[PATCH net-2.6] jme: Fix unmap error (Causing system freeze)

[PATCH net-2.6] jme: Fix unmap error (Causing system freeze)

[cooldavid]

From: Guo-Fu Tseng <cooldavid@cooldavid.org>


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@kernel.org
Signed-off-by: Guo-Fu Tseng <cooldavid@cooldavid.org>
---
 drivers/net/jme.c |   20 ++++++++++++++------
 1 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/drivers/net/jme.c b/drivers/net/jme.c
index b5b174a..1973814 100644
--- a/drivers/net/jme.c
+++ b/drivers/net/jme.c
@@ -753,20 +753,28 @@ 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;
 }
 
-- 
1.7.3.4

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Re: [PATCH net-2.6] jme: Fix unmap error (Causing system freeze)

[Chris Wright]

* cooldavid@cooldavid.org (cooldavid@cooldavid.org) wrote:
> From: Guo-Fu Tseng <cooldavid@cooldavid.org>
> 
> 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. :)

Also referred to in kernel bugzilla:

https://bugzilla.kernel.org/show_bug.cgi?id=39312

> Cc: stable@kernel.org
> Signed-off-by: Guo-Fu Tseng <cooldavid@cooldavid.org>

Acked-by: Chris Wright <chrisw@sous-sol.org>

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Re: [PATCH net-2.6] jme: Fix unmap error (Causing system freeze)

[David Miller]

From: Chris Wright <chrisw@sous-sol.org>
Date: Thu, 21 Jul 2011 12:30:08 -0700

> * cooldavid@cooldavid.org (cooldavid@cooldavid.org) wrote:
>> From: Guo-Fu Tseng <cooldavid@cooldavid.org>
>> 
>> 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. :)
> 
> Also referred to in kernel bugzilla:
> 
> https://bugzilla.kernel.org/show_bug.cgi?id=39312
> 
>> Cc: stable@kernel.org
>> Signed-off-by: Guo-Fu Tseng <cooldavid@cooldavid.org>
> 
> Acked-by: Chris Wright <chrisw@sous-sol.org>

Applied, but it's too late for 3.0 so I'll just submit it to all
the -stable branches after 3.0-final is released.

Thanks.

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Re: [PATCH net-2.6] jme: Fix unmap error (Causing system freeze)

[Michał Mirosław]

2011/7/21  <cooldavid@cooldavid.org>:
> From: Guo-Fu Tseng <cooldavid@cooldavid.org>
>
> 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.

My patch also fixed another issue - from correctness point of view,
you should not use virt_to_page+dma_map_page here, but dma_map_single.

Best Regards,
Michał Mirosław

Re: [PATCH net-2.6] jme: Fix unmap error (Causing system freeze)

[Guo-Fu Tseng]

On Fri, 22 Jul 2011 09:45:42 +0200, Michał Mirosław wrote
> 2011/7/21  <cooldavid@cooldavid.org>:
> > From: Guo-Fu Tseng <cooldavid@cooldavid.org>
> >
> > 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.
> 
> My patch also fixed another issue - from correctness point of view,
> you should not use virt_to_page+dma_map_page here, but dma_map_single.
> 
> Best Regards,
> Michał Mirosław
Hi Michał:

Yes, I did noticed that. :)

And I agreed that using {dma|pci}_map_single is better than
calling virt_to_page in driver.

It's just that I'm not sure if it is really preferred to use
dma_map_single over pci_map_single for PCI device driver?

You are very welcome to send another patch for converting the
DMA API using.

Guo-Fu Tseng

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