On Fri, Jul 07, 2017 at 08:18:20PM +0200, Igor Mammedov wrote: > On Fri, 7 Jul 2017 12:09:56 -0300 > Eduardo Habkost <ehabk...@redhat.com> wrote: > > > On Fri, Jul 07, 2017 at 04:58:17PM +0200, Igor Mammedov wrote: > > > On Fri, 7 Jul 2017 10:13:00 -0300 > > > "Eduardo Habkost" <ehabk...@redhat.com> wrote: > > [...] > > > > I don't disagree with adding the assert(), but it looks like > > > > making fw_cfg_find() return NULL if there are multiple devices > > > > can be useful for realize. > > > > > > > > In this case, it looks like Mark is relying on that in > > > > fw_cfg_common_realize(): if multiple devices are created, > > > > fw_cfg_find() will return NULL, and realize will fail. This > > > > sounds like a more graceful way to handle multiple-device > > > > creation than crashing on fw_cfg_find(). This is the solution > > > > used by find_vmgenid_dev()/vmgenid_realize(), BTW. > > > > > > I suspect that find_vmgenid_dev() works by luck as it could be > > > placed only as /machine/peripheral-anon/foo1 or /machine/peripheral/foo2 > > > object_resolve_partial_path() : machine > > > object_resolve_partial_path() : peripheral-anon => foo1 > > > object_resolve_partial_path() : peripheral => foo2 > > > if (found /* foo2 */) { > > > if (obj /* foo1 */) { > > > return NULL; > > > > I don't think this is luck: object_resolve_partial_path() is > > explicitly documented to always return NULL if multiple matches > > are found, and I don't see any bug in its implementation that > > would break that functionality. > > Maybe I'm reading it wrong, but consider following: > https://www.mail-archive.com/qemu-devel@nongnu.org/msg460692.html > > it looks to me that using ambiguous argument is necessary for > duplicate detection to work correctly.
Oh, good catch, I think I see the bug now. We need to write a test case and fix that. -- Eduardo