Hi, Okay, resetting of half-opens definitely not supported. I updated the patch to just clean them up on forced reset, without sending a reset to make sure session lookup table cleanup still happens.
Regards, Florin > On Mar 20, 2023, at 9:13 PM, Zhang Dongya <fortitude.zh...@gmail.com> wrote: > > Hi, > > After review my code, I found that I have add a flag to the vnet_disconnect > API which will call session_reset instead of session_close, the reason I do > this is to make intermediate firewall just flush the state and reconstruct if > I later reconnect. > > It seems in session_reset logic, for half open session, it also missing to > remove the session from the lookup hash which may cause the issue too. > > I change my code and will test with your patch along, will provide feedback > later. > > I also noticed the bihash issue discussed in the list recently, I will merge > later. > > Florin Coras <fcoras.li...@gmail.com <mailto:fcoras.li...@gmail.com>> > 于2023年3月21日周二 11:56写道： >> Hi, >> >> That last thing is pretty interesting. It’s either the issue fixed by this >> patch [1] or sessions are somehow cleaned up multiple times. If it’s the >> latter, I’d really like to understand how that happens. >> >> Regards, >> Florin >> >> [1] https://gerrit.fd.io/r/c/vpp/+/38507 >> >>> On Mar 20, 2023, at 6:52 PM, Zhang Dongya <fortitude.zh...@gmail.com >>> <mailto:fortitude.zh...@gmail.com>> wrote: >>> >>> 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 <mailto: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 >>>>> <mailto: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 <mailto: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 >>>>>>> <mailto: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 <mailto: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 >>>>>>>> > <mailto: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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