On 19.11.18 20:51, Markus Armbruster wrote: > Copying Igor and Eduardo for a hostmem.c bug. Search for "core dumped". > > David Hildenbrand <da...@redhat.com> writes: > >>>> >>>> Tests have to be fixed up: >>>> - Two BUGs were hardcoded that are fixed now >>>> - The string-input-visitor now actually returns a parsed list and not >>>> an ordered set. >>> >>> I'd expect this to necessitate an update of callers that expect a set, >>> but... >>> >>>> Signed-off-by: David Hildenbrand <da...@redhat.com> >>>> --- >>>> include/qapi/string-input-visitor.h | 4 +- >>>> qapi/string-input-visitor.c | 410 ++++++++++++++++------------ >>>> tests/test-string-input-visitor.c | 18 +- >>>> 3 files changed, 239 insertions(+), 193 deletions(-) >>> >>> ... there's none. >>> >>> Let me know if you need help finding them. I think we tracked them down >>> during the discussion that led to this series. >>> >> >> Indeed, I missed to document that. So here is the outcome: >> >> 1. backends/hostmem.c:host_memory_backend_set_host_nodes() >> >> -> calls visit_type_uint16List(via bitmap) >> -> the code can deal with duplicates/unsorted lists (bitmap_set) > > Yes. > >> Side node: I am not sure if there should be some range checks, but maybe >> the bitmap is large enough .... hm ... > > Fishy. MAX_NODES is 128. Tinker, tinker, ... > > $ upstream-qemu -nodefaults -object > memory-backend-file,id=mem0,mem-path=x,size=4096,host-nodes=12345 > Segmentation fault (core dumped) > > Igor, Eduardo, this is yours. > > There's another use of visit_type_uint16List() is this file, but it's in > property getter host_memory_backend_get_host_nodes(), and property > getters aren't used with the string input visitor. > >> 2. qapi-visit.c::visit_type_Memdev_members() >> >> -> calls visit_type_uint16List() >> -> I think this never used for input, only for output / freeing > > Yes, it's used by query-memdev with the QObject output visitor to build > the value of @host-nodes. > >> 3. qapi-visit.c::visit_type_NumaNodeOptions_members() >> >> -> calls visit_type_uint16List() >> -> I think this never used for input, only for output / freeing > > It's used for input, but with the opts visitor, see parse_numa(). > >> 4. qapi-visit.c::visit_type_RockerOfDpaGroup_members >> >> -> calls visit_type_uint32List() >> -> I think this never used for input, only for output / freeing > > Yes, it's used by query-rocker-of-dpa-groups with the QObject output > visitor to build the value of @group-ids. > >> 5. qapi-visit.c::visit_type_RxFilterInfo_members() >> >> -> calls visit_type_intList() >> -> I think this never used for input, only for output / freeing > > Yes, it's used by query-rx-filter with the QObject output visitor to > build the value of @vlan-table. > >> 6. numa.c::query_memdev() >> >> -> calls object_property_get_uint16List() >> --> String parsed via visit_type_uint16List() into list > > QOM, hard to understand. > > The value of struct HostMemoryBackend member @host-nodes (a bitmap) is > first converted to a list (sorted, no duplicates) with > host_memory_backend_get_host_nodes() via object_property_get(), then > converted to a string with the string output visitor. The resulting > string is then converted back to a list with the string input visitor. > > Despite the shenanigans going on in the string output visitor, I'd > expect the resulting list to also be sorted and without duplicates. > >> -> qmp_query_memdev() uses this list >> --> Not relevant if unique or sorted > > Depends on the contract of QMP command query-memdev. Here's the > relevant part. > > # @host-nodes: host nodes for its memory policy > > Useless. > > "Sorted, no duplicates" might have become de facto ABI. Not sure. > However, I believe your patch won't affect it, as per the argument I > just made. > >> -> hmp_info_memdev() uses this list >> --> List converted again to a string using string output visitor >> >> -> I don't think unique/sorted is relevant here. > > HMP is not a stable interface. > >> Am I missing anything / is any of my statements wrong? > > Searching the QAPI schema for lists of integers coughs up block latency > histogram stuff, but that's unrelated, as far as I can tell. > > Looks like we're good. I didn't expect that :) >
Haha, me too. Will add a short description to the patch message and maybe resend tomorrow! -- Thanks, David / dhildenb
