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ubifs: correct UBIFS_DFS_DIR_LEN macro definition and improve code clarity

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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 31 (2 characters), and volume ID ranges from 0 to 127 (up
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.

While these changes do not affect the runtime behavior, they make the code
more readable, maintainable, and less prone to future errors.

v2->v3:

 - 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.

Signed-off-by: ZhaoLong Wang <wangzhaolong1@huawei.com>
Reviewed-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
This commit is contained in:
ZhaoLong Wang 2024-04-18 15:07:04 +08:00 committed by Richard Weinberger
parent 72f3d3dadd
commit 7037c96d8c
6 changed files with 12 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
drivers/mtd/ubi/debug.c
View File

@ -598,9 +598,9 @@ int ubi_debugfs_init_dev(struct ubi_device *ubi)
if (!IS_ENABLED(CONFIG_DEBUG_FS))
return 0;
n = snprintf(d->dfs_dir_name, UBI_DFS_DIR_LEN + 1, UBI_DFS_DIR_NAME,
n = snprintf(d->dfs_dir_name, UBI_DFS_DIR_LEN, UBI_DFS_DIR_NAME,
ubi->ubi_num);
if (n > UBI_DFS_DIR_LEN) {
if (n >= UBI_DFS_DIR_LEN) {
/* The array size is too small */
return -EINVAL;
}

2
drivers/mtd/ubi/ubi.h
View File

@ -420,7 +420,7 @@ struct ubi_debug_info {
unsigned int power_cut_min;
unsigned int power_cut_max;
unsigned int emulate_failures;
char dfs_dir_name[UBI_DFS_DIR_LEN + 1];
char dfs_dir_name[UBI_DFS_DIR_LEN];
struct dentry *dfs_dir;
struct dentry *dfs_chk_gen;
struct dentry *dfs_chk_io;

4
fs/ubifs/debug.c
View File

@ -2827,9 +2827,9 @@ void dbg_debugfs_init_fs(struct ubifs_info *c)
const char *fname;
struct ubifs_debug_info *d = c->dbg;
n = snprintf(d->dfs_dir_name, UBIFS_DFS_DIR_LEN + 1, UBIFS_DFS_DIR_NAME,
n = snprintf(d->dfs_dir_name, UBIFS_DFS_DIR_LEN, UBIFS_DFS_DIR_NAME,
c->vi.ubi_num, c->vi.vol_id);
if (n > UBIFS_DFS_DIR_LEN) {
if (n >= UBIFS_DFS_DIR_LEN) {
/* The array size is too small */
return;
}

7
fs/ubifs/debug.h
View File

@ -19,10 +19,11 @@ typedef int (*dbg_znode_callback)(struct ubifs_info *c,
/*
* The UBIFS debugfs directory name pattern and maximum name length (3 for "ubi"
* + 1 for "_" and plus 2x2 for 2 UBI numbers and 1 for the trailing zero byte.
* + 1 for "_" and 2 for UBI device numbers and 3 for volume number and 1 for
* the trailing zero byte.
*/
#define UBIFS_DFS_DIR_NAME "ubi%d_%d"
#define UBIFS_DFS_DIR_LEN (3 + 1 + 2*2 + 1)
#define UBIFS_DFS_DIR_LEN (3 + 1 + 2 + 3 + 1)
/**
* ubifs_debug_info - per-FS debugging information.
@ -103,7 +104,7 @@ struct ubifs_debug_info {
unsigned int chk_fs:1;
unsigned int tst_rcvry:1;
char dfs_dir_name[UBIFS_DFS_DIR_LEN + 1];
char dfs_dir_name[UBIFS_DFS_DIR_LEN];
struct dentry *dfs_dir;
struct dentry *dfs_dump_lprops;
struct dentry *dfs_dump_budg;

6
fs/ubifs/sysfs.c
View File

@ -91,17 +91,17 @@ static struct kset ubifs_kset = {
int ubifs_sysfs_register(struct ubifs_info *c)
{
int ret, n;
char dfs_dir_name[UBIFS_DFS_DIR_LEN+1];
char dfs_dir_name[UBIFS_DFS_DIR_LEN];
c->stats = kzalloc(sizeof(struct ubifs_stats_info), GFP_KERNEL);
if (!c->stats) {
ret = -ENOMEM;
goto out_last;
}
n = snprintf(dfs_dir_name, UBIFS_DFS_DIR_LEN + 1, UBIFS_DFS_DIR_NAME,
n = snprintf(dfs_dir_name, UBIFS_DFS_DIR_LEN, UBIFS_DFS_DIR_NAME,
c->vi.ubi_num, c->vi.vol_id);
if (n > UBIFS_DFS_DIR_LEN) {
if (n >= UBIFS_DFS_DIR_LEN) {
/* The array size is too small */
ret = -EINVAL;
goto out_free;

7
fs/ubifs/ubifs.h
View File

@ -157,13 +157,6 @@
#define UBIFS_HMAC_ARR_SZ 0
#endif
/*
* The UBIFS sysfs directory name pattern and maximum name length (3 for "ubi"
* + 1 for "_" and plus 2x2 for 2 UBI numbers and 1 for the trailing zero byte.
*/
#define UBIFS_DFS_DIR_NAME "ubi%d_%d"
#define UBIFS_DFS_DIR_LEN (3 + 1 + 2*2 + 1)
/*
* Lockdep classes for UBIFS inode @ui_mutex.
*/