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SubjectRe: [PATCH] e100: Do pci_dma_sync after skb_alloc for proper operation on ixp4xx
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@windriver.com>
> 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@windriver.com>
>
> 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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