dmaengine/ste_dma40: fix memory leak due to prepared descriptors

Prepared descriptors that are not submitted will not be freed. Add
prepared descriptor to a list to be able to release them upon
dmaengine_terminate_all().
Signed-off-by: Per Forlin <per.forlin@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/ste_dma40.c

@@ -177,6 +177,7 @@ struct d40_base;
  * @pending_queue: Submitted jobs, to be issued by issue_pending()
  * @active: Active descriptor.
  * @queue: Queued jobs.
+ * @prepare_queue: Prepared jobs.
  * @dma_cfg: The client configuration of this dma channel.
  * @configured: whether the dma_cfg configuration is valid
  * @base: Pointer to the device instance struct.
@@ -204,6 +205,7 @@ struct d40_chan {
 	struct list_head		 pending_queue;
 	struct list_head		 active;
 	struct list_head		 queue;
+	struct list_head		 prepare_queue;
 	struct stedma40_chan_cfg	 dma_cfg;
 	bool				 configured;
 	struct d40_base			*base;
@@ -833,6 +835,13 @@ static void d40_term_all(struct d40_chan *d40c)
 			d40_desc_free(d40c, d40d);
 		}
 
+	/* Release descriptors in prepare queue */
+	if (!list_empty(&d40c->prepare_queue))
+		list_for_each_entry_safe(d40d, _d,
+					 &d40c->prepare_queue, node) {
+			d40_desc_remove(d40d);
+			d40_desc_free(d40c, d40d);
+		}
 
 	d40c->pending_tx = 0;
 	d40c->busy = false;
@@ -1911,6 +1920,12 @@ d40_prep_sg(struct dma_chan *dchan, struct scatterlist *sg_src,
 		goto err;
 	}
 
+	/*
+	 * add descriptor to the prepare queue in order to be able
+	 * to free them later in terminate_all
+	 */
+	list_add_tail(&desc->node, &chan->prepare_queue);
+
 	spin_unlock_irqrestore(&chan->lock, flags);
 
 	return &desc->txd;
@@ -2400,6 +2415,7 @@ static void __init d40_chan_init(struct d40_base *base, struct dma_device *dma,
 		INIT_LIST_HEAD(&d40c->queue);
 		INIT_LIST_HEAD(&d40c->pending_queue);
 		INIT_LIST_HEAD(&d40c->client);
+		INIT_LIST_HEAD(&d40c->prepare_queue);
 
 		tasklet_init(&d40c->tasklet, dma_tasklet,
 			     (unsigned long) d40c);