[PATCH] [6/50] jme: Fix unmap error (Causing system freeze)

[Andi Kleen]

2.6.35-longterm review patch.  If anyone has any objections, please let me know.

------------------
From: Guo-Fu Tseng <cooldavid@xxxxxxxxxxxxx>

[ upstream commit 94c5b41b327e08de0ddf563237855f55080652a1 ]

This patch add the missing dma_unmap().
Which solved the critical issue of system freeze on heavy load.

Michal Miroslaw's rejected patch:
[PATCH v2 10/46] net: jme: convert to generic DMA API
Pointed out the issue also, thank you Michal.
But the fix was incorrect. It would unmap needed address
when low memory.

Got lots of feedback from End user and Gentoo Bugzilla.
https://bugs.gentoo.org/show_bug.cgi?id=373109
Thank you all. :)

Cc: stable@xxxxxxxxxx
Signed-off-by: Guo-Fu Tseng <cooldavid@xxxxxxxxxxxxx>
Acked-by: Chris Wright <chrisw@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>

Index: linux-2.6.35.y/drivers/net/jme.c
===================================================================
--- linux-2.6.35.y.orig/drivers/net/jme.c
+++ linux-2.6.35.y/drivers/net/jme.c
@@ -678,20 +678,28 @@ jme_make_new_rx_buf(struct jme_adapter *
 	struct jme_ring *rxring = &(jme->rxring[0]);
 	struct jme_buffer_info *rxbi = rxring->bufinf + i;
 	struct sk_buff *skb;
+	dma_addr_t mapping;
 
 	skb = netdev_alloc_skb(jme->dev,
 		jme->dev->mtu + RX_EXTRA_LEN);
 	if (unlikely(!skb))
 		return -ENOMEM;
 
+	mapping = pci_map_page(jme->pdev, virt_to_page(skb->data),
+			       offset_in_page(skb->data), skb_tailroom(skb),
+			       PCI_DMA_FROMDEVICE);
+	if (unlikely(pci_dma_mapping_error(jme->pdev, mapping))) {
+		dev_kfree_skb(skb);
+		return -ENOMEM;
+	}
+
+	if (likely(rxbi->mapping))
+		pci_unmap_page(jme->pdev, rxbi->mapping,
+			       rxbi->len, PCI_DMA_FROMDEVICE);
+
 	rxbi->skb = skb;
 	rxbi->len = skb_tailroom(skb);
-	rxbi->mapping = pci_map_page(jme->pdev,
-					virt_to_page(skb->data),
-					offset_in_page(skb->data),
-					rxbi->len,
-					PCI_DMA_FROMDEVICE);
-
+	rxbi->mapping = mapping;
 	return 0;
 }
 
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