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  1. 25 9月, 2018 2 次提交
    • M
      lxc_monitor: Avoid AB / BA lock race · 7882c6ec
      由 Mark Asselstine 提交于 
      A deadlock situation can occur when autostarting a LXC domain 'guest'
due to two threads attempting to take opposing locks while holding
opposing locks (AB BA problem). Thread A takes and holds the 'vm' lock
while attempting to take the 'client' lock, meanwhile, thread B takes
and holds the 'client' lock while attempting to take the 'vm' lock.

The potential for this can be seen as follows:

Thread A:
virLXCProcessAutostartDomain (takes vm lock)
 --> virLXCProcessStart
  --> virLXCProcessConnectMonitor
   --> virLXCMonitorNew
    --> virNetClientSetCloseCallback (wants client lock)

Thread B:
virNetClientIncomingEvent (takes client lock)
 --> virNetClientIOHandleInput
  --> virNetClientCallDispatch
   --> virNetClientCallDispatchMessage
    --> virNetClientProgramDispatch
     --> virLXCMonitorHandleEventInit
      --> virLXCProcessMonitorInitNotify (wants vm lock)

Since these threads are scheduled independently and are preemptible it
is possible for the deadlock scenario to occur where each thread locks
their first lock but both will fail to get their second lock and just
spin forever. You get something like:

virLXCProcessAutostartDomain (takes vm lock)
 --> virLXCProcessStart
  --> virLXCProcessConnectMonitor
   --> virLXCMonitorNew
<...>
virNetClientIncomingEvent (takes client lock)
 --> virNetClientIOHandleInput
  --> virNetClientCallDispatch
   --> virNetClientCallDispatchMessage
    --> virNetClientProgramDispatch
     --> virLXCMonitorHandleEventInit
      --> virLXCProcessMonitorInitNotify (wants vm lock but spins)
<...>
    --> virNetClientSetCloseCallback (wants client lock but spins)

Neither thread ever gets the lock it needs to be able to continue
while holding the lock that the other thread needs.

The actual window for preemption which can cause this deadlock is
rather small, between the calls to virNetClientProgramNew() and
execution of virNetClientSetCloseCallback(), both in
virLXCMonitorNew(). But it can be seen in real world use that this
small window is enough.

By moving the call to virNetClientSetCloseCallback() ahead of
virNetClientProgramNew() we can close any possible chance of the
deadlock taking place. There should be no other implications to the
move since the close callback (in the unlikely event was called) will
spin on the vm lock. The remaining work that takes place between the
old call location of virNetClientSetCloseCallback() and the new
location is unaffected by the move.
Signed-off-by: NMark Asselstine <mark.asselstine@windriver.com>
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
      7882c6ec
    • P
      vircgroup: rename virCgroupAdd.*Task to virCgroupAdd.*Process · 0772c346
      由 Pavel Hrdina 提交于 
      In cgroup v2 we need to handle processes and threads differently,
following patch will introduce virCgroupAddThread.
Reviewed-by: NFabiano Fidêncio <fidencio@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>
Signed-off-by: NPavel Hrdina <phrdina@redhat.com>
      0772c346
  3. 24 9月, 2018 2 次提交
  5. 20 9月, 2018 2 次提交
  7. 18 9月, 2018 1 次提交
    • M
      security_manager: Load lock plugin on init · 3e26b476
      由 Michal Privoznik 提交于 
      Now that we know what metadata lock manager user wishes to use we
can load it when initializing security driver. This is achieved
by adding new argument to virSecurityManagerNewDriver() and
subsequently to all functions that end up calling it.

The cfg.mk change is needed in order to allow lock_manager.h
inclusion in security driver without 'syntax-check' complaining.
This is safe thing to do as locking APIs will always exist (it's
only backend implementation that changes). However, instead of
allowing the include for all other drivers (like cpu, network,
and so on) allow it only for security driver. This will still
trigger the error if including from other drivers.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>
      3e26b476
  9. 13 8月, 2018 1 次提交
  11. 30 7月, 2018 1 次提交
  13. 27 7月, 2018 4 次提交
  15. 26 7月, 2018 5 次提交
  17. 23 7月, 2018 1 次提交
    • A
      src: Make virStr*cpy*() functions return an int · 6c0d0210
      由 Andrea Bolognani 提交于 
      Currently, the functions return a pointer to the
destination buffer on success or NULL on failure.

Not only does this kind of error handling look quite
alien in the context of libvirt, where most functions
return zero on success and a negative int on failure,
but it's also somewhat pointless because unless there's
been a failure the returned pointer will be the same
one passed in by the user, thus offering no additional
value.

Change the functions so that they return an int
instead.
Signed-off-by: NAndrea Bolognani <abologna@redhat.com>
      6c0d0210
  19. 03 7月, 2018 3 次提交
  21. 27 6月, 2018 4 次提交
  23. 12 6月, 2018 1 次提交
  25. 06 6月, 2018 1 次提交
  27. 05 6月, 2018 1 次提交
  29. 14 5月, 2018 1 次提交
  31. 04 5月, 2018 4 次提交
  33. 23 4月, 2018 2 次提交
  35. 18 4月, 2018 1 次提交
    • M
      virobject: Introduce VIR_CLASS_NEW() macro · 10f94828
      由 Michal Privoznik 提交于 
      So far we are repeating the following lines over and over:

  if (!(virSomeObjectClass = virClassNew(virClassForObject(),
                             "virSomeObject",
                             sizeof(virSomeObject),
                             virSomeObjectDispose)))
      return -1;

While this works, it is impossible to do some checking. Firstly,
the class name (the 2nd argument) doesn't match the name in the
code in all cases (the 3rd argument). Secondly, the current style
is needlessly verbose. This commit turns example into following:

  if (!(VIR_CLASS_NEW(virSomeObject,
                      virClassForObject)))
      return -1;
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>
      10f94828
  37. 17 4月, 2018 1 次提交
  39. 12 4月, 2018 2 次提交