DMAENGINE: ste_dma40: fix desc_get

Fix desc_get to alloc a descriptor from the cache if the ones in the
list are waiting for the ack.  Also, memzero the descriptor when
allocated from the list to ensure all fields are cleared.
Acked-by: Jonas Aaberg <jonas.aberg@stericsson.com>
Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/dma/ste_dma40.c

@@ -419,24 +419,29 @@ static void d40_desc_remove(struct d40_desc *d40d)
 
 static struct d40_desc *d40_desc_get(struct d40_chan *d40c)
 {
-	struct d40_desc *d;
-	struct d40_desc *_d;
+	struct d40_desc *desc = NULL;
 
 	if (!list_empty(&d40c->client)) {
+		struct d40_desc *d;
+		struct d40_desc *_d;
+
 		list_for_each_entry_safe(d, _d, &d40c->client, node)
 			if (async_tx_test_ack(&d->txd)) {
 				d40_pool_lli_free(d);
 				d40_desc_remove(d);
+				desc = d;
+				memset(desc, 0, sizeof(*desc));
 				break;
 			}
-	} else {
-		d = kmem_cache_alloc(d40c->base->desc_slab, GFP_NOWAIT);
-		if (d != NULL) {
-			memset(d, 0, sizeof(struct d40_desc));
-			INIT_LIST_HEAD(&d->node);
-		}
 	}
-	return d;
+
+	if (!desc)
+		desc = kmem_cache_zalloc(d40c->base->desc_slab, GFP_NOWAIT);
+
+	if (desc)
+		INIT_LIST_HEAD(&desc->node);
+
+	return desc;
 }
 
 static void d40_desc_free(struct d40_chan *d40c, struct d40_desc *d40d)