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| author | Peter Zijlstra <peterz@infradead.org> | 2011-09-14 09:57:04 (GMT) |
|---|---|---|
| committer | Scott Wood <scottwood@freescale.com> | 2014-04-10 00:19:55 (GMT) |
| commit | 27659d80405cf939d803186eae2d91f286cc75d2 (patch) | |
| tree | 89ba8ee59b88dbea9468f7b0a1dc20fcd5d5cbdb /ipc/namespace.c | |
| parent | 7e0509fe7647c827b37ee4034b80c3d8b399830c (diff) | |
| download | linux-fsl-qoriq-27659d80405cf939d803186eae2d91f286cc75d2.tar.xz | |
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 'ipc/namespace.c')
0 files changed, 0 insertions, 0 deletions