Re: [KJ] [PATCH] is_power_of_2 in ia64mm

Vignesh Babu BM wrote:
Replacing (n & (n-1)) in the context of power of 2 checks
with is_power_of_2


diff --git a/arch/ia64/mm/hugetlbpage.c b/arch/ia64/mm/hugetlbpage.c
index 0c7e94e..0ccc70e 100644
--- a/arch/ia64/mm/hugetlbpage.c
+++ b/arch/ia64/mm/hugetlbpage.c
@@ -16,6 +16,7 @@
#include <linux/smp_lock.h>
#include <linux/slab.h>
#include <linux/sysctl.h>
+#include <linux/log2.h>
#include <asm/mman.h>
#include <asm/pgalloc.h>
#include <asm/tlb.h>
@@ -175,7 +176,7 @@ static int __init hugetlb_setup_sz(char *str)
tr_pages = 0x15557000UL;
size = memparse(str, &str);
- if (*str || (size & (size-1)) || !(tr_pages & size) ||
+ if (*str || !is_power_of_2(size) || !(tr_pages & size) ||
size <= PAGE_SIZE ||
size >= (1UL << PAGE_SHIFT << MAX_ORDER)) {
printk(KERN_WARNING "Invalid huge page size specified\n");

As we talked about before; is this really correct? !is_power_of_2(0) == true while (0 & (0-1)) == 0.

Richard Knutsson

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