Re: [PATCH] e100: Do pci_dma_sync after skb_alloc for proper operationon ixp4xx

From: David Acker
Date: Sat Jun 21 2008 - 21:57:44 EST


Kevin Hao wrote:
Hi,

The E100 device can't work on current kernel (2.6.26-rc6) and will cause
kernel corruption on intel ixdp4xx. This patch fix this regression.

Hello, this is pretty much the same patch that Anders Grafström sent on 6/18. I think it looks good; I am sorry I missed this. I think this can be ok'ed if folks can test it on a few different ARM platforms and of course x86.

I am getting sinus surgery this Monday but I should be back in the office within a week. I will give it a try then. I will test it on an ixp425 board and an PXA255 board. Just so you know, I found the in-kernel packet generator to be a good test. I also found using the board as a router between wired and wireless devices to catch issues that led me to posting patches for this driver in the first place.

-ack

---
commit c1f24812b9de182a4272724a2e84ea1ae5dd4659
Author: Kevin Hao <kexin.hao@xxxxxxxxxxxxx>
Date: Sat Jun 21 16:50:50 2008 +0800

e100: Do pci_dma_sync after skb_alloc for proper operation on ixp4xx
Do a DMA sync after we've allocated a new skb and link it with the previous
RFD. Otherwise the previous RFD may reference the previously freed skb
and cause kernel corruption.
Previously there was such a DMA sync at this place, but it was removed
by commit 7734f6e6bcd7ba78b00e93e74a4ddafd9886cdea.
Restoring this sync operation eliminates the regression.
Signed-off-by: Kevin Hao <kexin.hao@xxxxxxxxxxxxx>

diff --git a/drivers/net/e100.c b/drivers/net/e100.c
index f3cba5e..1037b13 100644
--- a/drivers/net/e100.c
+++ b/drivers/net/e100.c
@@ -1803,6 +1803,8 @@ static int e100_rx_alloc_skb(struct nic *nic, struct rx *rx)
if (rx->prev->skb) {
struct rfd *prev_rfd = (struct rfd *)rx->prev->skb->data;
put_unaligned_le32(rx->dma_addr, &prev_rfd->link);
+ pci_dma_sync_single_for_device(nic->pdev, rx->prev->dma_addr,
+ sizeof(struct rfd), PCI_DMA_TODEVICE);
}
return 0;
---

Best Regards,
Kevin


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