[PATCH] lib/parser.c: switch match_strdup() over to use kmemdup_nul()

[PATCH] lib/parser.c: switch match_strdup() over to use kmemdup_nul()

[Eric Biggers]

From: Eric Biggers <ebiggers@google.com>

This simplifies the code.  No change in behavior.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 lib/parser.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/lib/parser.c b/lib/parser.c
index 3278958b472a..0142ef28f0eb 100644
--- a/lib/parser.c
+++ b/lib/parser.c
@@ -327,10 +327,6 @@ EXPORT_SYMBOL(match_strlcpy);
  */
 char *match_strdup(const substring_t *s)
 {
-	size_t sz = s->to - s->from + 1;
-	char *p = kmalloc(sz, GFP_KERNEL);
-	if (p)
-		match_strlcpy(p, s, sz);
-	return p;
+	return kmemdup_nul(s->from, s->to - s->from, GFP_KERNEL);
 }
 EXPORT_SYMBOL(match_strdup);
-- 
2.19.0.rc0.228.g281dcd1b4d0-goog

Re: [PATCH] lib/parser.c: switch match_strdup() over to use kmemdup_nul()

[Andrew Morton]

On Thu, 30 Aug 2018 12:44:36 -0700 Eric Biggers <ebiggers@kernel.org> wrote:

> From: Eric Biggers <ebiggers@google.com>
> 
> This simplifies the code.  No change in behavior.
> 
> ...
>
> --- a/lib/parser.c
> +++ b/lib/parser.c
> @@ -327,10 +327,6 @@ EXPORT_SYMBOL(match_strlcpy);
>   */
>  char *match_strdup(const substring_t *s)
>  {
> -	size_t sz = s->to - s->from + 1;
> -	char *p = kmalloc(sz, GFP_KERNEL);
> -	if (p)
> -		match_strlcpy(p, s, sz);
> -	return p;
> +	return kmemdup_nul(s->from, s->to - s->from, GFP_KERNEL);
>  }
>  EXPORT_SYMBOL(match_strdup);

Huh.  I never noticed kmemdup_nul() fly past - it rather happened on
the sly.  We do have some fun goodies in there.

We could make match_strdup() an inline now.  But that will probably
produce a fatter kernel, as each callsite would then need to prepare
three args rather than one.