diff options
| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2011-09-13 15:09:40 +0200 |
|---|---|---|
| committer | Clark Williams <williams@redhat.com> | 2011-11-14 11:02:09 -0600 |
| commit | 6dc3044a505e54e23412b7cb779a27717e9b969a (patch) | |
| tree | 769216c9642bf166d3f723a525f4a5e9ee79e331 /drivers | |
| parent | d21015cd63d15534f50c5ad62d2a873020947b65 (diff) | |
ipc/sem: Rework semaphore wakeups
Current sysv sems have a weird ass wakeup scheme that involves keeping
preemption disabled over a potential O(n^2) loop and busy waiting on
that on other CPUs.
Kill this and simply wake the task directly from under the sem_lock.
This was discovered by a migrate_disable() debug feature that
disallows:
spin_lock();
preempt_disable();
spin_unlock()
preempt_enable();
Cc: Manfred Spraul <manfred@colorfullife.com>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Manfred Spraul <manfred@colorfullife.com>
Link: http://lkml.kernel.org/r/1315994224.5040.1.camel@twins
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'drivers')
0 files changed, 0 insertions, 0 deletions