Re: PATCH: (as141b) Unaligned scatter-gather buffers and usb-storage

[James Bottomley <James.Bottomley@steeleye.com>]

On Mon, 2004-01-05 at 16:58, Alan Stern wrote:
> ===== st.c 1.45 vs edited =====
> --- 1.45/drivers/scsi/st.c	Fri Sep  5 12:16:40 2003
> +++ edited/drivers/scsi/st.c	Fri Nov 21 12:30:34 2003
> @@ -1267,7 +1267,8 @@
>  		i = STp->try_dio && try_rdio;
>  	else
>  		i = STp->try_dio && try_wdio;
> -	if (i) {
> +	if (i && ((unsigned int)buf & queue_dma_alignment(

This needs to be unsigned long, otherwise it will print a warning on a
64 bit compile.

> ===== scsi_lib.c 1.49 vs edited =====
> --- 1.49/drivers/scsi/scsi_lib.c	Sat Nov 22 11:20:45 2003
> +++ edited/drivers/scsi/scsi_lib.c	Mon Jan  5 16:55:32 2004
> @@ -1287,6 +1287,15 @@
>  	blk_queue_max_sectors(q, shost->max_sectors);
>  	blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
>  	blk_queue_segment_boundary(q, shost->dma_boundary);
> + 
> +	/*
> +	 * Set the queue's mask to require a mere 8-byte alignment for
> +	 * DMA buffers, rather than the default 512.  This shouldn't
> +	 * inconvenience any user programs and should be okay for most
> +	 * host adapters.  A host driver can alter this mask in its
> +	 * slave_alloc() or slave_configure() callback if necessary.
> +	 */
> +	blk_queue_dma_alignment(sdev->request_queue, (8 - 1));

sdev->request_queue is NULL here (it's filled in by the return from this
function.  The argument should be q.

I'll make the changes and apply the patch.

James