[S390] qdio: remove memset hack

Remove memset hack that relied on the layout of struct qdio_q
to avoid deletion of the slib pointer.
Signed-off-by: NJan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/cio/qdio.h

@@ -296,10 +296,8 @@ struct qdio_q {
 	struct qdio_irq *irq_ptr;
 	struct sl *sl;
 	/*
-	 * Warning: Leave this member at the end so it won't be cleared in
-	 * qdio_fill_qs. A page is allocated under this pointer and used for
-	 * slib and sl. slib is 2048 bytes big and sl points to offset
-	 * PAGE_SIZE / 2.
+	 * A page is allocated under this pointer and used for slib and sl.
+	 * slib is 2048 bytes big and sl points to offset PAGE_SIZE / 2.
 	 */
 	struct slib *slib;
 } __attribute__ ((aligned(256)));

drivers/s390/cio/qdio_setup.c

@@ -106,10 +106,12 @@ int qdio_allocate_qs(struct qdio_irq *irq_ptr, int nr_input_qs, int nr_output_qs
 static void setup_queues_misc(struct qdio_q *q, struct qdio_irq *irq_ptr,
 			      qdio_handler_t *handler, int i)
 {
-	/* must be cleared by every qdio_establish */
-	memset(q, 0, ((char *)&q->slib) - ((char *)q));
-	memset(q->slib, 0, PAGE_SIZE);
+	struct slib *slib = q->slib;
 
+	/* queue must be cleared for qdio_establish */
+	memset(q, 0, sizeof(*q));
+	memset(slib, 0, PAGE_SIZE);
+	q->slib = slib;
 	q->irq_ptr = irq_ptr;
 	q->mask = 1 << (31 - i);
 	q->nr = i;