Re: [KJ] [PATCH] is_power_of_2 in ia64mm

[Richard Knutsson <ricknu-0@student.ltu.se>]

Andreas Schwab wrote:
> Richard Knutsson <ricknu-0@student.ltu.se> writes:
>   
> > Andreas Schwab wrote:
> >     
> > > Richard Knutsson <ricknu-0@student.ltu.se> 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?
> >     
>
> What else can it mean?
>   
What about !one_or_less_bit()? It has not been implemented (yet?) but 
been discussed. It ended by concluding that is_power_of_2() should be 
fixed up first and then we can see about it.
And as I stated before; !is_power_of_2(size) != (size & (size-1))! It 
may be a bug but then we have to be sure it is suppose to be the power of 2.

Richard Knutsson

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