net: hns3: fix for not unmapping TX buffer correctly

When a big TX buffer is sent using multi BD, the driver maps the
whole TX buffer, and unmaps it using info in desc_cb corresponding
to each BD, but only the info in the desc_cb of first BD is correct,
other info in desc_cb is wrong, which causes TX unmapping problem
when SMMU is on.

Only set the mapping and freeing info in the desc_cb of first BD to
fix this problem, because the TX buffer only need to be unmapped and
freed once.

Fixes: 1e8a7977("net: hns3: add handling for big TX fragment")
Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: Huzhong Tan <tanhuazhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/hisilicon/hns3/hns3_enet.c

@@ -1118,12 +1118,12 @@ static int hns3_fill_desc(struct hns3_enet_ring *ring, void *priv,
 		return -ENOMEM;
 	}
 
+	desc_cb->priv = priv;
 	desc_cb->length = size;
+	desc_cb->dma = dma;
+	desc_cb->type = type;
 
 	if (likely(size <= HNS3_MAX_BD_SIZE)) {
-		desc_cb->priv = priv;
-		desc_cb->dma = dma;
-		desc_cb->type = type;
 		desc->addr = cpu_to_le64(dma);
 		desc->tx.send_size = cpu_to_le16(size);
 		desc->tx.bdtp_fe_sc_vld_ra_ri =
@@ -1140,13 +1140,6 @@ static int hns3_fill_desc(struct hns3_enet_ring *ring, void *priv,
 
 	/* When frag size is bigger than hardware limit, split this frag */
 	for (k = 0; k < frag_buf_num; k++) {
-		/* The txbd's baseinfo of DESC_TYPE_PAGE & DESC_TYPE_SKB */
-		desc_cb->priv = priv;
-		desc_cb->dma = dma + HNS3_MAX_BD_SIZE * k;
-		desc_cb->type = ((type == DESC_TYPE_FRAGLIST_SKB ||
-				  type == DESC_TYPE_SKB) && !k) ?
-				type : DESC_TYPE_PAGE;
-
 		/* now, fill the descriptor */
 		desc->addr = cpu_to_le64(dma + HNS3_MAX_BD_SIZE * k);
 		desc->tx.send_size = cpu_to_le16((k == frag_buf_num - 1) ?
@@ -1158,7 +1151,6 @@ static int hns3_fill_desc(struct hns3_enet_ring *ring, void *priv,
 		/* move ring pointer to next */
 		ring_ptr_move_fw(ring, next_to_use);
 
-		desc_cb = &ring->desc_cb[ring->next_to_use];
 		desc = &ring->desc[ring->next_to_use];
 	}