netdev - [PATCH 01/22] e1000: Fix early TSO completion

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Date:	Fri, 08 Dec 2006 15:02:46 -0800
From:	"Kok, Auke" <auke-jan.h.kok@...el.com>
To:	"Garzik, Jeff" <jgarzik@...ox.com>
Cc:	netdev@...r.kernel.org,
	"Brandeburg, Jesse" <jesse.brandeburg@...el.com>,
	"Kok, Auke" <auke-jan.h.kok@...el.com>,
	"Kok, Auke" <auke@...-projects.org>,
	"Ronciak, John" <john.ronciak@...el.com>
Subject: [PATCH 01/22] e1000: Fix early TSO completion


This fix was already merged in commit 96f9c2e277768099479fbed7c3b69c294b1fadef
but reverted in commit 989316ddfeafd0e8fb51a4d811383769ad62637a. After
stresstesting we found that the fix does not add new regressions and
works around a TX hang spotted by several users.

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@...el.com>
Signed-off-by: Auke Kok <auke-jan.h.kok@...el.com>
---

 drivers/net/ixgb/ixgb_main.c |   21 +++++++++++++++++++--
 1 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ixgb/ixgb_main.c b/drivers/net/ixgb/ixgb_main.c
index e628126..ebc9d71 100644
--- a/drivers/net/ixgb/ixgb_main.c
+++ b/drivers/net/ixgb/ixgb_main.c
@@ -1287,6 +1287,9 @@ ixgb_tx_map(struct ixgb_adapter *adapter
 	struct ixgb_buffer *buffer_info;
 	int len = skb->len;
 	unsigned int offset = 0, size, count = 0, i;
+#ifdef NETIF_F_TSO
+	unsigned int mss = skb_shinfo(skb)->gso_size;
+#endif
 
 	unsigned int nr_frags = skb_shinfo(skb)->nr_frags;
 	unsigned int f;
@@ -1298,6 +1301,12 @@ ixgb_tx_map(struct ixgb_adapter *adapter
 	while(len) {
 		buffer_info = &tx_ring->buffer_info[i];
 		size = min(len, IXGB_MAX_DATA_PER_TXD);
+#ifdef NETIF_F_TSO
+		/* Workaround for premature desc write-backs
+		 * in TSO mode.  Append 4-byte sentinel desc */
+		if (unlikely(mss && !nr_frags && size == len && size > 8))
+			size -= 4;
+#endif
 		buffer_info->length = size;
 		WARN_ON(buffer_info->dma != 0);
 		buffer_info->dma =
@@ -1324,6 +1333,13 @@ ixgb_tx_map(struct ixgb_adapter *adapter
 		while(len) {
 			buffer_info = &tx_ring->buffer_info[i];
 			size = min(len, IXGB_MAX_DATA_PER_TXD);
+#ifdef NETIF_F_TSO
+			/* Workaround for premature desc write-backs
+			 * in TSO mode.  Append 4-byte sentinel desc */
+			if (unlikely(mss && !nr_frags && size == len
+			             && size > 8))
+				size -= 4;
+#endif
 			buffer_info->length = size;
 			buffer_info->dma =
 				pci_map_page(adapter->pdev,
@@ -1401,8 +1417,9 @@ ixgb_tx_queue(struct ixgb_adapter *adapt
 /* Tx Descriptors needed, worst case */
 #define TXD_USE_COUNT(S) (((S) >> IXGB_MAX_TXD_PWR) + \
 			 (((S) & (IXGB_MAX_DATA_PER_TXD - 1)) ? 1 : 0))
-#define DESC_NEEDED TXD_USE_COUNT(IXGB_MAX_DATA_PER_TXD) + \
-	MAX_SKB_FRAGS * TXD_USE_COUNT(PAGE_SIZE) + 1
+#define DESC_NEEDED TXD_USE_COUNT(IXGB_MAX_DATA_PER_TXD) /* skb->date */ + \
+	MAX_SKB_FRAGS * TXD_USE_COUNT(PAGE_SIZE) + 1 /* for context */ \
+	+ 1 /* one more needed for sentinel TSO workaround */
 
 static int
 ixgb_xmit_frame(struct sk_buff *skb, struct net_device *netdev)



---
Auke Kok <auke-jan.h.kok@...el.com>
-
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