Hi Florin, Thanks a lot, the previous patch and with reset disabled have been running 1 day without issue.
I will enable reset and with your new patch, will provide feedback later. Florin Coras <fcoras.li...@gmail.com> 于2023年3月22日周三 02:12写道： > 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> 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> >> 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> 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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