Re: bin/57952 (dhcpcd(8) inexplicably terminated in the night)

[Taylor R Campbell <riastradh%NetBSD.org@localhost>]

I tried getting a core dump by doing:

# chown _dhcpcd:_dhcpcd /var/chroot/dhcpcd

and then sending SIGABRT to each of the dhcpcd processes.

Here's a sample of the process hierarchy from `ps -Adww':

29577 ?     S      0:00.11 |-- dhcpcd: [manager] [ip4] [ip6] 
 2702 ?     S      0:00.12 | |-- dhcpcd: [privileged proxy] 
 9448 ?     S      0:00.01 | |-- dhcpcd: [control proxy] 
16699 ?     S      0:00.01 | `-- dhcpcd: [network proxy] 

I verified with sysctl proc.$pid.rlimit.coredumpsize.soft/hard that
the core dump size rlimit is unlimited:

# for pid in 29577 2702 9448 16699; do for x in soft hard; do sysctl proc.$pid.rlimit.coredumpsize.$x; done; done
proc.29577.rlimit.coredumpsize.soft = unlimited
proc.29577.rlimit.coredumpsize.hard = unlimited
proc.2702.rlimit.coredumpsize.soft = unlimited
proc.2702.rlimit.coredumpsize.hard = unlimited
proc.9448.rlimit.coredumpsize.soft = unlimited
proc.9448.rlimit.coredumpsize.hard = unlimited
proc.16699.rlimit.coredumpsize.soft = unlimited
proc.16699.rlimit.coredumpsize.hard = unlimited

Results (pids replaced by roles in the log messages because I restart
dhcpcd each time, of course):

- kill -ABRT manager (cwd /var/chroot/dhcpcd): no core in / or in
  /var/chroot/dhcpcd, log messages from privileged proxy:

  <daemon.err>Feb 23 23:15:49 nanocons dhcpcd[privileged proxy]: ps_ctl_recv: read: Undefined error: 0
  <daemon.err>Feb 23 23:15:49 nanocons dhcpcd[privileged proxy]: ps_root_recvmsg: Connection reset by peer

  (This `Undefined error: 0' seems like a bug in itself -- something
  lost errno, perhaps?)

- kill -ABRT privileged proxy (cwd /): core dumped in /, no log
  messages

- kill -ABRT control proxy (cwd /var/chroot/dhcpcd): no core in / or
  in /var/chroot/dhcpcd, log messages from privileged proxy:

  <daemon.err>Feb 23 23:19:25 nanocons dhcpcd[privileged proxy]: ps_ctl_dodispatch: Connection reset by peer
  <daemon.err>Feb 23 23:19:25 nanocons dhcpcd[privileged proxy]: control_free: No such file or directory
  <daemon.err>Feb 23 23:19:25 nanocons dhcpcd[privileged proxy]: ps_sendpsmmsg: Destination address required
  <daemon.err>Feb 23 23:19:25 nanocons dhcpcd[privileged proxy]: ps_dostop: Destination address required

- kill -ABRT network proxy (cwd /var/chroot/dhcpcd): no core in / or
  in /var/chroot/dhcpcd, log messages from privileged proxy:

  <daemon.err>Feb 23 23:21:35 nanocons dhcpcd[5931]: ps_inet_dodispatch: Connection reset by peer
  <daemon.err>Feb 23 23:21:35 nanocons dhcpcd[5931]: control_free: No such file or directory
  <daemon.err>Feb 23 23:21:35 nanocons dhcpcd[5931]: ps_sendpsmmsg: Destination address required
  <daemon.err>Feb 23 23:21:35 nanocons dhcpcd[5931]: ps_dostop: Destination address required

So I infer that the network proxy must have crashed, in my original
case.  But I don't see how to trigger a core dump.