dmaengine: sun6i: Fix memory leaks

The sun6i_dma_prep_memcpy and sun6i_dma_prep_slave_sg functions were both
leaking the descriptor they allocated if an error was happening after a
successful dma_pool_alloc call.

It also fixes a memleak that was happening in the scatter gather list
traversal, that was allocating as much descriptor as there was scatter gather
items, but only freeing the current descriptor if an error was to arise.

Reported-by: Dan Carpenter <[e-mail]>
Signed-off-by: Maxime Ripard <[e-mail]>
Signed-off-by: Vinod Koul <[e-mail]>

drivers/dma/sun6i-dma.c

···
 	v_lli = dma_pool_alloc(sdev->pool, GFP_NOWAIT, &p_lli);
 	if (!v_lli) {
 		dev_err(sdev->slave.dev, "Failed to alloc lli memory\n");
-		kfree(txd);
-		return NULL;
+		goto err_txd_free;
 	}
 
 	ret = sun6i_dma_cfg_lli(v_lli, src, dest, len, sconfig);
···
 
 err_dma_free:
 	dma_pool_free(sdev->pool, v_lli, p_lli);
+err_txd_free:
+	kfree(txd);
 	return NULL;
 }
 
···
 
 	for_each_sg(sgl, sg, sg_len, i) {
 		v_lli = dma_pool_alloc(sdev->pool, GFP_NOWAIT, &p_lli);
-		if (!v_lli) {
-			kfree(txd);
-			return NULL;
-		}
+		if (!v_lli)
+			goto err_lli_free;
 
 		if (dir == DMA_MEM_TO_DEV) {
 			ret = sun6i_dma_cfg_lli(v_lli, sg_dma_address(sg),
 						sconfig->dst_addr, sg_dma_len(sg),
 						sconfig);
 			if (ret)
-				goto err_dma_free;
+				goto err_cur_lli_free;
 
 			v_lli->cfg |= DMA_CHAN_CFG_DST_IO_MODE |
 				DMA_CHAN_CFG_SRC_LINEAR_MODE |
···
 						sg_dma_address(sg), sg_dma_len(sg),
 						sconfig);
 			if (ret)
-				goto err_dma_free;
+				goto err_cur_lli_free;
 
 			v_lli->cfg |= DMA_CHAN_CFG_DST_LINEAR_MODE |
 				DMA_CHAN_CFG_SRC_IO_MODE |
···
 
 	return vchan_tx_prep(&vchan->vc, &txd->vd, flags);
 
-err_dma_free:
+err_cur_lli_free:
 	dma_pool_free(sdev->pool, v_lli, p_lli);
+err_lli_free:
+	for (prev = txd->v_lli; prev; prev = prev->v_lli_next)
+		dma_pool_free(sdev->pool, prev, virt_to_phys(prev));
+	kfree(txd);
 	return NULL;
 }