Re: [PATCH] sky2: Fix WARNING: at lib/dma-debug.c:902 check_sync

[Michael Breuer]

On 1/21/2010 3:41 PM, Jarek Poplawski wrote:
> On Thu, Jan 21, 2010 at 02:59:19PM -0500, Michael Breuer wrote:
>    
> > On 1/20/2010 4:41 AM, Jarek Poplawski wrote:
> >      
> > > [ previously: Re: [PATCH] af_packet: Don't use skb after dev_queue_xmit() ]
> > > diff --git a/drivers/net/sky2.c b/drivers/net/sky2.c
> > > index 7650f73..cdebdd3 100644
> > > --- a/drivers/net/sky2.c
> > > +++ b/drivers/net/sky2.c
> > > @@ -2252,12 +2252,14 @@ static struct sk_buff *receive_copy(struct sky2_port *sky2,
> > >   	skb = netdev_alloc_skb_ip_align(sky2->netdev, length);
> > >   	if (likely(skb)) {
> > >   		pci_dma_sync_single_for_cpu(sky2->hw->pdev, re->data_addr,
> > > -					    length, PCI_DMA_FROMDEVICE);
> > > +					    pci_unmap_len(re, data_size),
> > > +					    PCI_DMA_FROMDEVICE);
> > >   		skb_copy_from_linear_data(re->skb, skb->data, length);
> > >   		skb->ip_summed = re->skb->ip_summed;
> > >   		skb->csum = re->skb->csum;
> > >   		pci_dma_sync_single_for_device(sky2->hw->pdev, re->data_addr,
> > > -					       length, PCI_DMA_FROMDEVICE);
> > > +					       pci_unmap_len(re, data_size),
> > > +					       PCI_DMA_FROMDEVICE);
> > >   		re->skb->ip_summed = CHECKSUM_NONE;
> > >   		skb_put(skb, length);
> > >   	}
> > >        
> > Just a testing update: I went back to CONFIG_DMAR=Y yesterday and
> > have not (yet) encountered the sky2 crash I'd been having prior to
> > this fix. I've been pumping traffic through, and based on pre-patch
> > experience, it would likely have crashed by now.
> >
> > Will keep the system up for the next couple of days w/o reboot to
> > confirm that the sky2 lockup I'd been seeing has stopped happening
> > with this patch.
> >
> > Test notes:
> >
> > 1) Warning previously apparent on start (dma_debug check_sync) with
> > CONFIG_DMAR=n is gone.
> > 2) W/o the above patch, I was getting sky2 DMAR errors and
> > subsequent TX hangs requiring reboot to clear. The hangs happened
> > after at least 12 hours of uptime, and under RX load at the time of
> > the hang.
> > 3) With the above patch (and no other changes) I have not been able
> > to recreate the crash - the system is stable.
> >      
> Btw, could you remind us if during last dmar bugs jumbo frames might
> have been used or maybe mtu was changed, and the current test setting?
>
>    
I've hit this with and without Jumbo frames enabled. Last couple of 
recreations were with mtu = 1500, which is how I'm running now.
> > I have been following the discussion about the DMA api would suggest
> > that the length issue when DMAR is enabled is less innocuous than
> > previously believed.
> >      
> Actually, the last conclusions are - it's more innocuous than ever
> believed, and I completely agree with this (at least until the next
> week ;-).
>    
I stand grammatically corrected.
> Thanks,
> Jarek P.
>    

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