1 files changed, 54 insertions, 28 deletions

diff --git a/drivers/s390/block/dasd_devmap.c b/drivers/s390/block/dasd_devmap.c
index 9af02c79ce8a..91cf971f0652 100644
--- a/drivers/s390/block/dasd_devmap.c
+++ b/drivers/s390/block/dasd_devmap.c
@@ -258,8 +258,12 @@ dasd_parse_keyword( char *parsestring ) {
                 return residual_str;
         }
         if (strncmp("nopav", parsestring, length) == 0) {
-                dasd_nopav = 1;
-                MESSAGE(KERN_INFO, "%s", "disable PAV mode");
+                if (MACHINE_IS_VM)
+                        MESSAGE(KERN_INFO, "%s", "'nopav' not supported on VM");
+                else {
+                        dasd_nopav = 1;
+                        MESSAGE(KERN_INFO, "%s", "disable PAV mode");
+                }
                 return residual_str;
         }
         if (strncmp("fixedbuffers", parsestring, length) == 0) {
@@ -523,17 +527,17 @@ dasd_create_device(struct ccw_device *cdev)
 {
         struct dasd_devmap *devmap;
         struct dasd_device *device;
+        unsigned long flags;
         int rc;
 
         devmap = dasd_devmap_from_cdev(cdev);
         if (IS_ERR(devmap))
                 return (void *) devmap;
-        cdev->dev.driver_data = devmap;
 
         device = dasd_alloc_device();
         if (IS_ERR(device))
                 return device;
-        atomic_set(&device->ref_count, 2);
+        atomic_set(&device->ref_count, 3);
 
         spin_lock(&dasd_devmap_lock);
         if (!devmap->device) {
@@ -552,6 +556,11 @@ dasd_create_device(struct ccw_device *cdev)
                 dasd_free_device(device);
                 return ERR_PTR(rc);
         }
+
+        spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
+        cdev->dev.driver_data = device;
+        spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
+
         return device;
 }
 
@@ -569,6 +578,7 @@ dasd_delete_device(struct dasd_device *device)
 {
         struct ccw_device *cdev;
         struct dasd_devmap *devmap;
+        unsigned long flags;
 
         /* First remove device pointer from devmap. */
         devmap = dasd_find_busid(device->cdev->dev.bus_id);
@@ -582,9 +592,16 @@ dasd_delete_device(struct dasd_device *device)
         devmap->device = NULL;
         spin_unlock(&dasd_devmap_lock);
 
-        /* Drop ref_count by 2, one for the devmap reference and
-         * one for the passed reference. */
-        atomic_sub(2, &device->ref_count);
+        /* Disconnect dasd_device structure from ccw_device structure. */
+        spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
+        device->cdev->dev.driver_data = NULL;
+        spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
+
+        /*
+         * Drop ref_count by 3, one for the devmap reference, one for
+         * the cdev reference and one for the passed reference.
+         */
+        atomic_sub(3, &device->ref_count);
 
         /* Wait for reference counter to drop to zero. */
         wait_event(dasd_delete_wq, atomic_read(&device->ref_count) == 0);
@@ -593,9 +610,6 @@ dasd_delete_device(struct dasd_device *device)
         cdev = device->cdev;
         device->cdev = NULL;
 
-        /* Disconnect dasd_devmap structure from ccw_device structure. */
-        cdev->dev.driver_data = NULL;
-
         /* Put ccw_device structure. */
         put_device(&cdev->dev);
 
@@ -615,21 +629,32 @@ dasd_put_device_wake(struct dasd_device *device)
 
 /*
  * Return dasd_device structure associated with cdev.
+ * This function needs to be called with the ccw device
+ * lock held. It can be used from interrupt context.
+ */
+struct dasd_device *
+dasd_device_from_cdev_locked(struct ccw_device *cdev)
+{
+        struct dasd_device *device = cdev->dev.driver_data;
+
+        if (!device)
+                return ERR_PTR(-ENODEV);
+        dasd_get_device(device);
+        return device;
+}
+
+/*
+ * Return dasd_device structure associated with cdev.
  */
 struct dasd_device *
 dasd_device_from_cdev(struct ccw_device *cdev)
 {
-        struct dasd_devmap *devmap;
         struct dasd_device *device;
+        unsigned long flags;
 
-        device = ERR_PTR(-ENODEV);
-        spin_lock(&dasd_devmap_lock);
-        devmap = cdev->dev.driver_data;
-        if (devmap && devmap->device) {
-                device = devmap->device;
-                dasd_get_device(device);
-        }
-        spin_unlock(&dasd_devmap_lock);
+        spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
+        device = dasd_device_from_cdev_locked(cdev);
+        spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
         return device;
 }
 
@@ -730,16 +755,17 @@ static ssize_t
 dasd_discipline_show(struct device *dev, struct device_attribute *attr,
                      char *buf)
 {
-        struct dasd_devmap *devmap;
-        char *dname;
+        struct dasd_device *device;
+        ssize_t len;
 
-        spin_lock(&dasd_devmap_lock);
-        dname = "none";
-        devmap = dev->driver_data;
-        if (devmap && devmap->device && devmap->device->discipline)
-                dname = devmap->device->discipline->name;
-        spin_unlock(&dasd_devmap_lock);
-        return snprintf(buf, PAGE_SIZE, "%s\n", dname);
+        device = dasd_device_from_cdev(to_ccwdev(dev));
+        if (!IS_ERR(device) && device->discipline) {
+                len = snprintf(buf, PAGE_SIZE, "%s\n",
+                               device->discipline->name);
+                dasd_put_device(device);
+        } else
+                len = snprintf(buf, PAGE_SIZE, "none\n");
+        return len;
 }
 
 static DEVICE_ATTR(discipline, 0444, dasd_discipline_show, NULL);