[3.8.y.z extended stable] Patch "bnx2x: fix DMA unmapping of TSO split BDs" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    bnx2x: fix DMA unmapping of TSO split BDs

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.18.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From f640a6ed9cda0b5d9c9f0e0a7128a1ebed7e8a78 Mon Sep 17 00:00:00 2001
From: Michal Schmidt <mschmidt at redhat.com>
Date: Thu, 9 Jan 2014 14:36:27 +0100
Subject: bnx2x: fix DMA unmapping of TSO split BDs

[ Upstream commit 95e92fd40c967c363ad66b2fd1ce4dcd68132e54 ]

bnx2x triggers warnings with CONFIG_DMA_API_DEBUG=y:

  WARNING: CPU: 0 PID: 2253 at lib/dma-debug.c:887 check_unmap+0xf8/0x920()
  bnx2x 0000:28:00.0: DMA-API: device driver frees DMA memory with
  different size [device address=0x00000000da2b389e] [map size=1490 bytes]
  [unmap size=66 bytes]

The reason is that bnx2x splits a TSO BD into two BDs (headers + data)
using one DMA mapping for both, but it uses only the length of the first
BD when unmapping.

This patch fixes the bug by unmapping the whole length of the two BDs.

Signed-off-by: Michal Schmidt <mschmidt at redhat.com>
Reviewed-by: Eric Dumazet <edumazet at google.com>
Acked-by: Dmitry Kravkov <dmitry at broadcom.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c
index 3a73bb9..269eefa 100644
--- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c
+++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c
@@ -126,6 +126,7 @@ static u16 bnx2x_free_tx_pkt(struct bnx2x *bp, struct bnx2x_fp_txdata *txdata,
 	struct sk_buff *skb = tx_buf->skb;
 	u16 bd_idx = TX_BD(tx_buf->first_bd), new_cons;
 	int nbd;
+	u16 split_bd_len = 0;

 	/* prefetch skb end pointer to speedup dev_kfree_skb() */
 	prefetch(&skb->end);
@@ -133,10 +134,7 @@ static u16 bnx2x_free_tx_pkt(struct bnx2x *bp, struct bnx2x_fp_txdata *txdata,
 	DP(NETIF_MSG_TX_DONE, "fp[%d]: pkt_idx %d  buff @(%p)->skb %p\n",
 	   txdata->txq_index, idx, tx_buf, skb);

-	/* unmap first bd */
 	tx_start_bd = &txdata->tx_desc_ring[bd_idx].start_bd;
-	dma_unmap_single(&bp->pdev->dev, BD_UNMAP_ADDR(tx_start_bd),
-			 BD_UNMAP_LEN(tx_start_bd), DMA_TO_DEVICE);


 	nbd = le16_to_cpu(tx_start_bd->nbd) - 1;
@@ -155,12 +153,19 @@ static u16 bnx2x_free_tx_pkt(struct bnx2x *bp, struct bnx2x_fp_txdata *txdata,
 	--nbd;
 	bd_idx = TX_BD(NEXT_TX_IDX(bd_idx));

-	/* ...and the TSO split header bd since they have no mapping */
+	/* TSO headers+data bds share a common mapping. See bnx2x_tx_split() */
 	if (tx_buf->flags & BNX2X_TSO_SPLIT_BD) {
+		tx_data_bd = &txdata->tx_desc_ring[bd_idx].reg_bd;
+		split_bd_len = BD_UNMAP_LEN(tx_data_bd);
 		--nbd;
 		bd_idx = TX_BD(NEXT_TX_IDX(bd_idx));
 	}

+	/* unmap first bd */
+	dma_unmap_single(&bp->pdev->dev, BD_UNMAP_ADDR(tx_start_bd),
+			 BD_UNMAP_LEN(tx_start_bd) + split_bd_len,
+			 DMA_TO_DEVICE);
+
 	/* now free frags */
 	while (nbd > 0) {

--
1.8.3.2