Re: [net PATCH] atl1c: Fix misuse of netdev_alloc_skb in refilling rx ring

Neil Horman
2013-07-26T17:02:51Z

On Fri, Jul 26, 2013 at 05:56:16PM +0100, Luis Henriques wrote:
> Neil Horman <nhorman@tuxdriver.com> writes:
>
> > atl1c uses netdev_alloc_skb to refill its rx dma ring, but that call makes no
> > guarantees about the suitability of the memory for use in DMA. As a result
> > we've gotten reports of atl1c drivers occasionally hanging and needing to be
> > reset:
> > https://bugzilla.kernel.org/show_bug.cgi?id=54021
> >
> > Fix this by modifying the call to use the internal version __netdev_alloc_skb,
> > where you can set the gfp_mask explicitly to include GFP_DMA.
> >
> > Tested by two reporters in the above bug, who have the hardware to validate it.
> > Both report immediate cessation of the problem with this patch
> >
> > Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
> > CC: Jay Cliburn <jcliburn@gmail.com>
> > CC: "David S. Miller" <davem@davemloft.net>
> > CC: stable@vger.kernel.org
> > Tested-by: Luis Henrix <luis.henrix@gmail.com>
>
> Thanks Neil!
>
> Would it be possible for you to update my name and email? (I've just
> updated my bz account to remove my gmail account address -- I thought
> I had done this ages ago.)
>
> Tested-by: Luis Henriques <luis.henriques@canonical.com>
>
I'm sure if Dave has time, he will square that up.
Neil

> Cheers,
> --
> Luis
>
>
> > Tested-by: Vincent Alquier <vincent.alquier@gmail.com> ---
> > drivers/net/ethernet/atheros/atl1c/atl1c_main.c | 2 +- 1 file
> > changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/ethernet/atheros/atl1c/atl1c_main.c b/drivers/net/ethernet/atheros/atl1c/atl1c_main.c
> > index 786a874..d5e38d1 100644
> > --- a/drivers/net/ethernet/atheros/atl1c/atl1c_main.c
> > +++ b/drivers/net/ethernet/atheros/atl1c/atl1c_main.c
> > @@ -1660,7 +1660,7 @@ static int atl1c_alloc_rx_buffer(struct atl1c_adapter *adapter)
> > while (next_info->flags & ATL1C_BUFFER_FREE) {
> > rfd_desc = ATL1C_RFD_DESC(rfd_ring, rfd_next_to_use);
> >
> > - skb = netdev_alloc_skb(adapter->netdev, adapter->rx_buffer_len);
> > + skb = __netdev_alloc_skb(adapter->netdev, adapter->rx_buffer_len, GFP_ATOMIC|GFP_DMA);
> > if (unlikely(!skb)) {
> > if (netif_msg_rx_err(adapter))
> > dev_warn(&pdev->dev, "alloc rx buffer failed\n");
>
>