diff options
author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2011-09-13 15:09:40 +0200 |
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committer | Clark Williams <williams@redhat.com> | 2012-04-04 09:14:57 -0500 |
commit | 7c272a611ebb5c8cffe6b49cf18e4c5c6bd8d7a7 (patch) | |
tree | 37f88849120e9592c8fdb09029c94b21cf71c615 /include/linux/sysrq.h | |
parent | c2169355ac9f6e0052e0a1a94d33ff575ab9b05b (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 'include/linux/sysrq.h')
0 files changed, 0 insertions, 0 deletions