[PATCH v2 6/8] scsi/ipr: Use sgl_alloc_order() and sgl_free_order()

[Hannes Reinecke]

On 10/17/2017 12:49 AM, Bart Van Assche wrote:
> Use the sgl_alloc_order() and sgl_free_order() functions instead
> of open coding these functions.
> 
> Signed-off-by: Bart Van Assche <bart.vanassche at wdc.com>
> Reviewed-by: Johannes Thumshirn <jthumshirn at suse.de>
> Cc: linux-scsi at vger.kernel.org
> Cc: Martin K. Petersen <martin.petersen at oracle.com>
> Cc: Brian King <brking at linux.vnet.ibm.com>
> ---
>  drivers/scsi/Kconfig |  1 +
>  drivers/scsi/ipr.c   | 49 ++++++++-----------------------------------------
>  drivers/scsi/ipr.h   |  2 +-
>  3 files changed, 10 insertions(+), 42 deletions(-)
> 
> diff --git a/drivers/scsi/Kconfig b/drivers/scsi/Kconfig
> index 41366339b950..d11e75e76195 100644
> --- a/drivers/scsi/Kconfig
> +++ b/drivers/scsi/Kconfig
> @@ -1058,6 +1058,7 @@ config SCSI_IPR
>  	depends on PCI && SCSI && ATA
>  	select FW_LOADER
>  	select IRQ_POLL
> +	select SGL_ALLOC
>  	---help---
>  	  This driver supports the IBM Power Linux family RAID adapters.
>  	  This includes IBM pSeries 5712, 5703, 5709, and 570A, as well
> diff --git a/drivers/scsi/ipr.c b/drivers/scsi/ipr.c
> index f838bd73befa..6fed5db6255e 100644
> --- a/drivers/scsi/ipr.c
> +++ b/drivers/scsi/ipr.c
> @@ -3815,10 +3815,8 @@ static struct device_attribute ipr_iopoll_weight_attr = {
>   **/
>  static struct ipr_sglist *ipr_alloc_ucode_buffer(int buf_len)
>  {
> -	int sg_size, order, bsize_elem, num_elem, i, j;
> +	int sg_size, order;
>  	struct ipr_sglist *sglist;
> -	struct scatterlist *scatterlist;
> -	struct page *page;
>  
>  	/* Get the minimum size per scatter/gather element */
>  	sg_size = buf_len / (IPR_MAX_SGLIST - 1);
> @@ -3826,45 +3824,18 @@ static struct ipr_sglist *ipr_alloc_ucode_buffer(int buf_len)
>  	/* Get the actual size per element */
>  	order = get_order(sg_size);
>  
> -	/* Determine the actual number of bytes per element */
> -	bsize_elem = PAGE_SIZE * (1 << order);
> -
> -	/* Determine the actual number of sg entries needed */
> -	if (buf_len % bsize_elem)
> -		num_elem = (buf_len / bsize_elem) + 1;
> -	else
> -		num_elem = buf_len / bsize_elem;
> -
>  	/* Allocate a scatter/gather list for the DMA */
> -	sglist = kzalloc(sizeof(struct ipr_sglist) +
> -			 (sizeof(struct scatterlist) * (num_elem - 1)),
> -			 GFP_KERNEL);
> -
> +	sglist = kzalloc(sizeof(struct ipr_sglist), GFP_KERNEL);
>  	if (sglist == NULL) {
>  		ipr_trace;
>  		return NULL;
>  	}
> -
> -	scatterlist = sglist->scatterlist;
> -	sg_init_table(scatterlist, num_elem);
> -
>  	sglist->order = order;
> -	sglist->num_sg = num_elem;
> -
> -	/* Allocate a bunch of sg elements */
> -	for (i = 0; i < num_elem; i++) {
> -		page = alloc_pages(GFP_KERNEL, order);
> -		if (!page) {
> -			ipr_trace;
> -
> -			/* Free up what we already allocated */
> -			for (j = i - 1; j >= 0; j--)
> -				__free_pages(sg_page(&scatterlist[j]), order);
> -			kfree(sglist);
> -			return NULL;
> -		}
> -
> -		sg_set_page(&scatterlist[i], page, 0, 0);
> +	sglist->scatterlist = sgl_alloc_order(buf_len, order, false, GFP_KERNEL,
> +					      &sglist->num_sg);
> +	if (!sglist->scatterlist) {
> +		kfree(sglist);
> +		return NULL;
>  	}
>  
>  	return sglist;
> @@ -3882,11 +3853,7 @@ static struct ipr_sglist *ipr_alloc_ucode_buffer(int buf_len)
>   **/
>  static void ipr_free_ucode_buffer(struct ipr_sglist *sglist)
>  {
> -	int i;
> -
> -	for (i = 0; i < sglist->num_sg; i++)
> -		__free_pages(sg_page(&sglist->scatterlist[i]), sglist->order);
> -
> +	sgl_free_order(sglist->scatterlist, sglist->order);
>  	kfree(sglist);
>  }
>  
> diff --git a/drivers/scsi/ipr.h b/drivers/scsi/ipr.h
> index c7f0e9e3cd7d..93570734cbfb 100644
> --- a/drivers/scsi/ipr.h
> +++ b/drivers/scsi/ipr.h
> @@ -1454,7 +1454,7 @@ struct ipr_sglist {
>  	u32 num_sg;
>  	u32 num_dma_sg;
>  	u32 buffer_len;
> -	struct scatterlist scatterlist[1];
> +	struct scatterlist *scatterlist;
>  };
>  
>  enum ipr_sdt_state {
> 
Not sure if this is a valid conversion.
Originally the driver would allocate a single buffer; with this buffer
we have two distinct buffers.
Given that this is used to download the microcode I'm not sure if this
isn't a hardware-dependent structure which requires a single buffer
including the sglist.
Brian, can you shed some light here?

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
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