[PATCH] null_blk: Use bitmap_zalloc() when applicable

[PATCH] null_blk: Use bitmap_zalloc() when applicable

[Christophe JAILLET]

'nq->tag_map' is a bitmap. So use bitmap_zalloc() to simplify code and
improve the semantic.

Also change the corresponding kfree() into bitmap_free() to keep
consistency.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
 drivers/block/null_blk/main.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index 6be6ccd4a28f..9e058e0aa668 100644
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -1661,7 +1661,7 @@ static blk_status_t null_queue_rq(struct blk_mq_hw_ctx *hctx,
 
 static void cleanup_queue(struct nullb_queue *nq)
 {
-	kfree(nq->tag_map);
+	bitmap_free(nq->tag_map);
 	kfree(nq->cmds);
 }
 
@@ -1790,14 +1790,13 @@ static const struct block_device_operations null_rq_ops = {
 static int setup_commands(struct nullb_queue *nq)
 {
 	struct nullb_cmd *cmd;
-	int i, tag_size;
+	int i;
 
 	nq->cmds = kcalloc(nq->queue_depth, sizeof(*cmd), GFP_KERNEL);
 	if (!nq->cmds)
 		return -ENOMEM;
 
-	tag_size = ALIGN(nq->queue_depth, BITS_PER_LONG) / BITS_PER_LONG;
-	nq->tag_map = kcalloc(tag_size, sizeof(unsigned long), GFP_KERNEL);
+	nq->tag_map = bitmap_zalloc(nq->queue_depth, GFP_KERNEL);
 	if (!nq->tag_map) {
 		kfree(nq->cmds);
 		return -ENOMEM;
-- 
2.32.0

Re: [PATCH] null_blk: Use bitmap_zalloc() when applicable

[Damien Le Moal]

On 12/24/21 06:55, Christophe JAILLET wrote:
> 'nq->tag_map' is a bitmap. So use bitmap_zalloc() to simplify code and
> improve the semantic.
> 
> Also change the corresponding kfree() into bitmap_free() to keep
> consistency.
> 
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> ---
>  drivers/block/null_blk/main.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
> index 6be6ccd4a28f..9e058e0aa668 100644
> --- a/drivers/block/null_blk/main.c
> +++ b/drivers/block/null_blk/main.c
> @@ -1661,7 +1661,7 @@ static blk_status_t null_queue_rq(struct blk_mq_hw_ctx *hctx,
>  
>  static void cleanup_queue(struct nullb_queue *nq)
>  {
> -	kfree(nq->tag_map);
> +	bitmap_free(nq->tag_map);
>  	kfree(nq->cmds);
>  }
>  
> @@ -1790,14 +1790,13 @@ static const struct block_device_operations null_rq_ops = {
>  static int setup_commands(struct nullb_queue *nq)
>  {
>  	struct nullb_cmd *cmd;
> -	int i, tag_size;
> +	int i;
>  
>  	nq->cmds = kcalloc(nq->queue_depth, sizeof(*cmd), GFP_KERNEL);
>  	if (!nq->cmds)
>  		return -ENOMEM;
>  
> -	tag_size = ALIGN(nq->queue_depth, BITS_PER_LONG) / BITS_PER_LONG;
> -	nq->tag_map = kcalloc(tag_size, sizeof(unsigned long), GFP_KERNEL);
> +	nq->tag_map = bitmap_zalloc(nq->queue_depth, GFP_KERNEL);
>  	if (!nq->tag_map) {
>  		kfree(nq->cmds);
>  		return -ENOMEM;

Before this patch, tag_size would always be a multiple of BITS_PER_LONG.
Using bitmap_zalloc(), that alignment goes away, but I think this is OK.

Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>

-- 
Damien Le Moal
Western Digital Research

Re: [PATCH] null_blk: Use bitmap_zalloc() when applicable

[Dan Carpenter]

On Thu, Dec 30, 2021 at 11:28:28AM +0900, Damien Le Moal wrote:
> >  
> > -	tag_size = ALIGN(nq->queue_depth, BITS_PER_LONG) / BITS_PER_LONG;
> > -	nq->tag_map = kcalloc(tag_size, sizeof(unsigned long), GFP_KERNEL);
> > +	nq->tag_map = bitmap_zalloc(nq->queue_depth, GFP_KERNEL);
> >  	if (!nq->tag_map) {
> >  		kfree(nq->cmds);
> >  		return -ENOMEM;
> 
> Before this patch, tag_size would always be a multiple of BITS_PER_LONG.
> Using bitmap_zalloc(), that alignment goes away, but I think this is OK.
> 

It's still going to be a multiple of long.  Bitmaps are always stored
in longs.

regards,
dan carpenter

Re: [PATCH] null_blk: Use bitmap_zalloc() when applicable

[Damien Le Moal]

On 1/6/22 16:44, Dan Carpenter wrote:
> On Thu, Dec 30, 2021 at 11:28:28AM +0900, Damien Le Moal wrote:
>>>  
>>> -	tag_size = ALIGN(nq->queue_depth, BITS_PER_LONG) / BITS_PER_LONG;
>>> -	nq->tag_map = kcalloc(tag_size, sizeof(unsigned long), GFP_KERNEL);
>>> +	nq->tag_map = bitmap_zalloc(nq->queue_depth, GFP_KERNEL);
>>>  	if (!nq->tag_map) {
>>>  		kfree(nq->cmds);
>>>  		return -ENOMEM;
>>
>> Before this patch, tag_size would always be a multiple of BITS_PER_LONG.
>> Using bitmap_zalloc(), that alignment goes away, but I think this is OK.
>>
> 
> It's still going to be a multiple of long.  Bitmaps are always stored
> in longs.

Yes, I understand that. I was referring to tag_size, which was rounded
before. But tag_size is only a local variable and not the actual queue
depth, which is not rounded. I got confused :)

> 
> regards,
> dan carpenter
> 


-- 
Damien Le Moal
Western Digital Research