Re: [win-pv-devel] Xenbus hashtable usage

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: RafaÅ WojdyÅa [mailto:omeg@xxxxxxxxxxxxxxxxxxxxxx]
> Sent: 09 September 2015 10:59
> To: Paul Durrant; win-pv-devel@xxxxxxxxxxxxxxxxxxxx
> Subject: Re: [win-pv-devel] Xenbus hashtable usage
> 
> On 2015-09-09 11:51, Paul Durrant wrote:
> >> -----Original Message-----
> >> From: win-pv-devel-bounces@xxxxxxxxxxxxxxxxxxxx [mailto:win-pv-devel-
> >> bounces@xxxxxxxxxxxxxxxxxxxx] On Behalf Of Paul Durrant
> >> Sent: 09 September 2015 10:18
> >> To: RafaÅ WojdyÅa; win-pv-devel@xxxxxxxxxxxxxxxxxxxx
> >> Subject: Re: [win-pv-devel] Xenbus hashtable usage
> >>
> >>> -----Original Message-----
> >>> From: RafaÅ WojdyÅa [mailto:omeg@xxxxxxxxxxxxxxxxxxxxxx]
> >>> Sent: 09 September 2015 10:17
> >>> To: Paul Durrant; win-pv-devel@xxxxxxxxxxxxxxxxxxxx
> >>> Subject: Re: [win-pv-devel] Xenbus hashtable usage
> >>>
> >>> On 2015-09-09 10:34, Paul Durrant wrote:
> >>>>> -----Original Message-----
> >>>>> From: win-pv-devel-bounces@xxxxxxxxxxxxxxxxxxxx [mailto:win-pv-
> >> devel-
> >>>>> bounces@xxxxxxxxxxxxxxxxxxxx] On Behalf Of Rafal Wojdyla
> >>>>> Sent: 09 September 2015 01:44
> >>>>> To: win-pv-devel@xxxxxxxxxxxxxxxxxxxx
> >>>>> Subject: [win-pv-devel] Xenbus hashtable usage
> >>>>>
> >>>>> Is the hash table from hash_table.c supposed to accept arbitrary key
> >>>>> values?
> >>
> >> Ok, cool. I'll get a fix together a.s.a.p.
> >>
> >
> > I think this should do it:
> >
> > diff --git a/src/xenbus/hash_table.c b/src/xenbus/hash_table.c
> > index a9c1b79..c7c6101 100644
> > --- a/src/xenbus/hash_table.c
> > +++ b/src/xenbus/hash_table.c
> > @@ -90,7 +90,7 @@ HashTableHash(
> >
> >          Accumulator = (Accumulator << 4) + Array[Index];
> >
> > -        Overflow = Accumulator & 0x00000f00;
> > +        Overflow = Accumulator & 0x0000ff00;
> >          if (Overflow != 0) {
> >              Accumulator ^= Overflow >> 8;
> >              Accumulator ^= Overflow;
> >
> > Can you test?
> >
> >   Paul
> >
> This indeed seems to fix the issue, thanks.
> 

Cool. Proper patch in a short while then :-)

  Paul

> >>   Paul
> >>
> >>>>
> >>>> That's the idea. What are you intending to do with it? I have been
> >>> wondering about exposing it as an interface.
> >>>>
> >>> I wanted to use it for storing address <-> map handles for gnttab as you
> >>> suggested.
> >>>
> >>>>> I've been tripping the assertion in HashTableHash() on keys that
> >>>>> were 64bit addresses.
> >>>>>
> >>>>
> >>>> That sounds like a straightforward bug then. I'll have a look.
> >>>>
> >>>> Cheers,
> >>>>
> >>>>     Paul
> >>>>
> 
> 
> --
> RafaÅ WojdyÅa
> Qubes Tools for Windows developer
> https://www.qubes-os.org/
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