misc/56206: if_lagg tests leave rump_server processes running

[gson%gson.org@localhost (Andreas Gustafsson)]

>Number:         56206
>Category:       misc
>Synopsis:       if_lagg tests leave rump_server processes running
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    misc-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon May 24 19:35:00 +0000 2021
>Originator:     Andreas Gustafsson
>Release:        NetBSD-current, source date >= 2021.05.17.06.31.30
>Organization:
>Environment:
System: NetBSD
Architecture: i386
Machine: i386
>Description:

Since if_lagg and its tests were added on May 17, running the ATF
tests leaves two rump_server processes running every time:

  UID   PID PPID   CPU PRI NI    VSZ   RSS WCHAN   STAT TTY      TIME COMMAND
    0 14946    1  1548  85  0 103028  1524 psem    Ssl  ?     0:02.71 rump_server -lrumpnet -lrumpnet_net -lrumpnet_netinet -lrumpnet_shmif -lrumpnet_lagg -lrumpnet_netinet6 unix://commsock1 
    0 27681    1  1585  85  0 106908  1556 psem    Isl  ?     0:02.81 rump_server -lrumpnet -lrumpnet_net -lrumpnet_netinet -lrumpnet_shmif -lrumpnet_lagg -lrumpnet_netinet6 unix://commsock0 

The above ps output was extracted from:

  http://releng.netbsd.org/b5reports/i386/2021/2021.05.17.06.31.30/test.log

(near the end, search for "ps-post-test")

>How-To-Repeat:

Run the ATF tests, then ps -glaxww.

>Fix: