Bug#506835: BUG: bad: [58e2a02eb18393e76a469580fedf7caec190eb5e] [SCSI] eata: convert to use the data buffer accessors

[Arthur Marsh <arthur.marsh@internode.on.net>]

I had a look at the current Debian 2.6.27 source and applied your patch 
manually against it.

It will take me a few hours to compile the new kernel and I should be 
able to test it in about 7 hours time.

Thanks again,

Arthur.

FUJITA Tomonori wrote, on 2008-12-22 12:39:
> On Mon, 22 Dec 2008 02:38:16 +1030
> Arthur Marsh <arthur.marsh@internode.on.net> wrote:
>
> > I've recently installed Debian on a PII-266 machine with DPT2044W SCSI 
> > controller.
> >
> > Kernels 2.6.18-2.6.22 work fine, and kernels 2.6.23-2.6.27 lock up after 
> > loading the eata module using modprobe, with the error:
> >
> > modprobe exited with preempt_count 1
> >
> > I've run a git bisection and have a few more passes to go, but suspect 
> > the commit in the subject line,
> >
> > [58e2a02eb18393e76a469580fedf7caec190eb5e] [SCSI] eata: convert to use 
> > the data buffer accessors
> >
> > to be the patch which triggers the problem.
> >
> > I'm not a C programmer, let alone a kernel programmer, but can build and 
> > check any suggested patches.
> >
> > Is anyone successfully using the eata module since the data buffer 
> > accessors patch?
> >
> > Is anyone able to examine the code to see if anything was done wrong in 
> > the data buffer accessors patch?
>
> Sorry about the problem. Can you try this patch?
>
>
> diff --git a/drivers/scsi/eata.c b/drivers/scsi/eata.c
> index a73a6bb..976cdd5 100644
> --- a/drivers/scsi/eata.c
> +++ b/drivers/scsi/eata.c
> @@ -1626,8 +1626,15 @@ static void map_dma(unsigned int i, struct hostdata *ha)
>  
>  	cpp->sense_len = SCSI_SENSE_BUFFERSIZE;
>  
> -	count = scsi_dma_map(SCpnt);
> -	BUG_ON(count < 0);
> +	if (!scsi_sg_count(SCpnt)) {
> +		cpp->data_len = 0;
> +		return;
> +	}
> +
> +	count = pci_map_sg(ha->pdev, scsi_sglist(SCpnt), scsi_sg_count(SCpnt),
> +			   pci_dir);
> +	BUG_ON(!count);
> +
>  	scsi_for_each_sg(SCpnt, sg, count, k) {
>  		cpp->sglist[k].address = H2DEV(sg_dma_address(sg));
>  		cpp->sglist[k].num_bytes = H2DEV(sg_dma_len(sg));
> @@ -1655,7 +1662,9 @@ static void unmap_dma(unsigned int i, struct hostdata *ha)
>  		pci_unmap_single(ha->pdev, DEV2H(cpp->sense_addr),
>  				 DEV2H(cpp->sense_len), PCI_DMA_FROMDEVICE);
>  
> -	scsi_dma_unmap(SCpnt);
> +	if (scsi_sg_count(SCpnt))
> +		pci_unmap_sg(ha->pdev, scsi_sglist(SCpnt), scsi_sg_count(SCpnt),
> +			     pci_dir);
>  
>  	if (!DEV2H(cpp->data_len))
>  		pci_dir = PCI_DMA_BIDIRECTIONAL;