Hi, After merge this patch and update the test environment, the issue still persists.
Let me clear my client app config: 1. register a reset callback, which will call vnet_disconnect there and also trigger reconnect by send event to the ctrl process.) 2. register a connected callback, which will handle connect err by trigger reconnect, on success, it will record session handle and extract tcp sequence for our app usage. 3. register a disconnect callback, which basically do same as reset callback. 4. register a cleanup callback and accept callback, which basically make the session layer happy without actually relevant work to do. There is a ctrl process in mater, which will handle periodically reconnect or triggered by event. BTW, I also see frequently warning 'session %u hash delete rv -3' in session_delete in my environment, hope this helps to investigate. Florin Coras <fcoras.li...@gmail.com> 于2023年3月20日周一 23:29写道： > Hi, > > Understood and yes, connect will synchronously fail if port is not > available, so you should be able to retry it later. > > Regards, > Florin > > On Mar 20, 2023, at 1:58 AM, Zhang Dongya <fortitude.zh...@gmail.com> > wrote: > > Hi, > > It seems the issue occurs when there are disconnect called because our > network can't guarantee a tcp can't be reset even when 3 ways handshake is > completed (firewall issue :( ). > > When we find the app layer timeout, we will first disconnect (because we > record the session handle, this session might be a half open session), does > vnet session layer guarantee that if we reconnect from master thread when > the half open session still not be released yet (due to asynchronous logic) > that the reconnect fail? if then we can retry connect later. > > I prefer to not registered half open callback because I think it make app > complicated from a TCP programming prospective. > > For your patch, I think it should be work because I can't delete the half > open session immediately because there is worker configured, so the half > open will be removed from bihash when syn retrans timeout. I have merged > the patch and will provide feedback later. > > Florin Coras <fcoras.li...@gmail.com> 于2023年3月20日周一 13:09写道： > >> Hi, >> >> Inline. >> >> On Mar 19, 2023, at 6:47 PM, Zhang Dongya <fortitude.zh...@gmail.com> >> wrote: >> >> Hi, >> >> It can be aborted both in established state or half open state because I >> will do timeout in our app layer. >> >> >> [fc] Okay! Is the issue present irrespective of the state of the session >> or does it happen only after a disconnect in hanf-open state? More lower. >> >> >> Regarding your question, >> >> - Yes we add a builtin in app relys on C apis that mainly use >> vnet_connect/disconnect to connect or disconnect session. >> >> >> [fc] Understood >> >> - We call these api in a vpp ctrl process which should be running on the >> master thread, we never do session setup/teardown on worker thread. (the >> environment that found this issue is configured with 1 master + 1 worker >> setup.) >> >> >> [fc] With vpp latest it’s possible to connect from first workers. It’s an >> optimization meant to avoid 1) worker barrier on syns and 2) entering poll >> mode on main (consume less cpu) >> >> - We started to develop the app using 22.06 and I keep to merge upstream >> changes to latest vpp by cherry-picking. The reason for line mismatch is >> that I added some comment to the session layer code, it should be equal to >> the master branch now. >> >> >> [fc] Ack >> >> >> When reading the code I understand that we mainly want to cleanup half >> open from bihash in session_stream_connect_notify, however, in syn-sent >> state if I choose to close the session, the session might be closed by my >> app due to session setup timeout (in second scale), in that case, session >> will be marked as half_open_done and half open session will be freed >> shortly in the ctrl thread (the 1st worker?). >> >> >> [fc] Actually, this might be the issue. We did start to provide a >> half-open session handle to apps which if closed does clean up the session >> but apparently it is missing the cleanup of the session lookup table. Could >> you try this patch [1]? It might need additional work. >> >> Having said that, forcing a close/cleanup will not free the port >> synchronously. So, if you’re using fixed ports, you’ll have to wait for the >> half-open cleanup notification. >> >> >> Should I also registered half open callback or there are some other >> reason that lead to this failure? >> >> >> [fc] Yes, see above. >> >> Regards, >> Florin >> >> [1] https://gerrit.fd.io/r/c/vpp/+/38526 >> >> >> Florin Coras <fcoras.li...@gmail.com> 于2023年3月20日周一 06:22写道： >> >>> Hi, >>> >>> When you abort the connection, is it fully established or half-open? >>> Half-opens are cleaned up by the owner thread after a timeout, but the >>> 5-tuple should be assigned to the fully established session by that point. >>> tcp_half_open_connection_cleanup does not cleanup the bihash instead >>> session_stream_connect_notify does once tcp connect returns either success >>> or failure. >>> >>> So a few questions: >>> - is it accurate to assume you have a builtin vpp app and rely only on C >>> apis to interact with host stack? >>> - on what thread (main or first worker) do you call vnet_connect? >>> - what api do you use to close the session? >>> - what version of vpp is this because lines don’t match vpp latest? >>> >>> Regards, >>> Florin >>> >>> > On Mar 19, 2023, at 2:08 AM, Zhang Dongya <fortitude.zh...@gmail.com> >>> wrote: >>> > >>> > Hi list, >>> > >>> > recently in our application, we constantly triggered such abrt issue >>> which make our connectivity interrupt for a while: >>> > >>> > Mar 19 16:11:26 ubuntu vnet[2565933]: received signal SIGABRT, PC >>> 0x7fefd3b2000b >>> > Mar 19 16:11:26 ubuntu vnet[2565933]: >>> /home/fortitude/glx/vpp/src/vnet/tcp/tcp_input.c:3004 (tcp46_input_inline) >>> assertion `tcp_lookup_is_valid (tc0, b[0], tcp_buffer_hdr (b[0]))' fails >>> > >>> > Our scenario is quite simple, we will make 4 parallel tcp connection >>> (use 4 fixed source ports) to a remote vpp stack (fixed ip and port), and >>> will do some keepalive in our application layer, since we only use the vpp >>> tcp stack to make the middle box happy with the connection, we do not use >>> the data transport of tcp statck actually. >>> > >>> > However, since the network condition is complex, we have to always >>> need to abrt the connection and reconnect. >>> > >>> > I keep to merge upstream session and tcp fix however the issue still >>> not fixed, what I found now it may be in some case >>> tcp_half_open_connection_cleanup may not deleted the half open session from >>> the lookup table (bihash) and the session index is realloced by other >>> connection. >>> > >>> > Hope the list can provide some hint about how to overcome this issue, >>> thanks a lot. >>> > >>> > >>> > >>> >>> >>> >>> >>> >> >> >> >> >> > > > > >
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