mm: hugetlb_vmemmap: use kstrtobool for hugetlb_vmemmap param parsing

Use kstrtobool rather than open coding "on" and "off" parsing in
mm/hugetlb_vmemmap.c, which is more powerful to handle all kinds of
parameters like 'Yy1Nn0' or [oO][NnFf] for "on" and "off".

Link: https://lkml.kernel.org/r/20220512041142.39501-4-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index d9b577d..7e079b6 100644 (file)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1664,10 +1664,10 @@
                        enabled.
                        Allows heavy hugetlb users to free up some more
                        memory (7 * PAGE_SIZE for each 2MB hugetlb page).
-                       Format: { on | off (default) }
+                       Format: { [oO][Nn]/Y/y/1 | [oO][Ff]/N/n/0 (default) }
 
-                       on:  enable the feature
-                       off: disable the feature
+                       [oO][Nn]/Y/y/1: enable the feature
+                       [oO][Ff]/N/n/0: disable the feature
 
                        Built with CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON=y,
                        the default is on.

diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
index 6254bb2..cc4ec75 100644 (file)
--- a/mm/hugetlb_vmemmap.c
+++ b/mm/hugetlb_vmemmap.c
@@ -28,15 +28,15 @@ EXPORT_SYMBOL(hugetlb_optimize_vmemmap_key);
 
 static int __init hugetlb_vmemmap_early_param(char *buf)
 {
-       if (!buf)
+       bool enable;
+
+       if (kstrtobool(buf, &enable))
                return -EINVAL;
 
-       if (!strcmp(buf, "on"))
+       if (enable)
                static_branch_enable(&hugetlb_optimize_vmemmap_key);
-       else if (!strcmp(buf, "off"))
-               static_branch_disable(&hugetlb_optimize_vmemmap_key);
        else
-               return -EINVAL;
+               static_branch_disable(&hugetlb_optimize_vmemmap_key);
 
        return 0;
 }