i40e: Quick refactor to start moving data off stack and into Tx buffer info

This patch does some quick work to pull some of the data off of the stack
and hopefully start storing it in the Tx buffer info section of the Tx
ring.  Ideally we should be moving away from having to store much of
anything on the stack and can just maintain it all in the descriptor rings.

Change-ID: I4b4715ea1920e122502482b3f9e56a9a6cb1e9fe
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/i40e/i40e_txrx.c

@@ -2251,14 +2251,16 @@ out:
 
 /**
  * i40e_tso - set up the tso context descriptor
- * @skb:      ptr to the skb we're sending
+ * @first:    pointer to first Tx buffer for xmit
  * @hdr_len:  ptr to the size of the packet header
  * @cd_type_cmd_tso_mss: Quad Word 1
  *
  * Returns 0 if no TSO can happen, 1 if tso is going, or error
  **/
-static int i40e_tso(struct sk_buff *skb, u8 *hdr_len, u64 *cd_type_cmd_tso_mss)
+static int i40e_tso(struct i40e_tx_buffer *first, u8 *hdr_len,
+		    u64 *cd_type_cmd_tso_mss)
 {
+	struct sk_buff *skb = first->skb;
 	u64 cd_cmd, cd_tso_len, cd_mss;
 	union {
 		struct iphdr *v4;
@@ -2271,6 +2273,7 @@ static int i40e_tso(struct sk_buff *skb, u8 *hdr_len, u64 *cd_type_cmd_tso_mss)
 		unsigned char *hdr;
 	} l4;
 	u32 paylen, l4_offset;
+	u16 gso_segs, gso_size;
 	int err;
 
 	if (skb->ip_summed != CHECKSUM_PARTIAL)
@@ -2335,10 +2338,18 @@ static int i40e_tso(struct sk_buff *skb, u8 *hdr_len, u64 *cd_type_cmd_tso_mss)
 	/* compute length of segmentation header */
 	*hdr_len = (l4.tcp->doff * 4) + l4_offset;
 
+	/* pull values out of skb_shinfo */
+	gso_size = skb_shinfo(skb)->gso_size;
+	gso_segs = skb_shinfo(skb)->gso_segs;
+
+	/* update GSO size and bytecount with header size */
+	first->gso_segs = gso_segs;
+	first->bytecount += (first->gso_segs - 1) * *hdr_len;
+
 	/* find the field values */
 	cd_cmd = I40E_TX_CTX_DESC_TSO;
 	cd_tso_len = skb->len - *hdr_len;
-	cd_mss = skb_shinfo(skb)->gso_size;
+	cd_mss = gso_size;
 	*cd_type_cmd_tso_mss |= (cd_cmd << I40E_TXD_CTX_QW1_CMD_SHIFT) |
 				(cd_tso_len << I40E_TXD_CTX_QW1_TSO_LEN_SHIFT) |
 				(cd_mss << I40E_TXD_CTX_QW1_MSS_SHIFT);
@@ -2699,7 +2710,6 @@ static inline void i40e_tx_map(struct i40e_ring *tx_ring, struct sk_buff *skb,
 	u16 i = tx_ring->next_to_use;
 	u32 td_tag = 0;
 	dma_addr_t dma;
-	u16 gso_segs;
 	u16 desc_count = 1;
 
 	if (tx_flags & I40E_TX_FLAGS_HW_VLAN) {
@@ -2708,15 +2718,6 @@ static inline void i40e_tx_map(struct i40e_ring *tx_ring, struct sk_buff *skb,
 			 I40E_TX_FLAGS_VLAN_SHIFT;
 	}
 
-	if (tx_flags & (I40E_TX_FLAGS_TSO | I40E_TX_FLAGS_FSO))
-		gso_segs = skb_shinfo(skb)->gso_segs;
-	else
-		gso_segs = 1;
-
-	/* multiply data chunks by size of headers */
-	first->bytecount = skb->len - hdr_len + (gso_segs * hdr_len);
-	first->gso_segs = gso_segs;
-	first->skb = skb;
 	first->tx_flags = tx_flags;
 
 	dma = dma_map_single(tx_ring->dev, skb->data, size, DMA_TO_DEVICE);
@@ -2902,8 +2903,10 @@ static netdev_tx_t i40e_xmit_frame_ring(struct sk_buff *skb,
 
 	count = i40e_xmit_descriptor_count(skb);
 	if (i40e_chk_linearize(skb, count)) {
-		if (__skb_linearize(skb))
-			goto out_drop;
+		if (__skb_linearize(skb)) {
+			dev_kfree_skb_any(skb);
+			return NETDEV_TX_OK;
+		}
 		count = i40e_txd_use_count(skb->len);
 		tx_ring->tx_stats.tx_linearize++;
 	}
@@ -2919,6 +2922,12 @@ static netdev_tx_t i40e_xmit_frame_ring(struct sk_buff *skb,
 		return NETDEV_TX_BUSY;
 	}
 
+	/* record the location of the first descriptor for this packet */
+	first = &tx_ring->tx_bi[tx_ring->next_to_use];
+	first->skb = skb;
+	first->bytecount = skb->len;
+	first->gso_segs = 1;
+
 	/* prepare the xmit flags */
 	if (i40e_tx_prepare_vlan_flags(skb, tx_ring, &tx_flags))
 		goto out_drop;
@@ -2926,16 +2935,13 @@ static netdev_tx_t i40e_xmit_frame_ring(struct sk_buff *skb,
 	/* obtain protocol of skb */
 	protocol = vlan_get_protocol(skb);
 
-	/* record the location of the first descriptor for this packet */
-	first = &tx_ring->tx_bi[tx_ring->next_to_use];
-
 	/* setup IPv4/IPv6 offloads */
 	if (protocol == htons(ETH_P_IP))
 		tx_flags |= I40E_TX_FLAGS_IPV4;
 	else if (protocol == htons(ETH_P_IPV6))
 		tx_flags |= I40E_TX_FLAGS_IPV6;
 
-	tso = i40e_tso(skb, &hdr_len, &cd_type_cmd_tso_mss);
+	tso = i40e_tso(first, &hdr_len, &cd_type_cmd_tso_mss);
 
 	if (tso < 0)
 		goto out_drop;
@@ -2973,7 +2979,8 @@ static netdev_tx_t i40e_xmit_frame_ring(struct sk_buff *skb,
 	return NETDEV_TX_OK;
 
 out_drop:
-	dev_kfree_skb_any(skb);
+	dev_kfree_skb_any(first->skb);
+	first->skb = NULL;
 	return NETDEV_TX_OK;
 }
 

drivers/net/ethernet/intel/i40evf/i40e_txrx.c

@@ -1549,14 +1549,16 @@ out:
 
 /**
  * i40e_tso - set up the tso context descriptor
- * @skb:      ptr to the skb we're sending
+ * @first:    pointer to first Tx buffer for xmit
  * @hdr_len:  ptr to the size of the packet header
  * @cd_type_cmd_tso_mss: Quad Word 1
  *
  * Returns 0 if no TSO can happen, 1 if tso is going, or error
  **/
-static int i40e_tso(struct sk_buff *skb, u8 *hdr_len, u64 *cd_type_cmd_tso_mss)
+static int i40e_tso(struct i40e_tx_buffer *first, u8 *hdr_len,
+		    u64 *cd_type_cmd_tso_mss)
 {
+	struct sk_buff *skb = first->skb;
 	u64 cd_cmd, cd_tso_len, cd_mss;
 	union {
 		struct iphdr *v4;
@@ -1569,6 +1571,7 @@ static int i40e_tso(struct sk_buff *skb, u8 *hdr_len, u64 *cd_type_cmd_tso_mss)
 		unsigned char *hdr;
 	} l4;
 	u32 paylen, l4_offset;
+	u16 gso_segs, gso_size;
 	int err;
 
 	if (skb->ip_summed != CHECKSUM_PARTIAL)
@@ -1633,10 +1636,18 @@ static int i40e_tso(struct sk_buff *skb, u8 *hdr_len, u64 *cd_type_cmd_tso_mss)
 	/* compute length of segmentation header */
 	*hdr_len = (l4.tcp->doff * 4) + l4_offset;
 
+	/* pull values out of skb_shinfo */
+	gso_size = skb_shinfo(skb)->gso_size;
+	gso_segs = skb_shinfo(skb)->gso_segs;
+
+	/* update GSO size and bytecount with header size */
+	first->gso_segs = gso_segs;
+	first->bytecount += (first->gso_segs - 1) * *hdr_len;
+
 	/* find the field values */
 	cd_cmd = I40E_TX_CTX_DESC_TSO;
 	cd_tso_len = skb->len - *hdr_len;
-	cd_mss = skb_shinfo(skb)->gso_size;
+	cd_mss = gso_size;
 	*cd_type_cmd_tso_mss |= (cd_cmd << I40E_TXD_CTX_QW1_CMD_SHIFT) |
 				(cd_tso_len << I40E_TXD_CTX_QW1_TSO_LEN_SHIFT) |
 				(cd_mss << I40E_TXD_CTX_QW1_MSS_SHIFT);
@@ -1949,7 +1960,6 @@ static inline void i40evf_tx_map(struct i40e_ring *tx_ring, struct sk_buff *skb,
 	u16 i = tx_ring->next_to_use;
 	u32 td_tag = 0;
 	dma_addr_t dma;
-	u16 gso_segs;
 	u16 desc_count = 1;
 
 	if (tx_flags & I40E_TX_FLAGS_HW_VLAN) {
@@ -1958,15 +1968,6 @@ static inline void i40evf_tx_map(struct i40e_ring *tx_ring, struct sk_buff *skb,
 			 I40E_TX_FLAGS_VLAN_SHIFT;
 	}
 
-	if (tx_flags & (I40E_TX_FLAGS_TSO | I40E_TX_FLAGS_FSO))
-		gso_segs = skb_shinfo(skb)->gso_segs;
-	else
-		gso_segs = 1;
-
-	/* multiply data chunks by size of headers */
-	first->bytecount = skb->len - hdr_len + (gso_segs * hdr_len);
-	first->gso_segs = gso_segs;
-	first->skb = skb;
 	first->tx_flags = tx_flags;
 
 	dma = dma_map_single(tx_ring->dev, skb->data, size, DMA_TO_DEVICE);
@@ -2151,8 +2152,10 @@ static netdev_tx_t i40e_xmit_frame_ring(struct sk_buff *skb,
 
 	count = i40e_xmit_descriptor_count(skb);
 	if (i40e_chk_linearize(skb, count)) {
-		if (__skb_linearize(skb))
-			goto out_drop;
+		if (__skb_linearize(skb)) {
+			dev_kfree_skb_any(skb);
+			return NETDEV_TX_OK;
+		}
 		count = i40e_txd_use_count(skb->len);
 		tx_ring->tx_stats.tx_linearize++;
 	}
@@ -2168,6 +2171,12 @@ static netdev_tx_t i40e_xmit_frame_ring(struct sk_buff *skb,
 		return NETDEV_TX_BUSY;
 	}
 
+	/* record the location of the first descriptor for this packet */
+	first = &tx_ring->tx_bi[tx_ring->next_to_use];
+	first->skb = skb;
+	first->bytecount = skb->len;
+	first->gso_segs = 1;
+
 	/* prepare the xmit flags */
 	if (i40evf_tx_prepare_vlan_flags(skb, tx_ring, &tx_flags))
 		goto out_drop;
@@ -2175,16 +2184,13 @@ static netdev_tx_t i40e_xmit_frame_ring(struct sk_buff *skb,
 	/* obtain protocol of skb */
 	protocol = vlan_get_protocol(skb);
 
-	/* record the location of the first descriptor for this packet */
-	first = &tx_ring->tx_bi[tx_ring->next_to_use];
-
 	/* setup IPv4/IPv6 offloads */
 	if (protocol == htons(ETH_P_IP))
 		tx_flags |= I40E_TX_FLAGS_IPV4;
 	else if (protocol == htons(ETH_P_IPV6))
 		tx_flags |= I40E_TX_FLAGS_IPV6;
 
-	tso = i40e_tso(skb, &hdr_len, &cd_type_cmd_tso_mss);
+	tso = i40e_tso(first, &hdr_len, &cd_type_cmd_tso_mss);
 
 	if (tso < 0)
 		goto out_drop;
@@ -2211,7 +2217,8 @@ static netdev_tx_t i40e_xmit_frame_ring(struct sk_buff *skb,
 	return NETDEV_TX_OK;
 
 out_drop:
-	dev_kfree_skb_any(skb);
+	dev_kfree_skb_any(first->skb);
+	first->skb = NULL;
 	return NETDEV_TX_OK;
 }