[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, 13 deletions

diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c
index d5f53980749b..8fc891a9d47f 100644
--- a/drivers/s390/block/dasd.c
+++ b/drivers/s390/block/dasd.c
@@ -7,7 +7,7 @@
  * Bugreports.to..: <Linux390@de.ibm.com>
  * (C) IBM Corporation, IBM Deutschland Entwicklung GmbH, 1999-2001
  *
- * $Revision: 1.165 $
+ * $Revision: 1.167 $
  */
 
 #include <linux/config.h>
@@ -1131,17 +1131,13 @@ __dasd_process_blk_queue(struct dasd_device * device)
         request_queue_t *queue;
         struct request *req;
         struct dasd_ccw_req *cqr;
-        int nr_queued, feature_ro;
+        int nr_queued;
 
         queue = device->request_queue;
         /* No queue ? Then there is nothing to do. */
         if (queue == NULL)
                 return;
 
-        feature_ro = dasd_get_feature(device->cdev, DASD_FEATURE_READONLY);
-        if (feature_ro < 0)     /* no devmap */
-                return;
-
         /*
          * We requeue request from the block device queue to the ccw
          * queue only in two states. In state DASD_STATE_READY the
@@ -1162,7 +1158,8 @@ __dasd_process_blk_queue(struct dasd_device * device)
                 nr_queued < DASD_CHANQ_MAX_SIZE) {
                 req = elv_next_request(queue);
 
-                if (feature_ro && rq_data_dir(req) == WRITE) {
+                if (device->features & DASD_FEATURE_READONLY &&
+                    rq_data_dir(req) == WRITE) {
                         DBF_DEV_EVENT(DBF_ERR, device,
                                       "Rejecting write request %p",
                                       req);
@@ -1814,17 +1811,13 @@ dasd_generic_set_online (struct ccw_device *cdev,
 
 {
         struct dasd_device *device;
-        int feature_diag, rc;
+        int rc;
 
         device = dasd_create_device(cdev);
         if (IS_ERR(device))
                 return PTR_ERR(device);
 
-        feature_diag = dasd_get_feature(cdev, DASD_FEATURE_USEDIAG);
-        if (feature_diag < 0)
-                return feature_diag;
-
-        if (feature_diag) {
+        if (device->features & DASD_FEATURE_USEDIAG) {
                 if (!dasd_diag_discipline_pointer) {
                         printk (KERN_WARNING
                                 "dasd_generic couldn't online device %s "