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SubjectRe: [PATCH] locking/rtmutex: remove unused cmpxchg_relaxed
Davidlohr Bueso <> writes:
> On Tue, 21 Jan 2020, Alex Shi wrote:

Subject: locking/rtmutex: remove unused cmpxchg_relaxed

should be

Subject: locking/rtmutex: Remove unused rt_mutex_cmpxchg_relaxed()

You're not removing cmpxchg_relaxed, right?

>> No one use this macro after it was introduced. Better to remove it?

Please make that factual.

The macro was never used at all. Remove it.

> You also need to remove it for the CONFIG_DEBUG_RT_MUTEXES=y case.


> Hmm unrelated, but do we want CCAS for rtmutex fastpath? Ie:
> (l->owner == c && cmpxchg_acquire(&l->owner, c, n) == c)
> That would optimize for the contended case and avoid the cmpxchg - it would
> also help if we ever do the top-waiter spin thing.

Not sure if it buys much, but it kinda makes sense.



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