linux-kernel - Re: [PATCH] null_blk: Use strscpy() instead of strscpy_pad() in null_add

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Message-ID: <075de7dd-f3a2-4806-9e4c-9dfd38d12f69@linux.dev>
Date: Thu, 10 Apr 2025 18:11:42 +0200
From: Zhu Yanjun <yanjun.zhu@...ux.dev>
To: Thorsten Blum <thorsten.blum@...ux.dev>, Jens Axboe <axboe@...nel.dk>,
 Damien Le Moal <dlemoal@...nel.org>, Chaitanya Kulkarni <kch@...dia.com>,
 Johannes Thumshirn <johannes.thumshirn@....com>,
 Shin'ichiro Kawasaki <shinichiro.kawasaki@....com>,
 Zheng Qixing <zhengqixing@...wei.com>, Yu Kuai <yukuai3@...wei.com>
Cc: linux-block@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] null_blk: Use strscpy() instead of strscpy_pad() in
 null_add_dev()


On 10.04.25 17:47, Thorsten Blum wrote:
> blk_mq_alloc_disk() already zero-initializes the destination buffer,
> making strscpy() sufficient for safely copying the disk's name. The
> additional NUL-padding performed by strscpy_pad() is unnecessary.
>
> If the destination buffer has a fixed length, strscpy() automatically

Looks good to me. The destination buffer is indeed has a fixed length, 
it is DISK_NAME_LEN.

Reviewed-by: Zhu Yanjun <yanjun.zhu@...ux.dev>

Zhu Yanjun

> determines its size using sizeof() when the argument is omitted. This
> makes the explicit size argument unnecessary.
>
> The source string is also NUL-terminated and meets the __must_be_cstr()
> requirement of strscpy().
>
> No functional changes intended.
>
> Signed-off-by: Thorsten Blum <thorsten.blum@...ux.dev>
> ---
>   drivers/block/null_blk/main.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
> index 3bb9cee0a9b5..aa163ae9b2aa 100644
> --- a/drivers/block/null_blk/main.c
> +++ b/drivers/block/null_blk/main.c
> @@ -2031,7 +2031,7 @@ static int null_add_dev(struct nullb_device *dev)
>   	nullb->disk->minors = 1;
>   	nullb->disk->fops = &null_ops;
>   	nullb->disk->private_data = nullb;
> -	strscpy_pad(nullb->disk->disk_name, nullb->disk_name, DISK_NAME_LEN);
> +	strscpy(nullb->disk->disk_name, nullb->disk_name);
>   
>   	if (nullb->dev->zoned) {
>   		rv = null_register_zoned_dev(nullb);

-- 
Best Regards,
Yanjun.Zhu