[Bug 1819728] [NEW] Please backport "fix race between daemon-reload and other commands #8803" to 16.04 (for UC16)

[Michael Vogt]

Public bug reported:

On Ubuntu Core we recently hit the a race in daemon-reload and systemctl
twice. This race is fixed in systemd upstream: "fix race between daemon-
reload and other commands #8803".

To reproduce its enough to run:

for i in $(seq 50); do
  systemctl daemon-reload &
  systemctl start ssh &
done

This will result in "systemctl start ssh" hanging in ppoll. With the
patch applied the hangs go away.

** Affects: systemd (Ubuntu)
     Importance: Undecided
         Status: New

** Affects: systemd (Ubuntu Xenial)
     Importance: Undecided
         Status: New

** Affects: systemd (Ubuntu Bionic)
     Importance: Undecided
         Status: New

** Patch added: "debdiff with a port of the fix in PR#8803"
   https://bugs.launchpad.net/bugs/1819728/+attachment/5245665/+files/fix-systemctl-race-8803.debdiff

** Summary changed:

- Please backport " fix race between daemon-reload and other commands #8803 "
+ Please backport "fix race between daemon-reload and other commands #8803" to 16.04 (for UC16)

** Also affects: systemd (Ubuntu Bionic)
   Importance: Undecided
       Status: New

** Also affects: systemd (Ubuntu Xenial)
   Importance: Undecided
       Status: New

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https://bugs.launchpad.net/bugs/1819728

Title:
  Please backport "fix race between daemon-reload and other commands
  #8803" to 16.04 (for UC16)

Status in systemd package in Ubuntu:
  New
Status in systemd source package in Xenial:
  New
Status in systemd source package in Bionic:
  New

Bug description:
  On Ubuntu Core we recently hit the a race in daemon-reload and
  systemctl twice. This race is fixed in systemd upstream: "fix race
  between daemon-reload and other commands #8803".

  To reproduce its enough to run:

  for i in $(seq 50); do
    systemctl daemon-reload &
    systemctl start ssh &
  done

  This will result in "systemctl start ssh" hanging in ppoll. With the
  patch applied the hangs go away.

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