mm/thp: use conventional format for boolean attributes

The conventional format for boolean attributes in sysfs is numeric ("0" or
"1" followed by new-line).  Any boolean attribute can then be read and
written using a generic function.  Using the strings "yes [no]", "[yes]
no" (read), "yes" and "no" (write) will frustrate this.

[akpm@linux-foundation.org: use kstrtoul()]
[akpm@linux-foundation.org: test_bit() doesn't return 1/0, per Neil]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Tested-by: David Rientjes <rientjes@google.com>
Cc: NeilBrown <neilb@suse.de>
Cc: <stable@kernel.org> 	[2.6.38.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 14 insertions, 10 deletions

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 1722683bde23..470dcda10add 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -244,24 +244,28 @@ static ssize_t single_flag_show(struct kobject *kobj,
                                 struct kobj_attribute *attr, char *buf,
                                 enum transparent_hugepage_flag flag)
 {
-        if (test_bit(flag, &transparent_hugepage_flags))
-                return sprintf(buf, "[yes] no\n");
-        else
-                return sprintf(buf, "yes [no]\n");
+        return sprintf(buf, "%d\n",
+                       !!test_bit(flag, &transparent_hugepage_flags));
 }
+
 static ssize_t single_flag_store(struct kobject *kobj,
                                  struct kobj_attribute *attr,
                                  const char *buf, size_t count,
                                  enum transparent_hugepage_flag flag)
 {
-        if (!memcmp("yes", buf,
-                    min(sizeof("yes")-1, count))) {
+        unsigned long value;
+        int ret;
+
+        ret = kstrtoul(buf, 10, &value);
+        if (ret < 0)
+                return ret;
+        if (value > 1)
+                return -EINVAL;
+
+        if (value)
                 set_bit(flag, &transparent_hugepage_flags);
-        } else if (!memcmp("no", buf,
-                           min(sizeof("no")-1, count))) {
+        else
                 clear_bit(flag, &transparent_hugepage_flags);
-        } else
-                return -EINVAL;
 
         return count;
 }