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Date: Thu, 4 May 2017 15:39:49 +0800
From: Fam Zheng <famz@redhat.com>
Message-ID: <20170504073949.GA4725@lemon.lan>
References: <20170420120058.28404-1-pbonzini@redhat.com>
	<20170420120058.28404-14-pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 13/17] coroutine-lock: introduce
 qemu_co_mutex_lock_unlock
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org

On Thu, 04/20 14:00, Paolo Bonzini wrote:
> +    if (atomic_cmpxchg(&mutex->locked, waiters, waiters + 1) != waiters) {

Is it still useful to try the fast path again if there are now even more
waiters, i.e.  "atomic_cmpxchg(...) > waiters"?

> +        goto retry_fast_path;
> +    }
> +
> +    qemu_co_mutex_lock_slowpath(ctx, mutex);
> +    qemu_co_mutex_unlock(mutex);
> +}
> +
>  void coroutine_fn qemu_co_mutex_unlock(CoMutex *mutex)
>  {
>      Coroutine *self = qemu_coroutine_self();
> -- 
> 2.9.3
> 
> 
>