[Bug 1584393] Re: systemctl restart networking hangs reloading ssh.service

[Martin Pitt]

I still cannot reproduce this. In a xenial cloud instance I ran

   for i in `seq 50`; do systemctl reset-failed networking; systemctl restart networking; 
done

successfully, this is with a standard /etc/network/interfaces.d/50
-cloud-init.cfg with just "auto ens3" and "iface ens3 inet dhcp" and no
other interface (besides lo).

We can fix this case more centrally in invoke-rc.d though; this is only
safe for "reload" and "force-reload", but that will cover this
networking/openssh deadlock.

If you can reproduce this, please apply this patch to invoke-rc.d:

   sudo patch /usr/sbin/invoke-rc.d /tmp/invoke-rc.d.patch

and confirm that this fixes it. Thanks!

** Patch added: "invoke-rc.d patch"
   https://bugs.launchpad.net/ubuntu/+source/openssh/+bug/1584393/+attachment/4700609/+files/invoke-rc.d.patch

** Changed in: openssh (Ubuntu)
     Assignee: (unassigned) => Martin Pitt (pitti)

** Changed in: openssh (Ubuntu)
       Status: Triaged => Incomplete

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https://bugs.launchpad.net/bugs/1584393

Title:
  systemctl restart networking hangs reloading ssh.service

Status in openssh package in Ubuntu:
  Incomplete

Bug description:
  Issues "systemctl restart networking" never exits. It hangs during a
  call to "systemctl reload ssh.service":

  ● networking.service - Raise network interfaces
     Loaded: loaded (/lib/systemd/system/networking.service; enabled; vendor preset: enabled)
    Drop-In: /run/systemd/generator/networking.service.d
             └─50-insserv.conf-$network.conf
     Active: activating (start) since Sat 2016-05-21 21:41:58 UTC; 18s ago
       Docs: man:interfaces(5)
    Process: 1288 ExecStop=/sbin/ifdown -a --read-environment (code=exited, status=0/SUCCESS)
    Process: 1376 ExecStartPre=/bin/sh -c [ "$CONFIGURE_INTERFACES" != "no" ] && [ -n "$(ifquery --read-environment --list --exclude=lo)" ] &
   Main PID: 1383 (ifup)
      Tasks: 7 (limit: 512)
     Memory: 1.8M
        CPU: 111ms
     CGroup: /system.slice/networking.service
             ├─1383 /sbin/ifup -a --read-environment
             ├─1479 /sbin/dhclient -1 -v -pf /run/dhclient.enp0s3.pid -lf /var/lib/dhcp/dhclient.enp0s3.leases -I -df /var/lib/dhcp/dhclient6
             ├─1480 /bin/sh -c /bin/run-parts --exit-on-error /etc/network/if-up.d
             ├─1481 /bin/run-parts --exit-on-error /etc/network/if-up.d
             ├─1504 /bin/sh /etc/network/if-up.d/openssh-server
             ├─1507 /bin/sh /usr/sbin/invoke-rc.d ssh reload
             └─1527 systemctl reload ssh.service

  Then issuing the same command from another terminal causes the first
  to exit successfully (the second also exists successfully).

  On the official vagrant image, I get this problem independently of
  whether the command is issued through and ssh session. I've gotten the
  same behavior on the official xenial AMIs.

  ProblemType: Bug
  DistroRelease: Ubuntu 16.04
  Package: ifupdown 0.8.10ubuntu1
  ProcVersionSignature: Ubuntu 4.4.0-22.40-generic 4.4.8
  Uname: Linux 4.4.0-22-generic x86_64
  ApportVersion: 2.20.1-0ubuntu2
  Architecture: amd64
  Date: Sat May 21 21:35:08 2016
  ProcEnviron:
   TERM=xterm
   PATH=(custom, no user)
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  SourcePackage: ifupdown
  UpgradeStatus: No upgrade log present (probably fresh install)

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