[ 3.5.y.z extended stable ] Patch "8139cp: Add dma_mapping_error checking" has been added to staging queue

[Luis Henriques]

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

    8139cp: Add dma_mapping_error checking

to the linux-3.5.y-queue branch of the 3.5.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-3.5.y-queue

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

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 3e7440a74378bbbdcb432529757e9ca9cf69b45e Mon Sep 17 00:00:00 2001
From: Neil Horman <nhorman at tuxdriver.com>
Date: Wed, 31 Jul 2013 09:03:56 -0400
Subject: [PATCH] 8139cp: Add dma_mapping_error checking

commit cf3c4c03060b688cbc389ebc5065ebcce5653e96 upstream.

Self explanitory dma_mapping_error addition to the 8139 driver, based on this:
https://bugzilla.redhat.com/show_bug.cgi?id=947250

It showed several backtraces arising for dma_map_* usage without checking the
return code on the mapping.  Add the check and abort the rx/tx operation if its
failed.  Untested as I have no hardware and the reporter has wandered off, but
seems pretty straightforward.

Signed-off-by: Neil Horman <nhorman at tuxdriver.com>
CC: "David S. Miller" <davem at davemloft.net>
CC: Francois Romieu <romieu at fr.zoreil.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/net/ethernet/realtek/8139cp.c | 48 ++++++++++++++++++++++++++++++++---
 1 file changed, 45 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/realtek/8139cp.c b/drivers/net/ethernet/realtek/8139cp.c
index d9ef667..bf8eb57 100644
--- a/drivers/net/ethernet/realtek/8139cp.c
+++ b/drivers/net/ethernet/realtek/8139cp.c
@@ -478,7 +478,7 @@ rx_status_loop:

 	while (1) {
 		u32 status, len;
-		dma_addr_t mapping;
+		dma_addr_t mapping, new_mapping;
 		struct sk_buff *skb, *new_skb;
 		struct cp_desc *desc;
 		const unsigned buflen = cp->rx_buf_sz;
@@ -520,6 +520,13 @@ rx_status_loop:
 			goto rx_next;
 		}

+		new_mapping = dma_map_single(&cp->pdev->dev, new_skb->data, buflen,
+					 PCI_DMA_FROMDEVICE);
+		if (dma_mapping_error(&cp->pdev->dev, new_mapping)) {
+			dev->stats.rx_dropped++;
+			goto rx_next;
+		}
+
 		dma_unmap_single(&cp->pdev->dev, mapping,
 				 buflen, PCI_DMA_FROMDEVICE);

@@ -531,12 +538,11 @@ rx_status_loop:

 		skb_put(skb, len);

-		mapping = dma_map_single(&cp->pdev->dev, new_skb->data, buflen,
-					 PCI_DMA_FROMDEVICE);
 		cp->rx_skb[rx_tail] = new_skb;

 		cp_rx_skb(cp, skb, desc);
 		rx++;
+		mapping = new_mapping;

 rx_next:
 		cp->rx_ring[rx_tail].opts2 = 0;
@@ -707,6 +713,22 @@ static inline u32 cp_tx_vlan_tag(struct sk_buff *skb)
 		TxVlanTag | swab16(vlan_tx_tag_get(skb)) : 0x00;
 }

+static void unwind_tx_frag_mapping(struct cp_private *cp, struct sk_buff *skb,
+				   int first, int entry_last)
+{
+	int frag, index;
+	struct cp_desc *txd;
+	skb_frag_t *this_frag;
+	for (frag = 0; frag+first < entry_last; frag++) {
+		index = first+frag;
+		cp->tx_skb[index] = NULL;
+		txd = &cp->tx_ring[index];
+		this_frag = &skb_shinfo(skb)->frags[frag];
+		dma_unmap_single(&cp->pdev->dev, le64_to_cpu(txd->addr),
+				 skb_frag_size(this_frag), PCI_DMA_TODEVICE);
+	}
+}
+
 static netdev_tx_t cp_start_xmit (struct sk_buff *skb,
 					struct net_device *dev)
 {
@@ -740,6 +762,9 @@ static netdev_tx_t cp_start_xmit (struct sk_buff *skb,

 		len = skb->len;
 		mapping = dma_map_single(&cp->pdev->dev, skb->data, len, PCI_DMA_TODEVICE);
+		if (dma_mapping_error(&cp->pdev->dev, mapping))
+			goto out_dma_error;
+
 		txd->opts2 = opts2;
 		txd->addr = cpu_to_le64(mapping);
 		wmb();
@@ -777,6 +802,9 @@ static netdev_tx_t cp_start_xmit (struct sk_buff *skb,
 		first_len = skb_headlen(skb);
 		first_mapping = dma_map_single(&cp->pdev->dev, skb->data,
 					       first_len, PCI_DMA_TODEVICE);
+		if (dma_mapping_error(&cp->pdev->dev, first_mapping))
+			goto out_dma_error;
+
 		cp->tx_skb[entry] = skb;
 		entry = NEXT_TX(entry);

@@ -790,6 +818,11 @@ static netdev_tx_t cp_start_xmit (struct sk_buff *skb,
 			mapping = dma_map_single(&cp->pdev->dev,
 						 skb_frag_address(this_frag),
 						 len, PCI_DMA_TODEVICE);
+			if (dma_mapping_error(&cp->pdev->dev, mapping)) {
+				unwind_tx_frag_mapping(cp, skb, first_entry, entry);
+				goto out_dma_error;
+			}
+
 			eor = (entry == (CP_TX_RING_SIZE - 1)) ? RingEnd : 0;

 			ctrl = eor | len | DescOwn;
@@ -848,11 +881,16 @@ static netdev_tx_t cp_start_xmit (struct sk_buff *skb,
 	if (TX_BUFFS_AVAIL(cp) <= (MAX_SKB_FRAGS + 1))
 		netif_stop_queue(dev);

+out_unlock:
 	spin_unlock_irqrestore(&cp->lock, intr_flags);

 	cpw8(TxPoll, NormalTxPoll);

 	return NETDEV_TX_OK;
+out_dma_error:
+	kfree_skb(skb);
+	cp->dev->stats.tx_dropped++;
+	goto out_unlock;
 }

 /* Set or clear the multicast filter for this adaptor.
@@ -1039,6 +1077,10 @@ static int cp_refill_rx(struct cp_private *cp)

 		mapping = dma_map_single(&cp->pdev->dev, skb->data,
 					 cp->rx_buf_sz, PCI_DMA_FROMDEVICE);
+		if (dma_mapping_error(&cp->pdev->dev, mapping)) {
+			kfree_skb(skb);
+			goto err_out;
+		}
 		cp->rx_skb[i] = skb;

 		cp->rx_ring[i].opts2 = 0;
--
1.8.3.2