[Qemu-devel] [RFC PATCH 0/3] Timer thread-safety improvements

[Paolo Bonzini <pbonzini@redhat.com>]

These four patches go on top of Stefan's patch introducing a lock for
a timerlist's active timers.  Patches 1 and 2 fix bugs and probably
should simply be squashed into his patch.

Patch 3 is an optimization and code simplification.  It could even go
in _before_ introducing the lock, at Stefan's discretion.

Patch 4 (incomplete and not even compiled) is an optimization that avoids
taking the lock if timerlist_run_timers does not have any timer ready to
fire.  I'm posting it just to share the idea and will resend it with
more documentation later, once the RCU infrastructure is in.

Paolo Bonzini (4):
  qemu-timer: do del+mod atomically
  qemu-timer: fix race conditions on freeing the timer
  qemu-timer: do not take the lock in timer_pending
  qemu-timer: use RCU to preserve the timers during lockless lookup

 qemu-timer.c | 96 +++++++++++++++++++++++++++++++++++++++---------------------
 1 file changed, 62 insertions(+), 34 deletions(-)

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1.8.3.1