From: Guo-Fu Tseng <cooldavid@cooldavid.org>
Date: Thu, 21 Jul 2011 02:21:05 +0000 (+0800)
Subject: jme: Fix unmap error (Causing system freeze)
X-Git-Url: http://bbs.cooldavid.org/git/?p=jme.git;a=commitdiff_plain;h=52edb99adf51118bb19943a38063d2554761fc68

jme: Fix unmap error (Causing system freeze)

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. :)
---

diff --git a/jme.c b/jme.c
index 6b2a5e7..140aef9 100644
--- a/jme.c
+++ b/jme.c
@@ -751,20 +751,28 @@ jme_make_new_rx_buf(struct jme_adapter *jme, int i)
 	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;
 }