[PATCH] s390: deadlock in dasd_devmap

Reintroduce a read-only copy of the devmap features in the device struct.
This is necessary to solve a deadlock on the dasd_devmap_lock which is
acquired by dasd_get_features called from the dasd tasklet.  The current
implementation of devmap doesn't allow to call any devmap function from
interrupt or softirq context.

Signed-off-by: Horst Hummel <horst.hummel@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 6 insertions, 2 deletions

diff --git a/drivers/s390/block/dasd_devmap.c b/drivers/s390/block/dasd_devmap.c
index d948566bb24a..bda896d9d788 100644
--- a/drivers/s390/block/dasd_devmap.c
+++ b/drivers/s390/block/dasd_devmap.c
@@ -11,7 +11,7 @@
  * functions may not be called from interrupt context. In particular
  * dasd_get_device is a no-no from interrupt context.
  *
- * $Revision: 1.40 $
+ * $Revision: 1.43 $
  */
 
 #include <linux/config.h>
@@ -513,6 +513,7 @@ dasd_create_device(struct ccw_device *cdev)
         if (!devmap->device) {
                 devmap->device = device;
                 device->devindex = devmap->devindex;
+                device->features = devmap->features;
                 get_device(&cdev->dev);
                 device->cdev = cdev;
                 rc = 0;
@@ -643,6 +644,8 @@ dasd_ro_store(struct device *dev, struct device_attribute *attr, const char *buf
                 devmap->features |= DASD_FEATURE_READONLY;
         else
                 devmap->features &= ~DASD_FEATURE_READONLY;
+        if (devmap->device)
+                devmap->device->features = devmap->features;
         if (devmap->device && devmap->device->gdp)
                 set_disk_ro(devmap->device->gdp, ro_flag);
         spin_unlock(&dasd_devmap_lock);
@@ -758,7 +761,8 @@ dasd_set_feature(struct ccw_device *cdev, int feature, int flag)
                 devmap->features |= feature;
         else
                 devmap->features &= ~feature;
-
+        if (devmap->device)
+                devmap->device->features = devmap->features;
         spin_unlock(&dasd_devmap_lock);
         return 0;
 }