namespace: Replace simple_strtoul with kstrtoul to parse boot params

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>
Link: https://patch.msgid.link/20251214153141.218953-2-thorsten.blum@linux.dev
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>

Author: toblux

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);