s390/css: stop stsch loop after cc 3

Receiving cc=3 from store subchannel means 2 things:
* the subchannel is not provided
* there are no further subchannels in this subchannel set

With this patch we abort the store subchannel loop after cc=3 (or an
exception) and clear the subsequent bits in the subchannel id set.

Reported-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Acked-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/cio/css.c

@@ -377,7 +377,11 @@ static int css_evaluate_new_subchannel(struct subchannel_id schid, int slow)
 		/* Will be done on the slow path. */
 		return -EAGAIN;
 	}
-	if (stsch_err(schid, &schib) || !css_sch_is_valid(&schib)) {
+	if (stsch_err(schid, &schib)) {
+		/* Subchannel is not provided. */
+		return -ENXIO;
+	}
+	if (!css_sch_is_valid(&schib)) {
 		/* Unusable - ignore. */
 		return 0;
 	}
@@ -536,6 +540,7 @@ static int slow_eval_unknown_fn(struct subchannel_id schid, void *data)
 		case -ENOMEM:
 		case -EIO:
 			/* These should abort looping */
+			idset_sch_del_subseq(slow_subchannel_set, schid);
 			break;
 		default:
 			rc = 0;

drivers/s390/cio/idset.c

@@ -90,6 +90,14 @@ void idset_sch_del(struct idset *set, struct subchannel_id schid)
 	idset_del(set, schid.ssid, schid.sch_no);
 }
 
+/* Clear ids starting from @schid up to end of subchannel set. */
+void idset_sch_del_subseq(struct idset *set, struct subchannel_id schid)
+{
+	int pos = schid.ssid * set->num_id + schid.sch_no;
+
+	bitmap_clear(set->bitmap, pos, set->num_id - schid.sch_no);
+}
+
 int idset_sch_contains(struct idset *set, struct subchannel_id schid)
 {
 	return idset_contains(set, schid.ssid, schid.sch_no);

drivers/s390/cio/idset.h

@@ -1,5 +1,5 @@
 /*
- *    Copyright IBM Corp. 2007
+ *    Copyright IBM Corp. 2007, 2012
  *    Author(s): Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
  */
 
@@ -17,6 +17,7 @@ void idset_fill(struct idset *set);
 struct idset *idset_sch_new(void);
 void idset_sch_add(struct idset *set, struct subchannel_id id);
 void idset_sch_del(struct idset *set, struct subchannel_id id);
+void idset_sch_del_subseq(struct idset *set, struct subchannel_id schid);
 int idset_sch_contains(struct idset *set, struct subchannel_id id);
 int idset_sch_get_first(struct idset *set, struct subchannel_id *id);
 int idset_is_empty(struct idset *set);