Messages in this thread | | | Date | Wed, 21 Dec 2005 19:26:22 +0100 | From | Ingo Molnar <> | Subject | Re: [patch 05/15] Generic Mutex Subsystem, mutex-core.patch |
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* Oleg Nesterov <oleg@tv-sign.ru> wrote:
> But why we can't add the waiter to ->wait_list _after_ xchg() ? What > makes the difference? Fastpath atomic op can happen before or after > xchg(), this is ok. Unlock path will look at ->wait_list only after > taking spinlock, at this time we already added this waiter to the > ->wait_list. > > In other words: we are holding ->wait_lock, nobody can even look at > ->wait_list. We can add the waiter to ->wait_list before or after > atomic_xchg() - it does not matter.
hm, you are right - i've added this optimization.
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