linux-kernel - Re: [PATCH] bcache: replace snprintf in show functions with sysfs

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Date:   Wed, 13 Oct 2021 14:59:09 +0800
From:   Coly Li <colyli@...e.de>
To:     Qing Wang <wangqing@...o.com>
Cc:     Kent Overstreet <kent.overstreet@...il.com>,
        linux-bcache@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] bcache: replace snprintf in show functions with
 sysfs_emit

On 10/13/21 11:27 AM, Qing Wang wrote:
> coccicheck complains about the use of snprintf() in sysfs show functions.
>
> Fix the coccicheck warning:
> WARNING: use scnprintf or sprintf.
>
> Use sysfs_emit instead of scnprintf or sprintf makes more sense.
>
> Signed-off-by: Qing Wang <wangqing@...o.com>
> ---
>   drivers/md/bcache/sysfs.c | 2 +-
>   drivers/md/bcache/sysfs.h | 2 +-
>   2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
> index 05ac1d6..e146c9e 100644
> --- a/drivers/md/bcache/sysfs.c
> +++ b/drivers/md/bcache/sysfs.c
> @@ -639,7 +639,7 @@ static int bch_bset_print_stats(struct cache_set *c, char *buf)
>   	if (ret < 0)
>   		return ret;
>   
> -	return snprintf(buf, PAGE_SIZE,
> +	return sysfs_emit(buf,
>   			"btree nodes:		%zu\n"
>   			"written sets:		%zu\n"
>   			"unwritten sets:		%zu\n"

Let's keep this location as snprintf(), to make code style be consistent.


> diff --git a/drivers/md/bcache/sysfs.h b/drivers/md/bcache/sysfs.h
> index 215df32..8bec32d 100644
> --- a/drivers/md/bcache/sysfs.h
> +++ b/drivers/md/bcache/sysfs.h
> @@ -51,7 +51,7 @@ STORE(fn)								\
>   #define sysfs_printf(file, fmt, ...)					\
>   do {									\
>   	if (attr == &sysfs_ ## file)					\
> -		return snprintf(buf, PAGE_SIZE, fmt "\n", __VA_ARGS__);	\
> +		return sysfs_emit(buf, fmt "\n", __VA_ARGS__);	\
>   } while (0)
>   
>   #define sysfs_print(file, var)						\

IMHO I like this change :-) BTW, for snprint() from util.h, it seems 
only to be used by sysfs_print() in syfs.h, would you like to change it 
to use sysfs_emit too ?

Thanks for the patch.

Coly Li