On 03/17/2015 05:56 AM, Stefan Hajnoczi wrote: > The binary search in sdp_uuid_match() only works when the number of > elements to search is a power of two. > > lo = record->uuid; > hi = record->uuids; > while (hi >>= 1) > if (lo[hi] <= val) > lo += hi; > > return *lo == val; > > I noticed that the record->uuids calculation in > sdp_service_record_build() was suspect: > > record->uuids = 1 << ffs(record->uuids - 1); > > Unlike most ffs(val) - 1 users, the expression is ffs(val - 1)!
Indeed, quite likely to be quite wrong. > > Actually ffs() is the wrong function to use for power-of-2. Use > pow2ceil() to achieve the correct effect. Now the record->uuid[] array > is sized correctly and the binary search in sdp_uuid_match() should > work. > > I'm not sure how to run/test this code. Me neither. But I can still analyze the code for sanity. Counts as a bug fix, so I'd put this in 2.3, even if the rest of the series is deferred to 2.4 as being a style cleanup rather than bug fix. > > Cc: Andrzej Zaborowski <bal...@zabor.org> > Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com> > --- > hw/bt/sdp.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Reviewed-by: Eric Blake <ebl...@redhat.com> -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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