Re: [libvirt] [PATCH 1/2] rpc: client: fix race on stream error and stream creation

On 2/15/19 9:10 AM, Nikolay Shirokovskiy wrote: > Message of API call that creates stream and stream itself have > same rpc serial. This can lead to issues. If stream got error > immediately after creation then notification can be delivered > before API call reply arrived. This is possible because the > reply and the error message are sent from different threads > (rpc worker thread and event loop thread respectively). As > we don't check for message type in virNetClientCallCompleteAllWaitingReply > we complete the API call which leads to API call error [1] > as there is no actual reply. Later when reply arrives connection > will be closed due to protocol error (see check in virNetClientCallDispatchReply). > Let's fix virNetClientCallCompleteAllWaitingReply. > > Queue inspection on arriving VIR_NET_CONTINUE message in > virNetClientCallDispatchStream is safe because there we check for > status field also. Queue inspection on arriving VIR_NET_OK is safe > too as this message can not arrive before we call virFinishAbort(Finish) > which is not possible before API call that creates streams returns. > But just to be sure let's add checking message type in these places too. > > [1] error: internal error: Unexpected message type 0 > > Signed-off-by: Nikolay Shirokovskiy <nshirokovskiy(a)virtuozzo.com&gt; > --- > src/rpc/virnetclient.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > The commit message was hard to read, but I know it's an english is not the first language type thing. > diff --git a/src/rpc/virnetclient.c b/src/rpc/virnetclient.c > index 64855fb..0393587 100644 > --- a/src/rpc/virnetclient.c > +++ b/src/rpc/virnetclient.c > @@ -1163,7 +1163,8 @@ static void virNetClientCallCompleteAllWaitingReply(virNetClientPtr client) > virNetClientCallPtr call; > > for (call = client->waitDispatch; call; call = call->next) { > - if (call->msg->header.prog == client->msg.header.prog && > + if (call->msg->header.type == VIR_NET_STREAM && What about VIR_NET_STREAM_HOLE ?

Hopefully someone with greater working knowledge of the processing of this code can help out here. I guess I'm just concerned about some odd processing case that may have expected to be called, but now wouldn't be because of this change. BTW: any thoughts to perhaps extracting out the common parts between the three places changed into it's own helper/method? e.g.: thecall->msg->header.prog == client->msg.header.prog && thecall->msg->header.vers == client->msg.header.vers && thecall->msg->header.serial == client->msg.header.serial && thecall->expectReply and then the follow-up patch to add the additional '.type' checks?

> + call->msg->header.prog == client->msg.header.prog && > call->msg->header.vers == client->msg.header.vers && > call->msg->header.serial == client->msg.header.serial && > call->expectReply) > @@ -1207,7 +1208,8 @@ static int virNetClientCallDispatchStream(virNetClientPtr client) > > /* Find oldest dummy message waiting for incoming data. */ > for (thecall = client->waitDispatch; thecall; thecall = thecall->next) { > - if (thecall->msg->header.prog == client->msg.header.prog && > + if (thecall->msg->header.type == VIR_NET_STREAM && > + thecall->msg->header.prog == client->msg.header.prog && > thecall->msg->header.vers == client->msg.header.vers && > thecall->msg->header.serial == client->msg.header.serial && > thecall->expectReply && > @@ -1225,7 +1227,8 @@ static int virNetClientCallDispatchStream(virNetClientPtr client) > case VIR_NET_OK: > /* Find oldest abort/finish message. */ > for (thecall = client->waitDispatch; thecall; thecall = thecall->next) { > - if (thecall->msg->header.prog == client->msg.header.prog && > + if (thecall->msg->header.type == VIR_NET_STREAM && > + thecall->msg->header.prog == client->msg.header.prog && > thecall->msg->header.vers == client->msg.header.vers && > thecall->msg->header.serial == client->msg.header.serial && > thecall->expectReply && >