[PATCH] include/linux/slab.h: use for() and left shift to calculate

[Yejune Deng]

use for() and left shift to calculate the value that compared with size.

Signed-off-by: Yejune Deng <yejune.d...@gmail.com>
---
 include/linux/slab.h | 32 ++++++++------------------------
 1 file changed, 8 insertions(+), 24 deletions(-)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 7ae604076767..0411f57930fb 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -347,6 +347,8 @@ static __always_inline enum kmalloc_cache_type 
kmalloc_type(gfp_t flags)
  */
 static __always_inline unsigned int kmalloc_index(size_t size)
 {
+       int i;
+
        if (!size)
                return 0;
 
@@ -357,30 +359,12 @@ static __always_inline unsigned int kmalloc_index(size_t 
size)
                return 1;
        if (KMALLOC_MIN_SIZE <= 64 && size > 128 && size <= 192)
                return 2;
-       if (size <=          8) return 3;
-       if (size <=         16) return 4;
-       if (size <=         32) return 5;
-       if (size <=         64) return 6;
-       if (size <=        128) return 7;
-       if (size <=        256) return 8;
-       if (size <=        512) return 9;
-       if (size <=       1024) return 10;
-       if (size <=   2 * 1024) return 11;
-       if (size <=   4 * 1024) return 12;
-       if (size <=   8 * 1024) return 13;
-       if (size <=  16 * 1024) return 14;
-       if (size <=  32 * 1024) return 15;
-       if (size <=  64 * 1024) return 16;
-       if (size <= 128 * 1024) return 17;
-       if (size <= 256 * 1024) return 18;
-       if (size <= 512 * 1024) return 19;
-       if (size <= 1024 * 1024) return 20;
-       if (size <=  2 * 1024 * 1024) return 21;
-       if (size <=  4 * 1024 * 1024) return 22;
-       if (size <=  8 * 1024 * 1024) return 23;
-       if (size <=  16 * 1024 * 1024) return 24;
-       if (size <=  32 * 1024 * 1024) return 25;
-       if (size <=  64 * 1024 * 1024) return 26;
+
+       /* The maximum of size is 2^26 = 64 * 1024 * 1024 */
+       for (i = 3; i <= 26; i++) {
+               if (size <= (1 << i))
+                       return i;
+       }
        BUG();
 
        /* Will never be reached. Needed because the compiler may complain */
-- 
2.29.0