Re: [PATCH] [12/22] Remove GFP_DMAs/unchecked_isa_dma checks in scsi_scan.c

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

On Mon, 2008-02-25 at 00:35 +0100, Andi Kleen wrote:
> Should not be needed because the block layer bounces that all.
> 
> Signed-off-by: Andi Kleen <ak@suse.de>
> 
> ---
>  drivers/scsi/scsi_scan.c |    6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> Index: linux/drivers/scsi/scsi_scan.c
> ===================================================================
> --- linux.orig/drivers/scsi/scsi_scan.c
> +++ linux/drivers/scsi/scsi_scan.c
> @@ -1010,8 +1010,7 @@ static int scsi_probe_and_add_lun(struct
>  	if (!sdev)
>  		goto out;
>  
> -	result = kmalloc(result_len, GFP_ATOMIC |
> -			((shost->unchecked_isa_dma) ? __GFP_DMA : 0));
> +	result = kmalloc(result_len, GFP_ATOMIC);
>  	if (!result)
>  		goto out_free_sdev;
>  
> @@ -1328,8 +1327,7 @@ static int scsi_report_lun_scan(struct s
>  	 * prevent us from finding any LUNs on this target.
>  	 */
>  	length = (max_scsi_report_luns + 1) * sizeof(struct scsi_lun);
> -	lun_data = kmalloc(length, GFP_ATOMIC |
> -			   (sdev->host->unchecked_isa_dma ? __GFP_DMA : 0));
> +	lun_data = kmalloc(length, GFP_ATOMIC);
>  	if (!lun_data) {
>  		printk(ALLOC_FAILURE_MSG, __FUNCTION__);
>  		goto out;

Andi, this can't be right.

You're removing something that's actually useful.  I'm happy to
substitute this kmalloc for kmalloc_mask on the device dma mask which
will do the same thing and so junk unchecked_isa_dma() that way (and
actually fix us up for other weird mask devices), but just using
ZONE_NORMAL is wrong because we'll then bounce all the time for
something we knew a priori how to avoid.

James