[PATCH] namespace: Replace simple_strtoul with kstrtoul to parse boot params

[PATCH] namespace: Replace simple_strtoul with kstrtoul to parse boot params

[Thorsten Blum]

Replace simple_strtoul() with the recommended kstrtoul() for parsing the
'mhash_entries=' and 'mphash_entries=' boot parameters.

Check the return value of kstrtoul() and reject invalid values. This
adds error handling while preserving behavior for existing values, and
removes use of the deprecated simple_strtoul() helper.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
 fs/namespace.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/fs/namespace.c b/fs/namespace.c
index c58674a20cad..a548369ddb9c 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -49,20 +49,14 @@ static unsigned int mp_hash_shift __ro_after_init;
 static __initdata unsigned long mhash_entries;
 static int __init set_mhash_entries(char *str)
 {
-	if (!str)
-		return 0;
-	mhash_entries = simple_strtoul(str, &str, 0);
-	return 1;
+	return kstrtoul(str, 0, &mhash_entries) == 0;
 }
 __setup("mhash_entries=", set_mhash_entries);
 
 static __initdata unsigned long mphash_entries;
 static int __init set_mphash_entries(char *str)
 {
-	if (!str)
-		return 0;
-	mphash_entries = simple_strtoul(str, &str, 0);
-	return 1;
+	return kstrtoul(str, 0, &mphash_entries) == 0;
 }
 __setup("mphash_entries=", set_mphash_entries);
 
-- 
Thorsten Blum <thorsten.blum@linux.dev>
GPG: 1D60 735E 8AEF 3BE4 73B6  9D84 7336 78FD 8DFE EAD4

Re: [PATCH] namespace: Replace simple_strtoul with kstrtoul to parse boot params

[Jan Kara]

On Sun 14-12-25 16:31:42, Thorsten Blum wrote:
> Replace simple_strtoul() with the recommended kstrtoul() for parsing the
> 'mhash_entries=' and 'mphash_entries=' boot parameters.
> 
> Check the return value of kstrtoul() and reject invalid values. This
> adds error handling while preserving behavior for existing values, and
> removes use of the deprecated simple_strtoul() helper.
> 
> Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>

...

> @@ -49,20 +49,14 @@ static unsigned int mp_hash_shift __ro_after_init;
>  static __initdata unsigned long mhash_entries;
>  static int __init set_mhash_entries(char *str)
>  {
> -	if (!str)
> -		return 0;
> -	mhash_entries = simple_strtoul(str, &str, 0);
> -	return 1;
> +	return kstrtoul(str, 0, &mhash_entries) == 0;
>  }
>  __setup("mhash_entries=", set_mhash_entries);

I'm not very experienced with the cmdline option parsing but AFAICT the
'str' argument can be indeed NULL and kstrtoul() will not be happy with
that?

>  static __initdata unsigned long mphash_entries;
>  static int __init set_mphash_entries(char *str)
>  {
> -	if (!str)
> -		return 0;
> -	mphash_entries = simple_strtoul(str, &str, 0);
> -	return 1;
> +	return kstrtoul(str, 0, &mphash_entries) == 0;
>  }
>  __setup("mphash_entries=", set_mphash_entries);

Similar here.

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

Re: [PATCH] namespace: Replace simple_strtoul with kstrtoul to parse boot params

[Thorsten Blum]

On 15. Dec 2025, at 10:15, Jan Kara wrote:
> On Sun 14-12-25 16:31:42, Thorsten Blum wrote:
>> Replace simple_strtoul() with the recommended kstrtoul() for parsing the
>> 'mhash_entries=' and 'mphash_entries=' boot parameters.
>> 
>> Check the return value of kstrtoul() and reject invalid values. This
>> adds error handling while preserving behavior for existing values, and
>> removes use of the deprecated simple_strtoul() helper.
>> 
>> Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
> 
> ...
> 
>> @@ -49,20 +49,14 @@ static unsigned int mp_hash_shift __ro_after_init;
>> static __initdata unsigned long mhash_entries;
>> static int __init set_mhash_entries(char *str)
>> {
>> -	if (!str)
>> -		return 0;
>> -	mhash_entries = simple_strtoul(str, &str, 0);
>> -	return 1;
>> +	return kstrtoul(str, 0, &mhash_entries) == 0;
>> }
>> __setup("mhash_entries=", set_mhash_entries);
> 
> I'm not very experienced with the cmdline option parsing but AFAICT the
> 'str' argument can be indeed NULL and kstrtoul() will not be happy with
> that?

I don't think 'str' can be NULL. If you don't pass a value, 'str' will
be the empty string (just tested this).

Thanks,
Thorsten

Re: [PATCH] namespace: Replace simple_strtoul with kstrtoul to parse boot params

[Jan Kara]

On Mon 15-12-25 15:17:14, Thorsten Blum wrote:
> On 15. Dec 2025, at 10:15, Jan Kara wrote:
> > On Sun 14-12-25 16:31:42, Thorsten Blum wrote:
> >> Replace simple_strtoul() with the recommended kstrtoul() for parsing the
> >> 'mhash_entries=' and 'mphash_entries=' boot parameters.
> >> 
> >> Check the return value of kstrtoul() and reject invalid values. This
> >> adds error handling while preserving behavior for existing values, and
> >> removes use of the deprecated simple_strtoul() helper.
> >> 
> >> Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
> > 
> > ...
> > 
> >> @@ -49,20 +49,14 @@ static unsigned int mp_hash_shift __ro_after_init;
> >> static __initdata unsigned long mhash_entries;
> >> static int __init set_mhash_entries(char *str)
> >> {
> >> -	if (!str)
> >> -		return 0;
> >> -	mhash_entries = simple_strtoul(str, &str, 0);
> >> -	return 1;
> >> +	return kstrtoul(str, 0, &mhash_entries) == 0;
> >> }
> >> __setup("mhash_entries=", set_mhash_entries);
> > 
> > I'm not very experienced with the cmdline option parsing but AFAICT the
> > 'str' argument can be indeed NULL and kstrtoul() will not be happy with
> > that?
> 
> I don't think 'str' can be NULL. If you don't pass a value, 'str' will
> be the empty string (just tested this).

Ah, ok. The NULL value can happen only for early parameters and for
arguments without '=' sign in the name. So I'm retracting my objection and
feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>


								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

Re: [PATCH] namespace: Replace simple_strtoul with kstrtoul to parse boot params

[Christian Brauner]

On Sun, 14 Dec 2025 16:31:42 +0100, Thorsten Blum wrote:
> Replace simple_strtoul() with the recommended kstrtoul() for parsing the
> 'mhash_entries=' and 'mphash_entries=' boot parameters.
> 
> Check the return value of kstrtoul() and reject invalid values. This
> adds error handling while preserving behavior for existing values, and
> removes use of the deprecated simple_strtoul() helper.
> 
> [...]

Applied to the vfs-7.0.misc branch of the vfs/vfs.git tree.
Patches in the vfs-7.0.misc branch should appear in linux-next soon.

Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.

It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.

Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. If in doubt, please check the listed branch.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: vfs-7.0.misc

[1/1] namespace: Replace simple_strtoul with kstrtoul to parse boot params
      https://git.kernel.org/vfs/vfs/c/3f320e5c2eca