wengzuyang:

1. Software versions
   Chaos Calmer

2. there is two ways to reproduce:
   a).type commond "/etc/init.d/network restart" when device power on and starting network.(small chance to reproduce in this way)
   b). type commond "/etc/init.d/network restart;/etc/init.d/network restart".(always reproduce in this way)

3. I fllowed codes and find the reason:
   netifd can not be terminate by "ubus call service delete '{"name":"network"}'"
   there are multiple netifd processing:

   5962 ? S 0:02 [kworker/0:0]
   7576 ttymxc0 Ss 0:00 -ash
   8708 ? S 0:00 /sbin/netifd
   8723 ? S 0:00 [kworker/0:1]
   8965 ? S 0:00 /sbin/netifd
   9011 ? S 0:00 /sbin/netifd
   9054 ? S 0:00 /sbin/netifd
   9125 ? S 0:00 /sbin/netifd
   9212 ? S 0:00 /sbin/netifd
   9317 ? S 0:00 /sbin/netifd
   9392 ? S 0:00 /sbin/netifd

   the reason of netifd can not be killed is:
   netifd reseived TERM signal and run uloop_end() before uloop_run()
   so uloop_cancelled(in libubox) is reset to false when uloop_run()

4. my solution:
   delete the line:
   uloop_cancelled = false; --> in void uloop_run(void) --> in uloop.c --> in libubox-2015-11-08(new version libubox have this line too)
   uloop_cancelled is already init by "bool uloop_cancelled = false;",it is no need reset to false by uloop_run() again.