* Oleg Nesterov <[email protected]> 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.
Ingo
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