Date:	Sat, 17 Mar 2012 01:51:00 -0700
From:	Jeff Kirsher <jeffrey.t.kirsher@...el.com>
To:	davem@...emloft.net
Cc:	Alexander Duyck <alexander.h.duyck@...el.com>,
	netdev@...r.kernel.org, gospo@...hat.com, sassmann@...hat.com,
	Jeff Kirsher <jeffrey.t.kirsher@...el.com>
Subject: [net-next 12/12] ixgbe: always write DMA for single_mapped value with skb

From: Alexander Duyck <alexander.h.duyck@...el.com>

This change makes it so that we always write the DMA address for the skb
itself on the same tx_buffer struct that the skb is written on.  This way
we don't need the MAPPED_AS_PAGE flag and we always know it will be the
first DMA value that we will have to unmap.

In addition I have found an issue in which we were leaking a DMA mapping if
the value happened to be 0 which is possible on some platforms.  In order
to resolve that I have updated the transmit path to use the length instead
of the DMA mapping in order to determine if a mapping is actually present.

One other tweak in this patch is that it only writes the olinfo information
on the first descriptor.  As it turns out it isn't necessary to write it
for anything but the first descriptor so there is no need to carry it
forward.

Signed-off-by: Alexander Duyck <alexander.h.duyck@...el.com>
Tested-by: Stephen Ko <stephen.s.ko@...el.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
---
 drivers/net/ethernet/intel/ixgbe/ixgbe.h      |    5 +-
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c |  266 ++++++++++++++-----------
 2 files changed, 153 insertions(+), 118 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe.h b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
index 55f31fe..e0d809d 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe.h
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
@@ -96,7 +96,6 @@
 #define IXGBE_TX_FLAGS_FCOE		(u32)(1 << 5)
 #define IXGBE_TX_FLAGS_FSO		(u32)(1 << 6)
 #define IXGBE_TX_FLAGS_TXSW		(u32)(1 << 7)
-#define IXGBE_TX_FLAGS_MAPPED_AS_PAGE	(u32)(1 << 8)
 #define IXGBE_TX_FLAGS_VLAN_MASK	0xffff0000
 #define IXGBE_TX_FLAGS_VLAN_PRIO_MASK	0xe0000000
 #define IXGBE_TX_FLAGS_VLAN_PRIO_SHIFT  29
@@ -153,8 +152,8 @@ struct ixgbe_tx_buffer {
 	struct sk_buff *skb;
 	unsigned int bytecount;
 	unsigned short gso_segs;
-	dma_addr_t dma;
-	unsigned int length;
+	DEFINE_DMA_UNMAP_ADDR(dma);
+	DEFINE_DMA_UNMAP_LEN(len);
 	u32 tx_flags;
 };
 
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index 40d729e..1d8f9f8 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -289,7 +289,7 @@ static void ixgbe_dump(struct ixgbe_adapter *adapter)
 	struct ixgbe_reg_info *reginfo;
 	int n = 0;
 	struct ixgbe_ring *tx_ring;
-	struct ixgbe_tx_buffer *tx_buffer_info;
+	struct ixgbe_tx_buffer *tx_buffer;
 	union ixgbe_adv_tx_desc *tx_desc;
 	struct my_u0 { u64 a; u64 b; } *u0;
 	struct ixgbe_ring *rx_ring;
@@ -329,14 +329,13 @@ static void ixgbe_dump(struct ixgbe_adapter *adapter)
 	pr_info("Queue [NTU] [NTC] [bi(ntc)->dma  ] leng ntw timestamp\n");
 	for (n = 0; n < adapter->num_tx_queues; n++) {
 		tx_ring = adapter->tx_ring[n];
-		tx_buffer_info =
-			&tx_ring->tx_buffer_info[tx_ring->next_to_clean];
+		tx_buffer = &tx_ring->tx_buffer_info[tx_ring->next_to_clean];
 		pr_info(" %5d %5X %5X %016llX %04X %p %016llX\n",
 			   n, tx_ring->next_to_use, tx_ring->next_to_clean,
-			   (u64)tx_buffer_info->dma,
-			   tx_buffer_info->length,
-			   tx_buffer_info->next_to_watch,
-			   (u64)tx_buffer_info->time_stamp);
+			   (u64)dma_unmap_addr(tx_buffer, dma),
+			   dma_unmap_len(tx_buffer, len),
+			   tx_buffer->next_to_watch,
+			   (u64)tx_buffer->time_stamp);
 	}
 
 	/* Print TX Rings */
@@ -367,17 +366,17 @@ static void ixgbe_dump(struct ixgbe_adapter *adapter)
 
 		for (i = 0; tx_ring->desc && (i < tx_ring->count); i++) {
 			tx_desc = IXGBE_TX_DESC(tx_ring, i);
-			tx_buffer_info = &tx_ring->tx_buffer_info[i];
+			tx_buffer = &tx_ring->tx_buffer_info[i];
 			u0 = (struct my_u0 *)tx_desc;
 			pr_info("T [0x%03X]    %016llX %016llX %016llX"
 				" %04X  %p %016llX %p", i,
 				le64_to_cpu(u0->a),
 				le64_to_cpu(u0->b),
-				(u64)tx_buffer_info->dma,
-				tx_buffer_info->length,
-				tx_buffer_info->next_to_watch,
-				(u64)tx_buffer_info->time_stamp,
-				tx_buffer_info->skb);
+				(u64)dma_unmap_addr(tx_buffer, dma),
+				dma_unmap_len(tx_buffer, len),
+				tx_buffer->next_to_watch,
+				(u64)tx_buffer->time_stamp,
+				tx_buffer->skb);
 			if (i == tx_ring->next_to_use &&
 				i == tx_ring->next_to_clean)
 				pr_cont(" NTC/U\n");
@@ -389,11 +388,13 @@ static void ixgbe_dump(struct ixgbe_adapter *adapter)
 				pr_cont("\n");
 
 			if (netif_msg_pktdata(adapter) &&
-				tx_buffer_info->dma != 0)
+			    dma_unmap_len(tx_buffer, len) != 0)
 				print_hex_dump(KERN_INFO, "",
 					DUMP_PREFIX_ADDRESS, 16, 1,
-					phys_to_virt(tx_buffer_info->dma),
-					tx_buffer_info->length, true);
+					phys_to_virt(dma_unmap_addr(tx_buffer,
+								    dma)),
+					dma_unmap_len(tx_buffer, len),
+					true);
 		}
 	}
 
@@ -579,32 +580,26 @@ static inline void ixgbe_irq_rearm_queues(struct ixgbe_adapter *adapter,
 	}
 }
 
-static inline void ixgbe_unmap_tx_resource(struct ixgbe_ring *ring,
-					   struct ixgbe_tx_buffer *tx_buffer)
+void ixgbe_unmap_and_free_tx_resource(struct ixgbe_ring *ring,
+				      struct ixgbe_tx_buffer *tx_buffer)
 {
-	if (tx_buffer->dma) {
-		if (tx_buffer->tx_flags & IXGBE_TX_FLAGS_MAPPED_AS_PAGE)
-			dma_unmap_page(ring->dev,
-			               tx_buffer->dma,
-			               tx_buffer->length,
-			               DMA_TO_DEVICE);
-		else
+	if (tx_buffer->skb) {
+		dev_kfree_skb_any(tx_buffer->skb);
+		if (dma_unmap_len(tx_buffer, len))
 			dma_unmap_single(ring->dev,
-			                 tx_buffer->dma,
-			                 tx_buffer->length,
-			                 DMA_TO_DEVICE);
+					 dma_unmap_addr(tx_buffer, dma),
+					 dma_unmap_len(tx_buffer, len),
+					 DMA_TO_DEVICE);
+	} else if (dma_unmap_len(tx_buffer, len)) {
+		dma_unmap_page(ring->dev,
+			       dma_unmap_addr(tx_buffer, dma),
+			       dma_unmap_len(tx_buffer, len),
+			       DMA_TO_DEVICE);
 	}
-	tx_buffer->dma = 0;
-}
-
-void ixgbe_unmap_and_free_tx_resource(struct ixgbe_ring *tx_ring,
-				      struct ixgbe_tx_buffer *tx_buffer_info)
-{
-	ixgbe_unmap_tx_resource(tx_ring, tx_buffer_info);
-	if (tx_buffer_info->skb)
-		dev_kfree_skb_any(tx_buffer_info->skb);
-	tx_buffer_info->skb = NULL;
-	/* tx_buffer_info must be completely set up in the transmit path */
+	tx_buffer->next_to_watch = NULL;
+	tx_buffer->skb = NULL;
+	dma_unmap_len_set(tx_buffer, len, 0);
+	/* tx_buffer must be completely set up in the transmit path */
 }
 
 static void ixgbe_update_xoff_received(struct ixgbe_adapter *adapter)
@@ -741,12 +736,16 @@ static bool ixgbe_clean_tx_irq(struct ixgbe_q_vector *q_vector,
 	union ixgbe_adv_tx_desc *tx_desc;
 	unsigned int total_bytes = 0, total_packets = 0;
 	unsigned int budget = q_vector->tx.work_limit;
-	u16 i = tx_ring->next_to_clean;
+	unsigned int i = tx_ring->next_to_clean;
+
+	if (test_bit(__IXGBE_DOWN, &adapter->state))
+		return true;
 
 	tx_buffer = &tx_ring->tx_buffer_info[i];
 	tx_desc = IXGBE_TX_DESC(tx_ring, i);
+	i -= tx_ring->count;
 
-	for (; budget; budget--) {
+	do {
 		union ixgbe_adv_tx_desc *eop_desc = tx_buffer->next_to_watch;
 
 		/* if next_to_watch is not set then there is no work pending */
@@ -770,27 +769,55 @@ static bool ixgbe_clean_tx_irq(struct ixgbe_q_vector *q_vector,
 		/* free the skb */
 		dev_kfree_skb_any(tx_buffer->skb);
 
+		/* unmap skb header data */
+		dma_unmap_single(tx_ring->dev,
+				 dma_unmap_addr(tx_buffer, dma),
+				 dma_unmap_len(tx_buffer, len),
+				 DMA_TO_DEVICE);
+
 		/* clear tx_buffer data */
 		tx_buffer->skb = NULL;
+		dma_unmap_len_set(tx_buffer, len, 0);
 
-		do {
-			ixgbe_unmap_tx_resource(tx_ring, tx_buffer);
-			if (likely(tx_desc == eop_desc))
-				eop_desc = NULL;
-
+		/* unmap remaining buffers */
+		while (tx_desc != eop_desc) {
 			tx_buffer++;
 			tx_desc++;
 			i++;
-			if (unlikely(i == tx_ring->count)) {
-				i = 0;
-
+			if (unlikely(!i)) {
+				i -= tx_ring->count;
 				tx_buffer = tx_ring->tx_buffer_info;
 				tx_desc = IXGBE_TX_DESC(tx_ring, 0);
 			}
 
-		} while (eop_desc);
-	}
+			/* unmap any remaining paged data */
+			if (dma_unmap_len(tx_buffer, len)) {
+				dma_unmap_page(tx_ring->dev,
+					       dma_unmap_addr(tx_buffer, dma),
+					       dma_unmap_len(tx_buffer, len),
+					       DMA_TO_DEVICE);
+				dma_unmap_len_set(tx_buffer, len, 0);
+			}
+		}
+
+		/* move us one more past the eop_desc for start of next pkt */
+		tx_buffer++;
+		tx_desc++;
+		i++;
+		if (unlikely(!i)) {
+			i -= tx_ring->count;
+			tx_buffer = tx_ring->tx_buffer_info;
+			tx_desc = IXGBE_TX_DESC(tx_ring, 0);
+		}
+
+		/* issue prefetch for next Tx descriptor */
+		prefetch(tx_desc);
 
+		/* update budget accounting */
+		budget--;
+	} while (likely(budget));
+
+	i += tx_ring->count;
 	tx_ring->next_to_clean = i;
 	u64_stats_update_begin(&tx_ring->syncp);
 	tx_ring->stats.bytes += total_bytes;
@@ -802,7 +829,6 @@ static bool ixgbe_clean_tx_irq(struct ixgbe_q_vector *q_vector,
 	if (check_for_tx_hang(tx_ring) && ixgbe_check_tx_hang(tx_ring)) {
 		/* schedule immediate reset if we believe we hung */
 		struct ixgbe_hw *hw = &adapter->hw;
-		tx_desc = IXGBE_TX_DESC(tx_ring, i);
 		e_err(drv, "Detected Tx Unit Hang\n"
 			"  Tx Queue             <%d>\n"
 			"  TDH, TDT             <%x>, <%x>\n"
@@ -840,9 +866,11 @@ static bool ixgbe_clean_tx_irq(struct ixgbe_q_vector *q_vector,
 		 * sees the new next_to_clean.
 		 */
 		smp_mb();
-		if (__netif_subqueue_stopped(tx_ring->netdev, tx_ring->queue_index) &&
-		    !test_bit(__IXGBE_DOWN, &adapter->state)) {
-			netif_wake_subqueue(tx_ring->netdev, tx_ring->queue_index);
+		if (__netif_subqueue_stopped(tx_ring->netdev,
+					     tx_ring->queue_index)
+		    && !test_bit(__IXGBE_DOWN, &adapter->state)) {
+			netif_wake_subqueue(tx_ring->netdev,
+					    tx_ring->queue_index);
 			++tx_ring->tx_stats.restart_queue;
 		}
 	}
@@ -6707,7 +6735,8 @@ static __le32 ixgbe_tx_cmd_type(u32 tx_flags)
 	return cmd_type;
 }
 
-static __le32 ixgbe_tx_olinfo_status(u32 tx_flags, unsigned int paylen)
+static void ixgbe_tx_olinfo_status(union ixgbe_adv_tx_desc *tx_desc,
+				   u32 tx_flags, unsigned int paylen)
 {
 	__le32 olinfo_status = cpu_to_le32(paylen << IXGBE_ADVTXD_PAYLEN_SHIFT);
 
@@ -6738,7 +6767,7 @@ static __le32 ixgbe_tx_olinfo_status(u32 tx_flags, unsigned int paylen)
 #endif
 		olinfo_status |= cpu_to_le32(IXGBE_ADVTXD_CC);
 
-	return olinfo_status;
+	tx_desc->read.olinfo_status = olinfo_status;
 }
 
 #define IXGBE_TXD_CMD (IXGBE_TXD_CMD_EOP | \
@@ -6749,103 +6778,102 @@ static void ixgbe_tx_map(struct ixgbe_ring *tx_ring,
 			 u32 tx_flags,
 			 const u8 hdr_len)
 {
+	dma_addr_t dma;
 	struct sk_buff *skb = first->skb;
-	struct device *dev = tx_ring->dev;
-	struct ixgbe_tx_buffer *tx_buffer_info;
+	struct ixgbe_tx_buffer *tx_buffer;
 	union ixgbe_adv_tx_desc *tx_desc;
-	dma_addr_t dma;
-	__le32 cmd_type, olinfo_status;
-	struct skb_frag_struct *frag;
-	unsigned int f = 0;
+	struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[0];
 	unsigned int data_len = skb->data_len;
 	unsigned int size = skb_headlen(skb);
-	u32 offset = 0;
-	u32 paylen = skb->len - hdr_len;
+	unsigned int paylen = skb->len - hdr_len;
+	__le32 cmd_type;
 	u16 i = tx_ring->next_to_use;
 
+	tx_desc = IXGBE_TX_DESC(tx_ring, i);
+
+	ixgbe_tx_olinfo_status(tx_desc, tx_flags, paylen);
+	cmd_type = ixgbe_tx_cmd_type(tx_flags);
+
 #ifdef IXGBE_FCOE
 	if (tx_flags & IXGBE_TX_FLAGS_FCOE) {
-		if (data_len >= sizeof(struct fcoe_crc_eof)) {
-			data_len -= sizeof(struct fcoe_crc_eof);
-		} else {
+		if (data_len < sizeof(struct fcoe_crc_eof)) {
 			size -= sizeof(struct fcoe_crc_eof) - data_len;
 			data_len = 0;
+		} else {
+			data_len -= sizeof(struct fcoe_crc_eof);
 		}
 	}
 
 #endif
-	dma = dma_map_single(dev, skb->data, size, DMA_TO_DEVICE);
-	if (dma_mapping_error(dev, dma))
+	dma = dma_map_single(tx_ring->dev, skb->data, size, DMA_TO_DEVICE);
+	if (dma_mapping_error(tx_ring->dev, dma))
 		goto dma_error;
 
-	cmd_type = ixgbe_tx_cmd_type(tx_flags);
-	olinfo_status = ixgbe_tx_olinfo_status(tx_flags, paylen);
+	/* record length, and DMA address */
+	dma_unmap_len_set(first, len, size);
+	dma_unmap_addr_set(first, dma, dma);
+	first->tx_flags = tx_flags;
 
-	tx_desc = IXGBE_TX_DESC(tx_ring, i);
+	tx_desc->read.buffer_addr = cpu_to_le64(dma);
 
 	for (;;) {
-		while (size > IXGBE_MAX_DATA_PER_TXD) {
-			tx_desc->read.buffer_addr = cpu_to_le64(dma + offset);
+		while (unlikely(size > IXGBE_MAX_DATA_PER_TXD)) {
 			tx_desc->read.cmd_type_len =
 				cmd_type | cpu_to_le32(IXGBE_MAX_DATA_PER_TXD);
-			tx_desc->read.olinfo_status = olinfo_status;
-
-			offset += IXGBE_MAX_DATA_PER_TXD;
-			size -= IXGBE_MAX_DATA_PER_TXD;
 
-			tx_desc++;
 			i++;
+			tx_desc++;
 			if (i == tx_ring->count) {
 				tx_desc = IXGBE_TX_DESC(tx_ring, 0);
 				i = 0;
 			}
+
+			dma += IXGBE_MAX_DATA_PER_TXD;
+			size -= IXGBE_MAX_DATA_PER_TXD;
+
+			tx_desc->read.buffer_addr = cpu_to_le64(dma);
+			tx_desc->read.olinfo_status = 0;
 		}
 
-		tx_buffer_info = &tx_ring->tx_buffer_info[i];
-		tx_buffer_info->length = offset + size;
-		tx_buffer_info->tx_flags = tx_flags;
-		tx_buffer_info->dma = dma;
+		if (likely(!data_len))
+			break;
 
-		tx_desc->read.buffer_addr = cpu_to_le64(dma + offset);
 		if (unlikely(skb->no_fcs))
 			cmd_type &= ~(cpu_to_le32(IXGBE_ADVTXD_DCMD_IFCS));
 		tx_desc->read.cmd_type_len = cmd_type | cpu_to_le32(size);
-		tx_desc->read.olinfo_status = olinfo_status;
 
-		if (!data_len)
-			break;
+		i++;
+		tx_desc++;
+		if (i == tx_ring->count) {
+			tx_desc = IXGBE_TX_DESC(tx_ring, 0);
+			i = 0;
+		}
 
-		frag = &skb_shinfo(skb)->frags[f];
 #ifdef IXGBE_FCOE
 		size = min_t(unsigned int, data_len, skb_frag_size(frag));
 #else
 		size = skb_frag_size(frag);
 #endif
 		data_len -= size;
-		f++;
 
-		offset = 0;
-		tx_flags |= IXGBE_TX_FLAGS_MAPPED_AS_PAGE;
-
-		dma = skb_frag_dma_map(dev, frag, 0, size, DMA_TO_DEVICE);
-		if (dma_mapping_error(dev, dma))
+		dma = skb_frag_dma_map(tx_ring->dev, frag, 0, size,
+				       DMA_TO_DEVICE);
+		if (dma_mapping_error(tx_ring->dev, dma))
 			goto dma_error;
 
-		tx_desc++;
-		i++;
-		if (i == tx_ring->count) {
-			tx_desc = IXGBE_TX_DESC(tx_ring, 0);
-			i = 0;
-		}
-	}
+		tx_buffer = &tx_ring->tx_buffer_info[i];
+		dma_unmap_len_set(tx_buffer, len, size);
+		dma_unmap_addr_set(tx_buffer, dma, dma);
 
-	tx_desc->read.cmd_type_len |= cpu_to_le32(IXGBE_TXD_CMD);
+		tx_desc->read.buffer_addr = cpu_to_le64(dma);
+		tx_desc->read.olinfo_status = 0;
 
-	i++;
-	if (i == tx_ring->count)
-		i = 0;
+		frag++;
+	}
 
-	tx_ring->next_to_use = i;
+	/* write last descriptor with RS and EOP bits */
+	cmd_type |= cpu_to_le32(size) | cpu_to_le32(IXGBE_TXD_CMD);
+	tx_desc->read.cmd_type_len = cmd_type;
 
 	netdev_tx_sent_queue(txring_txq(tx_ring), first->bytecount);
 
@@ -6853,28 +6881,36 @@ static void ixgbe_tx_map(struct ixgbe_ring *tx_ring,
 	first->time_stamp = jiffies;
 
 	/*
-	 * Force memory writes to complete before letting h/w
-	 * know there are new descriptors to fetch.  (Only
-	 * applicable for weak-ordered memory model archs,
-	 * such as IA-64).
+	 * Force memory writes to complete before letting h/w know there
+	 * are new descriptors to fetch.  (Only applicable for weak-ordered
+	 * memory model archs, such as IA-64).
+	 *
+	 * We also need this memory barrier to make certain all of the
+	 * status bits have been updated before next_to_watch is written.
 	 */
 	wmb();
 
 	/* set next_to_watch value indicating a packet is present */
 	first->next_to_watch = tx_desc;
 
+	i++;
+	if (i == tx_ring->count)
+		i = 0;
+
+	tx_ring->next_to_use = i;
+
 	/* notify HW of packet */
 	writel(i, tx_ring->tail);
 
 	return;
 dma_error:
-	dev_err(dev, "TX DMA map failed\n");
+	dev_err(tx_ring->dev, "TX DMA map failed\n");
 
 	/* clear dma mappings for failed tx_buffer_info map */
 	for (;;) {
-		tx_buffer_info = &tx_ring->tx_buffer_info[i];
-		ixgbe_unmap_and_free_tx_resource(tx_ring, tx_buffer_info);
-		if (tx_buffer_info == first)
+		tx_buffer = &tx_ring->tx_buffer_info[i];
+		ixgbe_unmap_and_free_tx_resource(tx_ring, tx_buffer);
+		if (tx_buffer == first)
 			break;
 		if (i == 0)
 			i = tx_ring->count;
-- 
1.7.7.6

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