linux-kernel - [PATCH] mm/slub: avoid double string traverse in kmem_cache

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Date:   Tue, 30 Apr 2019 22:31:11 -0700
From:   Yury Norov <yury.norov@...il.com>
To:     Aaron Tomlin <atomlin@...hat.com>,
        Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Yury Norov <ynorov@...vell.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Yury Norov <yury.norov@...il.com>
Subject: [PATCH] mm/slub: avoid double string traverse in kmem_cache_flags()

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@...vell.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