Re: [PATCH v2 8/8] scsi/pmcraid: Use sgl_alloc_order() and sgl_free_order()

[Hannes Reinecke <hare@suse.de>]

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@wdc.com>
> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
> Cc: linux-scsi@vger.kernel.org
> Cc: Martin K. Petersen <martin.petersen@oracle.com>
> Cc: Anil Ravindranath <anil_ravindranath@pmc-sierra.com>
> ---
>  drivers/scsi/Kconfig   |  1 +
>  drivers/scsi/pmcraid.c | 43 ++++---------------------------------------
>  drivers/scsi/pmcraid.h |  2 +-
>  3 files changed, 6 insertions(+), 40 deletions(-)
> 
> diff --git a/drivers/scsi/Kconfig b/drivers/scsi/Kconfig
> index d11e75e76195..632200ec36a6 100644
> --- a/drivers/scsi/Kconfig
> +++ b/drivers/scsi/Kconfig
> @@ -1576,6 +1576,7 @@ config ZFCP
>  config SCSI_PMCRAID
>  	tristate "PMC SIERRA Linux MaxRAID adapter support"
>  	depends on PCI && SCSI && NET
> +	select SGL_ALLOC
>  	---help---
>  	  This driver supports the PMC SIERRA MaxRAID adapters.
>  
> diff --git a/drivers/scsi/pmcraid.c b/drivers/scsi/pmcraid.c
> index b4d6cd8cd1ad..95fc0352f9bb 100644
> --- a/drivers/scsi/pmcraid.c
> +++ b/drivers/scsi/pmcraid.c
> @@ -3232,12 +3232,7 @@ static int pmcraid_build_ioadl(
>   */
>  static void pmcraid_free_sglist(struct pmcraid_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);
>  }
>  
> @@ -3254,50 +3249,20 @@ static void pmcraid_free_sglist(struct pmcraid_sglist *sglist)
>  static struct pmcraid_sglist *pmcraid_alloc_sglist(int buflen)
>  {
>  	struct pmcraid_sglist *sglist;
> -	struct scatterlist *scatterlist;
> -	struct page *page;
> -	int num_elem, i, j;
>  	int sg_size;
>  	int order;
> -	int bsize_elem;
>  
>  	sg_size = buflen / (PMCRAID_MAX_IOADLS - 1);
>  	order = (sg_size > 0) ? get_order(sg_size) : 0;
> -	bsize_elem = PAGE_SIZE * (1 << order);
> -
> -	/* Determine the actual number of sg entries needed */
> -	if (buflen % bsize_elem)
> -		num_elem = (buflen / bsize_elem) + 1;
> -	else
> -		num_elem = buflen / bsize_elem;
>  
>  	/* Allocate a scatter/gather list for the DMA */
> -	sglist = kzalloc(sizeof(struct pmcraid_sglist) +
> -			 (sizeof(struct scatterlist) * (num_elem - 1)),
> -			 GFP_KERNEL);
> -
> +	sglist = kzalloc(sizeof(struct pmcraid_sglist), GFP_KERNEL);
>  	if (sglist == NULL)
>  		return NULL;
>  
> -	scatterlist = sglist->scatterlist;
> -	sg_init_table(scatterlist, num_elem);
>  	sglist->order = order;
> -	sglist->num_sg = num_elem;
> -	sg_size = buflen;
> -
> -	for (i = 0; i < num_elem; i++) {
> -		page = alloc_pages(GFP_KERNEL|GFP_DMA|__GFP_ZERO, order);
> -		if (!page) {
> -			for (j = i - 1; j >= 0; j--)
> -				__free_pages(sg_page(&scatterlist[j]), order);
> -			kfree(sglist);
> -			return NULL;
> -		}
> -
> -		sg_set_page(&scatterlist[i], page,
> -			sg_size < bsize_elem ? sg_size : bsize_elem, 0);
> -		sg_size -= bsize_elem;
> -	}
> +	sgl_alloc_order(buflen, order, false,
> +			GFP_KERNEL | GFP_DMA | __GFP_ZERO, &sglist->num_sg);
>  
>  	return sglist;
>  }
> diff --git a/drivers/scsi/pmcraid.h b/drivers/scsi/pmcraid.h
> index 44da91712115..754ef30927e2 100644
> --- a/drivers/scsi/pmcraid.h
> +++ b/drivers/scsi/pmcraid.h
> @@ -542,7 +542,7 @@ struct pmcraid_sglist {
>  	u32 order;
>  	u32 num_sg;
>  	u32 num_dma_sg;
> -	struct scatterlist scatterlist[1];
> +	struct scatterlist *scatterlist;
>  };
>  
>  /* page D0 inquiry data of focal point resource */
> 
The comment to ipr applied here, too.
We need input from the pmcraid folks if this is a valid conversion.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
hare@suse.de			               +49 911 74053 688
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