Alan Cox wrote:
>
> On Wed, 2002-11-20 at 21:00, Luben Tuikov wrote:sk) {
> > > > - unsigned long duration = jiffies - req->start_time;
> > > > + unsigned long duration = (signed) jiffies - (signed) req->start_time;
> > > > switch (rq_data_dir(req)) {
> > >
> > > It was right before. Your patch breaks it. Think about it in unsigned
> > > maths
> > >
> > > 0x00000002 - 0xFFFFFFFF = 0x00000003
> >
> > 0x2 - (-0x1) = 0x2 + 0x1 = 0x3
> >
> > Right! I thought (signed) does the job. I actually tried
> > it both ways and works all right. I guess either way works fine.
>
> (signed long) maybe - but not signed - long is 64bit on Alpha, (signed)
> is 32
Aaaah, I see where you're coming from.
I basically tried to stay away from knowing _what_ actual
type it is and just to make it signed and do the arithmetic,
but didn't know the specific for the Alpha.
Shouldn't this be (symbolically:) (signed (typeof(jiffes)) jiffies -
(signed (typeof(start)) start -- you know what I mean.
But yes both ways should work:
a, b are both unsigned, then a-b = a+(-b) and there's just no
other way to compute the result.
Anyway, doesn't matter,
-- Luben - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Sat Nov 23 2002 - 22:00:33 EST