	cpa = alloc_chan_prog(udata, count / reclen, reclen);
+	if (IS_ERR(cpa))
+		return PTR_ERR(cpa);
 
 	rc = do_ur_io(urd, cpa);
 	if (rc)
@@ -354,10 +399,9 @@ static ssize_t do_write(struct urdev *urd, const char __user *udata,
 	}
 	*ppos += count;
 	rc = count;
+
 fail_kfree_cpa:
-	kfree(cpa);
-fail_kfree_buf:
-	kfree(buf);
+	free_chan_prog(cpa);
 	return rc;
 }
 
@@ -380,31 +424,6 @@ static ssize_t ur_write(struct file *file, const char __user *udata,
 	return do_write(urf->urd, udata, count, urf->dev_reclen, ppos);
 }
 
-static int do_diag_14(unsigned long rx, unsigned long ry1,
-		      unsigned long subcode)
-{
-	register unsigned long _ry1 asm("2") = ry1;
-	register unsigned long _ry2 asm("3") = subcode;
-	int rc = 0;
-
-	asm volatile(
-#ifdef CONFIG_64BIT
-		"   sam31\n"
-		"   diag    %2,2,0x14\n"
-		"   sam64\n"
-#else
-		"   diag    %2,2,0x14\n"
-#endif
-		"   ipm     %0\n"
-		"   srl     %0,28\n"
-		: "=d" (rc), "+d" (_ry2)
-		: "d" (rx), "d" (_ry1)
-		: "cc");
-
-	TRACE("diag 14: subcode=0x%lx, cc=%i\n", subcode, rc);
-	return rc;
-}
-
 /*
  * diagnose code 0x14 subcode 0x0028 - position spool file to designated
  *				       record
@@ -416,7 +435,7 @@ static int diag_position_to_record(int devno, int record)
 {
 	int cc;
 
-	cc = do_diag_14(record, devno, 0x28);
+	cc = diag14(record, devno, 0x28);
 	switch (cc) {
 	case 0:
 		return 0;
@@ -441,7 +460,7 @@ static int diag_read_file(int devno, char *buf)
 {
 	int cc;
 
-	cc = do_diag_14((unsigned long) buf, devno, 0x00);
+	cc = diag14((unsigned long) buf, devno, 0x00);
 	switch (cc) {
 	case 0:
 		return 0;
@@ -473,7 +492,7 @@ static ssize_t diag14_read(struct file *file, char __user *ubuf, size_t count,
 		return rc;
 
 	len = min((size_t) PAGE_SIZE, count);
-	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	buf = (char *) __get_free_page(GFP_KERNEL | GFP_DMA);
 	if (!buf)
 		return -ENOMEM;
 
@@ -500,7 +519,7 @@ static ssize_t diag14_read(struct file *file, char __user *ubuf, size_t count,
 	*offs += copied;
 	rc = copied;
 fail:
-	kfree(buf);
+	free_page((unsigned long) buf);
 	return rc;
 }
 
@@ -534,7 +553,7 @@ static int diag_read_next_file_info(struct file_control_block *buf, int spid)
 {
 	int cc;
 
-	cc = do_diag_14((unsigned long) buf, spid, 0xfff);
+	cc = diag14((unsigned long) buf, spid, 0xfff);
 	switch (cc) {
 	case 0:
 		return 0;
@@ -543,56 +562,97 @@ static int diag_read_next_file_info(struct file_control_block *buf, int spid)
 	}
 }
 
-static int verify_device(struct urdev *urd)
+static int verify_uri_device(struct urdev *urd)
 {
-	struct file_control_block fcb;
+	struct file_control_block *fcb;
 	char *buf;
 	int rc;
 
+	fcb = kmalloc(sizeof(*fcb), GFP_KERNEL | GFP_DMA);
+	if (!fcb)
+		return -ENOMEM;
+
+	/* check for empty reader device (beginning of chain) */
+	rc = diag_read_next_file_info(fcb, 0);
+	if (rc)
+		goto fail_free_fcb;
+
+	/* if file is in hold status, we do not read it */
+	if (fcb->file_stat & (FLG_SYSTEM_HOLD | FLG_USER_HOLD)) {
+		rc = -EPERM;
+		goto fail_free_fcb;
+	}
+
+	/* open file on virtual reader	*/
+	buf = (char *) __get_free_page(GFP_KERNEL | GFP_DMA);
+	if (!buf) {
+		rc = -ENOMEM;
+		goto fail_free_fcb;
+	}
+	rc = diag_read_file(urd->dev_id.devno, buf);
+	if ((rc != 0) && (rc != -ENODATA)) /* EOF does not hurt */
+		goto fail_free_buf;
+
+	/* check if the file on top of the queue is open now */
+	rc = diag_read_next_file_info(fcb, 0);
+	if (rc)
+		goto fail_free_buf;
+	if (!(fcb->file_stat & FLG_IN_USE)) {
+		rc = -EMFILE;
+		goto fail_free_buf;
+	}
+	rc = 0;
+
+fail_free_buf:
+	free_page((unsigned long) buf);
+fail_free_fcb:
+	kfree(fcb);
+	return rc;
+}
+
+static int verify_device(struct urdev *urd)
+{
 	switch (urd->class) {
 	case DEV_CLASS_UR_O:
 		return 0; /* no check needed here */
 	case DEV_CLASS_UR_I:
-		/* check for empty reader device (beginning of chain) */
-		rc = diag_read_next_file_info(&fcb, 0);
-		if (rc)
-			return rc;
-
-		/* open file on virtual reader	*/
-		buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
-		if (!buf)
-			return -ENOMEM;
-		rc = diag_read_file(urd->dev_id.devno, buf);
-		kfree(buf);
-
-		if ((rc != 0) && (rc != -ENODATA)) /* EOF does not hurt */
-			return rc;
-		return 0;
+		return verify_uri_device(urd);
 	default:
 		return -ENOTSUPP;
 	}
 }
 
-static int get_file_reclen(struct urdev *urd)
+static int get_uri_file_reclen(struct urdev *urd)
 {
-	struct file_control_block fcb;
+	struct file_control_block *fcb;
 	int rc;
 
+	fcb = kmalloc(sizeof(*fcb), GFP_KERNEL | GFP_DMA);
+	if (!fcb)
+		return -ENOMEM;
+	rc = diag_read_next_file_info(fcb, 0);
+	if (rc)
+		goto fail_free;
+	if (fcb->file_stat & FLG_CP_DUMP)
+		rc = 0;
+	else
+		rc = fcb->rec_len;
+
+fail_free:
+	kfree(fcb);
+	return rc;
+}
+
+static int get_file_reclen(struct urdev *urd)
+{
 	switch (urd->class) {
 	case DEV_CLASS_UR_O:
 		return 0;
 	case DEV_CLASS_UR_I:
-		rc = diag_read_next_file_info(&fcb, 0);
-		if (rc)
-			return rc;
-		break;
+		return get_uri_file_reclen(urd);
 	default:
 		return -ENOTSUPP;
 	}
-	if (fcb.file_stat & FLG_CP_DUMP)
-		return 0;
-
-	return fcb.rec_len;
 }
 
 static int ur_open(struct inode *inode, struct file *file)
@@ -710,64 +770,63 @@ static struct file_operations ur_fops = {
 
 /*
  * ccw_device infrastructure:
- *     ur_probe gets its own ref to the device (i.e. get_device),
- *     creates the struct urdev, the device attributes, sets up
- *     the interrupt handler and validates the virtual unit record device.
- *     ur_remove removes the device attributes, frees the struct urdev
- *     and drops (put_device) the ref to the device we got in ur_probe.
+ *     ur_probe creates the struct urdev (with refcount = 1), the device
+ *     attributes, sets up the interrupt handler and validates the virtual
+ *     unit record device.
+ *     ur_remove removes the device attributes and drops the reference to
+ *     struct urdev.
+ *
+ *     ur_probe, ur_remove, ur_set_online and ur_set_offline are serialized
+ *     by the vmur_mutex lock.
+ *
+ *     urd->char_device is used as indication that the online function has
+ *     been completed successfully.
  */
 static int ur_probe(struct ccw_device *cdev)
 {
 	struct urdev *urd;
 	int rc;
 
-	TRACE("ur_probe: cdev=%p state=%d\n", cdev, *(int *) cdev->private);
-
-	if (!get_device(&cdev->dev))
-		return -ENODEV;
+	TRACE("ur_probe: cdev=%p\n", cdev);
 
+	mutex_lock(&vmur_mutex);
 	urd = urdev_alloc(cdev);
 	if (!urd) {
 		rc = -ENOMEM;
-		goto fail;
+		goto fail_unlock;
 	}
+
 	rc = ur_create_attributes(&cdev->dev);
 	if (rc) {
 		rc = -ENOMEM;
-		goto fail;
+		goto fail_urdev_put;
 	}
-	cdev->dev.driver_data = urd;
 	cdev->handler = ur_int_handler;
 
 	/* validate virtual unit record device */
 	urd->class = get_urd_class(urd);
 	if (urd->class < 0) {
 		rc = urd->class;
-		goto fail;
+		goto fail_remove_attr;
 	}
 	if ((urd->class != DEV_CLASS_UR_I) && (urd->class != DEV_CLASS_UR_O)) {
 		rc = -ENOTSUPP;
-		goto fail;
+		goto fail_remove_attr;
 	}
+	spin_lock_irq(get_ccwdev_lock(cdev));
+	cdev->dev.driver_data = urd;
+	spin_unlock_irq(get_ccwdev_lock(cdev));
 
+	mutex_unlock(&vmur_mutex);
 	return 0;
 
-fail:
-	urdev_free(urd);
-	put_device(&cdev->dev);
-	return rc;
-}
-
-static void ur_remove(struct ccw_device *cdev)
-{
-	struct urdev *urd = cdev->dev.driver_data;
-
-	TRACE("ur_remove\n");
-	if (cdev->online)
-		ur_set_offline(cdev);
+fail_remove_attr:
 	ur_remove_attributes(&cdev->dev);
-	urdev_free(urd);
-	put_device(&cdev->dev);
+fail_urdev_put:
+	urdev_put(urd);
+fail_unlock:
+	mutex_unlock(&vmur_mutex);
+	return rc;
 }
 
 static int ur_set_online(struct ccw_device *cdev)
@@ -776,20 +835,29 @@ static int ur_set_online(struct ccw_device *cdev)
 	int minor, major, rc;
 	char node_id[16];
 
-	TRACE("ur_set_online: cdev=%p state=%d\n", cdev,
-	      *(int *) cdev->private);
+	TRACE("ur_set_online: cdev=%p\n", cdev);
 
-	if (!try_module_get(ur_driver.owner))
-		return -EINVAL;
+	mutex_lock(&vmur_mutex);
+	urd = urdev_get_from_cdev(cdev);
+	if (!urd) {
+		/* ur_remove already deleted our urd */
+		rc = -ENODEV;
+		goto fail_unlock;
+	}
+
+	if (urd->char_device) {
+		/* Another ur_set_online was faster */
+		rc = -EBUSY;
+		goto fail_urdev_put;
+	}
 
-	urd = (struct urdev *) cdev->dev.driver_data;
 	minor = urd->dev_id.devno;
 	major = MAJOR(ur_first_dev_maj_min);
 
 	urd->char_device = cdev_alloc();
 	if (!urd->char_device) {
 		rc = -ENOMEM;
-		goto fail_module_put;
+		goto fail_urdev_put;
 	}
 
 	cdev_init(urd->char_device, &ur_fops);
@@ -818,29 +886,79 @@ static int ur_set_online(struct ccw_device *cdev)
 		TRACE("ur_set_online: device_create rc=%d\n", rc);
 		goto fail_free_cdev;
 	}
-
+	urdev_put(urd);
+	mutex_unlock(&vmur_mutex);
 	return 0;
 
 fail_free_cdev:
 	cdev_del(urd->char_device);
-fail_module_put:
-	module_put(ur_driver.owner);
-
+	urd->char_device = NULL;
+fail_urdev_put:
+	urdev_put(urd);
+fail_unlock:
+	mutex_unlock(&vmur_mutex);
 	return rc;
 }
 
-static int ur_set_offline(struct ccw_device *cdev)
+static int ur_set_offline_force(struct ccw_device *cdev, int force)
 {
 	struct urdev *urd;
+	int rc;
 
-	TRACE("ur_set_offline: cdev=%p cdev->private=%p state=%d\n",
-		cdev, cdev->private, *(int *) cdev->private);
-	urd = (struct urdev *) cdev->dev.driver_data;
+	TRACE("ur_set_offline: cdev=%p\n", cdev);
+	urd = urdev_get_from_cdev(cdev);
+	if (!urd)
+		/* ur_remove already deleted our urd */
+		return -ENODEV;
+	if (!urd->char_device) {
+		/* Another ur_set_offline was faster */
+		rc = -EBUSY;
+		goto fail_urdev_put;
+	}
+	if (!force && (atomic_read(&urd->ref_count) > 2)) {
+		/* There is still a user of urd (e.g. ur_open) */
+		TRACE("ur_set_offline: BUSY\n");
+		rc = -EBUSY;
+		goto fail_urdev_put;
+	}
 	device_destroy(vmur_class, urd->char_device->dev);
 	cdev_del(urd->char_device);
-	module_put(ur_driver.owner);
+	urd->char_device = NULL;
+	rc = 0;
 
-	return 0;
+fail_urdev_put:
+	urdev_put(urd);
+	return rc;
+}
+
+static int ur_set_offline(struct ccw_device *cdev)
+{
+	int rc;
+
+	mutex_lock(&vmur_mutex);
+	rc = ur_set_offline_force(cdev, 0);
+	mutex_unlock(&vmur_mutex);
+	return rc;
+}
+
+static void ur_remove(struct ccw_device *cdev)
+{
+	unsigned long flags;
+
+	TRACE("ur_remove\n");
+
+	mutex_lock(&vmur_mutex);
+
+	if (cdev->online)
+		ur_set_offline_force(cdev, 1);
+	ur_remove_attributes(&cdev->dev);
+
+	spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
+	urdev_put(cdev->dev.driver_data);
+	cdev->dev.driver_data = NULL;
+	spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
+
+	mutex_unlock(&vmur_mutex);
 }
 
 /*
diff --git a/drivers/s390/char/vmur.h b/drivers/s390/char/vmur.h
index 16d0a4e38e4..fa959644735 100644
--- a/drivers/s390/char/vmur.h
+++ b/drivers/s390/char/vmur.h
@@ -50,7 +50,10 @@ struct file_control_block {
 	char  rest[200];
 } __attribute__ ((packed));
 
-#define FLG_CP_DUMP 0x10
+#define FLG_SYSTEM_HOLD	0x04
+#define FLG_CP_DUMP	0x10
+#define FLG_USER_HOLD	0x20
+#define FLG_IN_USE	0x80
 
 /*
  * A struct urdev is created for each ur device that is made available
@@ -67,6 +70,7 @@ struct urdev {
 	size_t reclen;			/* Record length for *write* CCWs */
 	int class;			/* VM device class */
 	int io_request_rc;		/* return code from I/O request */
+	atomic_t ref_count;		/* reference counter */
 };
 
 /*