Messages in this thread | | | Date | Mon, 10 Feb 2014 18:38:33 +0100 | From | Peter Zijlstra <> | Subject | Re: allow preemption in check_task_state |
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On Mon, Feb 10, 2014 at 06:17:12PM +0100, Nicholas Mc Guire wrote: > maybe I'm missing/missunderstanding something here but > pi_unlock -> arch_spin_unlock is a full mb()
Nope, arch_spin_unlock() on x86 is a single add[wb] without LOCK prefix.
The lock and unlock primitives are in general specified to have ACQUIRE resp. RELEASE semantics.
See Documentation/memory-barriers.txt for far too much head-hurting details.
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