linux-kernel - Re: [PATCH V3] ubifs: correct UBIFS_DFS_DIR_LEN macro definition and improve code clarity

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Message-ID: <e4bd7fcd-f740-b2f1-ad20-63860db9fa38@huawei.com>
Date: Wed, 17 Apr 2024 19:22:13 +0800
From: Zhihao Cheng <chengzhihao1@...wei.com>
To: ZhaoLong Wang <wangzhaolong1@...wei.com>, <richard@....at>,
	<miquel.raynal@...tlin.com>, <vigneshr@...com>
CC: <linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
	<yi.zhang@...wei.com>, <yangerkun@...wei.com>
Subject: Re: [PATCH V3] ubifs: correct UBIFS_DFS_DIR_LEN macro definition and
 improve code clarity

在 2024/4/17 17:27, ZhaoLong Wang 写道:
> The UBIFS_DFS_DIR_LEN macro, which defines the maximum length of the UBIFS
> debugfs directory name, has an incorrect formula and misleading comments.
> The current formula is (3 + 1 + 2*2 + 1), which assumes that both UBI device
> number and volume ID are limited to 2 characters. However, UBI device number
> ranges from 0 to 37 (2 characters), and volume ID ranges from 0 to 127 (up

UBI device number ranges from 0~31? UBI_MAX_DEVICES(32)
> to 3 characters).
> 
> Although the current code works due to the cancellation of mathematical
> errors (9 + 1 = 10, which matches the correct UBIFS_DFS_DIR_LEN value), it
> can lead to confusion and potential issues in the future.
> 
> This patch aims to improve the code clarity and maintainability by making
> the following changes:
> 
> 1. Corrects the UBIFS_DFS_DIR_LEN macro definition to (3 + 1 + 2 + 3 + 1),
>     accommodating the maximum lengths of both UBI device number and volume ID,
>     plus the separators and null terminator.
> 2. Updates the snprintf calls to use UBIFS_DFS_DIR_LEN instead of
>     UBIFS_DFS_DIR_LEN + 1, removing the unnecessary +1.
> 3. Modifies the error checks to compare against UBIFS_DFS_DIR_LEN using >=
>     instead of >, aligning with the corrected macro definition.
> 4. Removes the redundant +1 in the dfs_dir_name array definitions in ubi.h
>     and debug.h.
> 5. Removes the duplicated UBIFS_DFS_DIR_LEN and UBIFS_DFS_DIR_NAME macro
>     definitions in ubifs.h, as they are already defined in debug.h.
> 
> While these changes do not affect the runtime behavior, they make the code
> more readable, maintainable, and less prone to future errors.
> 
> Signed-off-by: ZhaoLong Wang <wangzhaolong1@...wei.com>
> ---

Please add change log v2->v3 next time.
>   drivers/mtd/ubi/debug.c | 4 ++--
>   drivers/mtd/ubi/ubi.h   | 2 +-
>   fs/ubifs/debug.c        | 4 ++--
>   fs/ubifs/debug.h        | 7 ++++---
>   fs/ubifs/sysfs.c        | 6 +++---
>   fs/ubifs/ubifs.h        | 7 -------
>   6 files changed, 12 insertions(+), 18 deletions(-)

Reviewed-by: Zhihao Cheng <chengzhihao1@...wei.com>