[PATCH] mm/slub: avoid double string traverse in kmem_cache_flags()

[PATCH] mm/slub: avoid double string traverse in kmem_cache_flags()

[Yury Norov]

If ',' is not found, kmem_cache_flags() calls strlen() to find the end
of line. We can do it in a single pass using strchrnul().

Signed-off-by: Yury Norov <ynorov@marvell.com>
---
 mm/slub.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 4922a0394757..85f90370a293 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1317,9 +1317,7 @@ slab_flags_t kmem_cache_flags(unsigned int object_size,
 		char *end, *glob;
 		size_t cmplen;
 
-		end = strchr(iter, ',');
-		if (!end)
-			end = iter + strlen(iter);
+		end = strchrnul(iter, ',');
 
 		glob = strnchr(iter, end - iter, '*');
 		if (glob)
-- 
2.17.1

Re: [PATCH] mm/slub: avoid double string traverse in kmem_cache_flags()

[Yury Norov]

On Tue, Apr 30, 2019 at 10:31:11PM -0700, Yury Norov wrote:
> If ',' is not found, kmem_cache_flags() calls strlen() to find the end
> of line. We can do it in a single pass using strchrnul().

Ping?

> Signed-off-by: Yury Norov <ynorov@marvell.com>
> ---
>  mm/slub.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/mm/slub.c b/mm/slub.c
> index 4922a0394757..85f90370a293 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -1317,9 +1317,7 @@ slab_flags_t kmem_cache_flags(unsigned int object_size,
>  		char *end, *glob;
>  		size_t cmplen;
>  
> -		end = strchr(iter, ',');
> -		if (!end)
> -			end = iter + strlen(iter);
> +		end = strchrnul(iter, ',');
>  
>  		glob = strnchr(iter, end - iter, '*');
>  		if (glob)
> -- 
> 2.17.1

Re: [PATCH] mm/slub: avoid double string traverse in kmem_cache_flags()

[Aaron Tomlin]

On Tue 2019-04-30 22:31 -0700, Yury Norov wrote:
> If ',' is not found, kmem_cache_flags() calls strlen() to find the end
> of line. We can do it in a single pass using strchrnul().
> 
> Signed-off-by: Yury Norov <ynorov@marvell.com>
> ---
>  mm/slub.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/mm/slub.c b/mm/slub.c
> index 4922a0394757..85f90370a293 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -1317,9 +1317,7 @@ slab_flags_t kmem_cache_flags(unsigned int object_size,
>  		char *end, *glob;
>  		size_t cmplen;
>  
> -		end = strchr(iter, ',');
> -		if (!end)
> -			end = iter + strlen(iter);
> +		end = strchrnul(iter, ',');
>  
>  		glob = strnchr(iter, end - iter, '*');
>  		if (glob)

Fair enough.

Acked-by: Aaron Tomlin <atomlin@redhat.com>

-- 
Aaron Tomlin