** Description changed:

+ [SRU Notes]
+ 
+ [rbasak] Requires apt 1.2.28 (Xenial) and 1.6.5 (Bionic), both of which
+ are currently in proposed. Do not release to updates without releasing
+ the newer apt first.
+ 
  [Impact]
  PackageKit needs an adjustment for frontend locking, so it does not release 
the frontend lock during dpkg invocations, but only the normal dpkg lock.
  
  Frontend locking prevents race conditions between multiple dpkg
  frontends, which can cause other frontends to be interrupted while they
  are installing stuff - the frontend loses the dpkg lock between dpkg
  runs and the system ends up in a partially configured state.
  
  See bug 1781169 for more details on frontend locking.
  
  [Test case]
  1. Install a package
  2. Modify prerm to sleep
  3. Remove package via pkcon and check that packagekitd process holds 
lock-frontend and dpkg holds lock (we release lock by closing the lock files, 
so just check if the files are open).
  
  [Regression potential]
  Changing the code to call UnLockInner() vs UnLock() makes it do less steps 
and only release "lock" as before, and not "lock-frontend". That should not be 
causing any regressions.
  
  The patch also adds a call to LockInner() after the dpkg execution to
  make it reacquire "lock", this could fail. It should not have much
  impact however, as it only affects a single transaction AFAICT. It does
  reduce the risk of some frontend not implementing frontend locking from
  racing while we still hold the frontend lock, though.
  
  [Other info]
  This is part of a wider series of SRUs for frontend locking
  
  - dpkg (bug 1796081)
  - apt (bug 1781169)
  - python-apt (bug 1795407)
  - packagekit (bug 1795614)
  - unattended-upgrades (bug 1789637)
  - aptdaemon (no bug filed yet)
  
  Further details about frontend locking can be found in
  https://lists.debian.org/debian-dpkg/2017/01/msg00044.html

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https://bugs.launchpad.net/bugs/1795614

Title:
  packagekit frontend locking

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