Re: [PATCH] scsi: pmcraid: Use dma_pool_zalloc rather than dma_pool_alloc

[Joe Perches]

On Thu, 2019-07-18 at 20:10 +0200, Vasyl Gomonovych wrote:
> Use *_pool_zalloc rather than *_pool_alloc followed by memset with 0
> The semantic patch that makes this change is available
> in scripts/coccinelle/api/alloc/pool_zalloc-simple.cocci.
[]
> diff --git a/drivers/scsi/pmcraid.c b/drivers/scsi/pmcraid.c
[]
> @@ -4653,9 +4653,7 @@ static int pmcraid_allocate_control_blocks(struct 
> pmcraid_instance *pinstance)
>               return -ENOMEM;
>  
>       for (i = 0; i < PMCRAID_MAX_CMD; i++) {
> -             pinstance->cmd_list[i]->ioa_cb =
> -                     dma_pool_alloc(
> -                             pinstance->control_pool,
> +             pinstance->cmd_list[i]->ioa_cb = 
> dma_pool_zalloc(pinstance->control_pool,
>                               GFP_KERNEL,
>                               &(pinstance->cmd_list[i]->ioa_cb_bus_addr));
>  
> @@ -4663,8 +4661,6 @@ static int pmcraid_allocate_control_blocks(struct 
> pmcraid_instance *pinstance)
>                       pmcraid_release_control_blocks(pinstance, i);
>                       return -ENOMEM;
>               }
> -             memset(pinstance->cmd_list[i]->ioa_cb, 0,
> -                     sizeof(struct pmcraid_control_block));
>       }
>       return 0;
>  }

While this change is somewhat overdone as only
dma_pool_alloc could be changed to dma_pool_zalloc
on the same line without rewrapping other arguments,
I'd generally write this with a temporary like:
---
 drivers/scsi/pmcraid.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/drivers/scsi/pmcraid.c b/drivers/scsi/pmcraid.c
index 71ff3936da4f..88e7b18ad44d 100644
--- a/drivers/scsi/pmcraid.c
+++ b/drivers/scsi/pmcraid.c
@@ -4653,19 +4653,17 @@ static int pmcraid_allocate_control_blocks(struct 
pmcraid_instance *pinstance)
                return -ENOMEM;
 
        for (i = 0; i < PMCRAID_MAX_CMD; i++) {
-               pinstance->cmd_list[i]->ioa_cb =
-                       dma_pool_alloc(
-                               pinstance->control_pool,
-                               GFP_KERNEL,
-                               &(pinstance->cmd_list[i]->ioa_cb_bus_addr));
+               struct pmcraid_cmd *cmd = pinstance->cmd_list[i];
 
-               if (!pinstance->cmd_list[i]->ioa_cb) {
+               cmd->ioa_cb = dma_pool_zalloc(pinstance->control_pool,
+                                             GFP_KERNEL,
+                                             &cmd->ioa_cb_bus_addr);
+               if (!cmd->ioa_cb) {
                        pmcraid_release_control_blocks(pinstance, i);
                        return -ENOMEM;
                }
-               memset(pinstance->cmd_list[i]->ioa_cb, 0,
-                       sizeof(struct pmcraid_control_block));
        }
+
        return 0;
 }