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    SubjectRe: [PATCH] locking/rtmutex: remove unused cmpxchg_relaxed
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    Davidlohr Bueso <dave@stgolabs.net> 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.

    Yes.

    > 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.

    Thanks,

    tglx

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