[PATCH net] net: stmmac: Stop using a single dma_map() for multiple descriptors

[Suraj Jaiswal <quic_jsuraj@xxxxxxxxxxx>]

Currently same page address is shared
between multiple buffer addresses and causing smmu fault for other
descriptor if address hold by one descriptor got cleaned.
Allocate separate buffer address for each descriptor
for TSO path so that if one descriptor cleared it should not
clean other descriptor address.

Signed-off-by: Suraj Jaiswal <quic_jsuraj@xxxxxxxxxxx>
---

Changes since v2:
- Fixed function description 
- Fixed handling of return value.


 .../net/ethernet/stmicro/stmmac/stmmac_main.c | 63 ++++++++++++-------
 1 file changed, 42 insertions(+), 21 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 83b654b7a9fd..5948774c403f 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -4136,16 +4136,18 @@ static bool stmmac_vlan_insert(struct stmmac_priv *priv, struct sk_buff *skb,
 /**
  *  stmmac_tso_allocator - close entry point of the driver
  *  @priv: driver private structure
- *  @des: buffer start address
+ *  @addr: Contains either skb frag address or skb->data address
  *  @total_len: total length to fill in descriptors
  *  @last_segment: condition for the last descriptor
  *  @queue: TX queue index
+ * @is_skb_frag: condition to check whether skb data is part of fragment or not
  *  Description:
  *  This function fills descriptor and request new descriptors according to
  *  buffer length to fill
+ *  This function returns 0 on success else -ERRNO on fail
  */
-static void stmmac_tso_allocator(struct stmmac_priv *priv, dma_addr_t des,
-				 int total_len, bool last_segment, u32 queue)
+static int stmmac_tso_allocator(struct stmmac_priv *priv, void *addr,
+				int total_len, bool last_segment, u32 queue, bool is_skb_frag)
 {
 	struct stmmac_tx_queue *tx_q = &priv->dma_conf.tx_queue[queue];
 	struct dma_desc *desc;
@@ -4153,6 +4155,8 @@ static void stmmac_tso_allocator(struct stmmac_priv *priv, dma_addr_t des,
 	int tmp_len;
 
 	tmp_len = total_len;
+	unsigned int offset = 0;
+	unsigned char *data = addr;
 
 	while (tmp_len > 0) {
 		dma_addr_t curr_addr;
@@ -4161,20 +4165,44 @@ static void stmmac_tso_allocator(struct stmmac_priv *priv, dma_addr_t des,
 						priv->dma_conf.dma_tx_size);
 		WARN_ON(tx_q->tx_skbuff[tx_q->cur_tx]);
 
+		buff_size = tmp_len >= TSO_MAX_BUFF_SIZE ? TSO_MAX_BUFF_SIZE : tmp_len;
+
 		if (tx_q->tbs & STMMAC_TBS_AVAIL)
 			desc = &tx_q->dma_entx[tx_q->cur_tx].basic;
 		else
 			desc = &tx_q->dma_tx[tx_q->cur_tx];
 
-		curr_addr = des + (total_len - tmp_len);
+		offset = total_len - tmp_len;
+		if (!is_skb_frag) {
+			curr_addr = dma_map_single(priv->device, data + offset, buff_size,
+						   DMA_TO_DEVICE);
+
+			if (dma_mapping_error(priv->device, curr_addr))
+				return -ENOMEM;
+
+			tx_q->tx_skbuff_dma[tx_q->cur_tx].buf = curr_addr;
+			tx_q->tx_skbuff_dma[tx_q->cur_tx].len = buff_size;
+			tx_q->tx_skbuff_dma[tx_q->cur_tx].map_as_page = false;
+			tx_q->tx_skbuff_dma[tx_q->cur_tx].buf_type = STMMAC_TXBUF_T_SKB;
+		} else {
+			curr_addr = skb_frag_dma_map(priv->device, addr, offset,
+						     buff_size,
+						     DMA_TO_DEVICE);
+
+			if (dma_mapping_error(priv->device, curr_addr))
+				return -ENOMEM;
+
+			tx_q->tx_skbuff_dma[tx_q->cur_tx].buf = curr_addr;
+			tx_q->tx_skbuff_dma[tx_q->cur_tx].len = buff_size;
+			tx_q->tx_skbuff_dma[tx_q->cur_tx].map_as_page = true;
+			tx_q->tx_skbuff_dma[tx_q->cur_tx].buf_type = STMMAC_TXBUF_T_SKB;
+		}
+
 		if (priv->dma_cap.addr64 <= 32)
 			desc->des0 = cpu_to_le32(curr_addr);
 		else
 			stmmac_set_desc_addr(priv, desc, curr_addr);
 
-		buff_size = tmp_len >= TSO_MAX_BUFF_SIZE ?
-			    TSO_MAX_BUFF_SIZE : tmp_len;
-
 		stmmac_prepare_tso_tx_desc(priv, desc, 0, buff_size,
 				0, 1,
 				(last_segment) && (tmp_len <= TSO_MAX_BUFF_SIZE),
@@ -4182,6 +4210,7 @@ static void stmmac_tso_allocator(struct stmmac_priv *priv, dma_addr_t des,
 
 		tmp_len -= TSO_MAX_BUFF_SIZE;
 	}
+	return 0;
 }
 
 static void stmmac_flush_tx_descriptors(struct stmmac_priv *priv, int queue)
@@ -4351,25 +4380,17 @@ static netdev_tx_t stmmac_tso_xmit(struct sk_buff *skb, struct net_device *dev)
 		pay_len = 0;
 	}
 
-	stmmac_tso_allocator(priv, des, tmp_pay_len, (nfrags == 0), queue);
+	if (stmmac_tso_allocator(priv, (skb->data + proto_hdr_len),
+				 tmp_pay_len, nfrags == 0, queue, false))
+		goto dma_map_err;
 
 	/* Prepare fragments */
 	for (i = 0; i < nfrags; i++) {
-		const skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+		skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
 
-		des = skb_frag_dma_map(priv->device, frag, 0,
-				       skb_frag_size(frag),
-				       DMA_TO_DEVICE);
-		if (dma_mapping_error(priv->device, des))
+		if (stmmac_tso_allocator(priv, frag, skb_frag_size(frag),
+					 (i == nfrags - 1), queue, true))
 			goto dma_map_err;
-
-		stmmac_tso_allocator(priv, des, skb_frag_size(frag),
-				     (i == nfrags - 1), queue);
-
-		tx_q->tx_skbuff_dma[tx_q->cur_tx].buf = des;
-		tx_q->tx_skbuff_dma[tx_q->cur_tx].len = skb_frag_size(frag);
-		tx_q->tx_skbuff_dma[tx_q->cur_tx].map_as_page = true;
-		tx_q->tx_skbuff_dma[tx_q->cur_tx].buf_type = STMMAC_TXBUF_T_SKB;
 	}
 
 	tx_q->tx_skbuff_dma[tx_q->cur_tx].last_segment = true;
-- 
2.25.1