11:11 a.m.
> > + unsigned long epfn = PFN_DOWN(epa);
> > + unsigned long spfn = PFN_UP(spa);
> > +
> > + /*
> > + * Verify the end is at least past the start of the zone and
> > + * that we have at least one PFN to initialize.
> > + */
> > + if (zone->zone_start_pfn < epfn && spfn < epfn) {
> > + /* if we went too far just stop searching */
> > + if (zone_end_pfn(zone) <= spfn)
> > + break;
>
> Set *idx = U64_MAX here, then break. This way after we are outside this
> while loop idx is always equals to U64_MAX.
Actually I think what you are asking for is the logic that is outside
of the while loop we are breaking out of. So if you check at the end of
the function there is the bit of code with the comment "signal end of
iteration" where I end up setting *idx to ULLONG_MAX, *out_spfn to
ULONG_MAX, and *out_epfn to 0.
The general idea I had with the function is that you could use either
the index or spfn < epfn checks to determine if you keep going or not.
Yes, I meant to remove that *idx = U64_MAX after the loop, it is
confusing to have a loop:
while (*idx != U64_MAX) {
...
}
*idx = U64_MAX;
So, it is better to set idx to U643_MAX inside the loop before the
break.
>
> > +
> > + if (out_spfn)
> > + *out_spfn = max(zone->zone_start_pfn, spfn);
> > + if (out_epfn)
> > + *out_epfn = min(zone_end_pfn(zone), epfn);
>
> Don't we need to verify after adjustment that out_spfn != out_epfn, so
> there is at least one PFN to initialize?
We have a few checks that I believe prevent that. Before we get to this
point we have verified the following:
zone->zone_start < epfn
spfn < epfn
The other check that should be helping to prevent that is the break
statement above that is forcing us to exit if spfn is somehow already
past the end of the zone, that essentially maps out:
spfn < zone_end_pfn(zone)
So the only check we don't have is:
zone->zone_start < zone_end_pfn(zone)
If I am not mistaken that is supposed to be a given is it not? I would
assume we don't have any zones that are completely empty or inverted
that would be called here do we?
if (zone_end_pfn(zone) <= spfn) won't break
Equal sign in <= here takes care of the case I was thinking. Yes, logic looks good.
Thank you
Pasha