Wireshark-bugs: [Wireshark-bugs] [Bug 13202] RPC-over-RDMA dissector no longer identifies any va
Comment # 12
on bug 13202
from Chuck Lever
(In reply to Parav Pandit from comment #11)
> (In reply to Chuck Lever from comment #8)
> > Just as a data point, I applied the packet-infiniband.c diff from change
> > 19107 on top of my tree with conversation logic removed from
> > packet-rpcrdma.c. It does not change the behavior of the RPC dissector.
> >
> Sorry, I didn't follow. Do you see them as Infiniband frames or as
> RPC/PortMap/NFS frames after applying my patch?
>
> With the pcap trace of bug 13213, with my change 19107 I am able to see them
> as NFS/RPC frames.
Before changing anything, only the raw InfiniBand traffic appeared.
After removing the find_or_create_conversation() call site from
packet-rpcrdma.c as 19107 does, RPC Calls were properly decoded as NFS
requests, but RPC Replies appeared as "RPC ### V0 proc-0 Reply". This means the
RPC dissector was not able to match the XID of each Reply to a previous Call
message.
Though this is still broken, this is the until-now normal behavior for
RPC-over-RDMA, up until the "remove duplicate conversations from
packet-infiniband.c" patch. In a capture of NFS on IPoIB or NFS on TCP, you
will see the proper expected way NFS Replies are supposed to appear.
After I applied the packet-infiniband.c hunk of 19107, nothing changed.
Thus my humble conclusion is that the packet-rpcrdma.c hunk of 19107 is the
part that fixes the regression introduced by "remove duplication conversations"
. The packet-infiniband.c hunk does not appear to change the behavior of either
the RPC or RPC-over-RDMA dissector.
> > I've filed bug 13213 to separately document the RPC reply dissection failure.
I'll attach my fix to 13213, and we can compare and discuss both approaches. I
see why fixing packet-infiniband.c might affect more ULP dissectors, and thus
it might be a more broad fix. Getting PT_IBQP and PT_TCP conversations to
behave more alike is probably a desirable long-term goal. But 19107 is either
not quite right, or somehow it is not enough for RPC. (Probably the latter).
It may be that the packet-infiniband.c hunk of 19107 is still appropriate to
apply. I just wanted to note, however, that change by itself does not appear to
address either 13202 or 13213 (unless I've done something wrong).
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