[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, 5 insertions, 12 deletions

diff --git a/drivers/s390/block/dasd_ioctl.c b/drivers/s390/block/dasd_ioctl.c
index 980c555aa538..789595b3fa09 100644
--- a/drivers/s390/block/dasd_ioctl.c
+++ b/drivers/s390/block/dasd_ioctl.c
@@ -7,7 +7,7 @@
  * Bugreports.to..: <Linux390@de.ibm.com>
  * (C) IBM Corporation, IBM Deutschland Entwicklung GmbH, 1999-2001
  *
- * $Revision: 1.45 $
+ * $Revision: 1.47 $
  *
  * i/o controls for the dasd driver.
  */
@@ -296,7 +296,6 @@ dasd_ioctl_format(struct block_device *bdev, int no, long args)
 {
         struct dasd_device *device;
         struct format_data_t fdata;
-        int feature_ro;
 
         if (!capable(CAP_SYS_ADMIN))
                 return -EACCES;
@@ -308,10 +307,7 @@ dasd_ioctl_format(struct block_device *bdev, int no, long args)
         if (device == NULL)
                 return -ENODEV;
 
-        feature_ro = dasd_get_feature(device->cdev, DASD_FEATURE_READONLY);
-        if (feature_ro < 0)
-                return feature_ro;
-        if (feature_ro)
+        if (device->features & DASD_FEATURE_READONLY)
                 return -EROFS;
         if (copy_from_user(&fdata, (void __user *) args,
                            sizeof (struct format_data_t)))
@@ -384,7 +380,7 @@ dasd_ioctl_information(struct block_device *bdev, int no, long args)
         struct dasd_device *device;
         struct dasd_information2_t *dasd_info;
         unsigned long flags;
-        int rc, feature_ro;
+        int rc;
         struct ccw_device *cdev;
 
         device = bdev->bd_disk->private_data;
@@ -394,10 +390,6 @@ dasd_ioctl_information(struct block_device *bdev, int no, long args)
         if (!device->discipline->fill_info)
                 return -EINVAL;
 
-        feature_ro = dasd_get_feature(device->cdev, DASD_FEATURE_READONLY);
-        if (feature_ro < 0)
-                return feature_ro;
-
         dasd_info = kmalloc(sizeof(struct dasd_information2_t), GFP_KERNEL);
         if (dasd_info == NULL)
                 return -ENOMEM;
@@ -427,7 +419,8 @@ dasd_ioctl_information(struct block_device *bdev, int no, long args)
             (dasd_check_blocksize(device->bp_block)))
                 dasd_info->format = DASD_FORMAT_NONE;
 
-        dasd_info->features |= feature_ro;
+        dasd_info->features |=
+                ((device->features & DASD_FEATURE_READONLY) != 0);
 
         if (device->discipline)
                 memcpy(dasd_info->type, device->discipline->name, 4);