[OpenSIPS-Users] ERROR:core:io_watch_del: BUG - trying to del fd 38 with flags 2 1

[Gupta, Rahul]

Hi Bogdan,

Almost a month ago, I have raised the issue regarding the opensips log file filling up with the following message

ERROR:core:io_watch_del: BUG - trying to del fd 38 with flags 2 1

Now I can reproduce it every time with the following scenario:


1)      UAC and UAS are connected to opensips proxy with TCP transport

2)      Connections looks good

3)      Netstat shows the connection to UAC in ESTABLISHED state and the tcp_conn_lists of opensips also looks fine for that UAC

4)      Now unplug the Ethernet cable on UAC

5)      After tcp connection timeout (set to 5 mins in opensips.cfg), the tcp connection goes away from netstat as well as from tcp_conn_lists

6)      UAS tries another tcp call to the UAC which is still unplugged

7)      tcp_conn_lists shows the tcp connection to the UAC and netstat shows the connection in SYN_SENT state

8)      After the tcp connection timeout (set to 5 mins in opensips.cfg), the connection goes away from netstat however it remains there in tcp_conn_lists and at that moment the "BUG - trying to del fd 38 with flags 2 1" starts printing in infinite loop.


I looked at the source code and observed the following


1)      When the network cable is plugged in

The io_watch_add happens with flag IO_WATCH_READ in tcp_main.c  when the command is CONN_NEW

2)      When the network cable is unplugged

The io_watch_add happens with flag IO_WATCH_WRITE in tcp_main.c  when the command is ASYNC_CONNECT


3)      While doing io_watch_del after timeout, from handle_tcpconn_ev method, io_watch_del always uses IO_WATCH_READ to delete the fd, which gives this error in case of unplugged cable.

Please look into this and suggest how can I fix this issue ?

Thanks
Rahul Gupta






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