Re: [KJ] [PATCH] is_power_of_2 in ia64mm

On Fri, 16 Feb 2007, Richard Knutsson wrote:

Andreas Schwab wrote:
Richard Knutsson <ricknu-0@xxxxxxxxxxxxxx> writes:


Vignesh Babu BM wrote:

@@ -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.

size == 0 is also covered by the next two conditions, so the
overall value does not change.

Yes, but is it meant to state that 'size' is not a power of two?
Otherwise, imho, it should be left as-is.

i think the above change is fine. as long as the final, overall
semantics of the condition are identical, then there's no problem.

rday

--
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Robert P. J. Day
Linux Consulting, Training and Annoying Kernel Pedantry
Waterloo, Ontario, CANADA

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