linux-kernel - Re: [Outreachy kernel] [PATCH 2/7] staging: most: Using macro DIV_ROUND

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Date:   Tue, 21 Feb 2017 20:58:51 +0100 (CET)
From:   Julia Lawall <julia.lawall@...6.fr>
To:     simran singhal <singhalsimran0@...il.com>
cc:     gregkh@...uxfoundation.org, devel@...verdev.osuosl.org,
        linux-kernel@...r.kernel.org, outreachy-kernel@...glegroups.com
Subject: Re: [Outreachy kernel] [PATCH 2/7] staging: most: Using macro
 DIV_ROUND_UP



On Wed, 22 Feb 2017, simran singhal wrote:

> The macro DIV_ROUND_UP performs the computation (((n) + (d) - 1) /(d)).
> It clarifies the divisor calculations. This occurence was detected using
> the coccinelle script:
>
> @@
> expression e1;
> expression e2;
> @@
> (
> - ((e1) + e2 - 1) / (e2)
> + DIV_ROUND_UP(e1,e2)
> |
> - ((e1) + (e2 - 1)) / (e2)
> + DIV_ROUND_UP(e1,e2)
> )


DIV_ROUND_UP is defined in kernel.h, which defines some other generally
useful things.  Maybe there is an opportunity for making rules from some
of them also.

julia

>
> Signed-off-by: simran singhal <singhalsimran0@...il.com>
> ---
>  drivers/staging/most/hdm-dim2/dim2_hal.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/staging/most/hdm-dim2/dim2_hal.c b/drivers/staging/most/hdm-dim2/dim2_hal.c
> index 0b9816c..6824826 100644
> --- a/drivers/staging/most/hdm-dim2/dim2_hal.c
> +++ b/drivers/staging/most/hdm-dim2/dim2_hal.c
> @@ -49,7 +49,7 @@
>  #define DBR_SIZE  (16 * 1024) /* specified by IP */
>  #define DBR_BLOCK_SIZE  (DBR_SIZE / 32 / DBR_MAP_SIZE)
>
> -#define ROUND_UP_TO(x, d)  (((x) + (d) - 1) / (d) * (d))
> +#define ROUND_UP_TO(x, d)  (DIV_ROUND_UP(x, (d)) * (d))
>
>  /* -------------------------------------------------------------------------- */
>  /* generic helper functions and macros */
> @@ -117,7 +117,7 @@ static int alloc_dbr(u16 size)
>  		return DBR_SIZE; /* out of memory */
>
>  	for (i = 0; i < DBR_MAP_SIZE; i++) {
> -		u32 const blocks = (size + DBR_BLOCK_SIZE - 1) / DBR_BLOCK_SIZE;
> +		u32 const blocks = DIV_ROUND_UP(size, DBR_BLOCK_SIZE);
>  		u32 mask = ~((~(u32)0) << blocks);
>
>  		do {
> @@ -137,7 +137,7 @@ static int alloc_dbr(u16 size)
>  static void free_dbr(int offs, int size)
>  {
>  	int block_idx = offs / DBR_BLOCK_SIZE;
> -	u32 const blocks = (size + DBR_BLOCK_SIZE - 1) / DBR_BLOCK_SIZE;
> +	u32 const blocks = DIV_ROUND_UP(size, DBR_BLOCK_SIZE);
>  	u32 mask = ~((~(u32)0) << blocks);
>
>  	mask <<= block_idx % 32;
> --
> 2.7.4
>
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