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

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

The following reply was made to PR bin/57952; it has been noted by GNATS.

From: Taylor R Campbell <riastradh%NetBSD.org@localhost>
To: Roy Marples <roy%marples.name@localhost>
Cc: gnats-bugs%NetBSD.org@localhost,
	Martin Husemann <martin%duskware.de@localhost>,
	gnats-admin%NetBSD.org@localhost,
	netbsd-bugs%NetBSD.org@localhost
Subject: Re: bin/57952 (dhcpcd(8) inexplicably terminated in the night)
Date: Fri, 23 Feb 2024 23:29:05 +0000

 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]=20
  2702 ?     S      0:00.12 | |-- dhcpcd: [privileged proxy]=20
  9448 ?     S      0:00.01 | |-- dhcpcd: [control proxy]=20
 16699 ?     S      0:00.01 | `-- dhcpcd: [network proxy]=20
 
 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 =3D unlimited
 proc.29577.rlimit.coredumpsize.hard =3D unlimited
 proc.2702.rlimit.coredumpsize.soft =3D unlimited
 proc.2702.rlimit.coredumpsize.hard =3D unlimited
 proc.9448.rlimit.coredumpsize.soft =3D unlimited
 proc.9448.rlimit.coredumpsize.hard =3D unlimited
 proc.16699.rlimit.coredumpsize.soft =3D unlimited
 proc.16699.rlimit.coredumpsize.hard =3D 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_rec=
 v: read: Undefined error: 0
   <daemon.err>Feb 23 23:15:49 nanocons dhcpcd[privileged proxy]: ps_root_re=
 cvmsg: 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_dod=
 ispatch: Connection reset by peer
   <daemon.err>Feb 23 23:19:25 nanocons dhcpcd[privileged proxy]: control_fr=
 ee: No such file or directory
   <daemon.err>Feb 23 23:19:25 nanocons dhcpcd[privileged proxy]: ps_sendpsm=
 msg: 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: Co=
 nnection 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: Destina=
 tion 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.