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Date: Wed, 18 May 2016 15:04:43 -0400
From: "Emilio G. Cota" <cota@braap.org>
Message-ID: <20160518190443.GA17967@flamenco>
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Subject: Re: [Qemu-devel] [PATCH v5 07/18] qemu-thread: add simple
 test-and-set spinlock
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To: Sergey Fedorov <serge.fdrv@gmail.com>
Cc: QEMU Developers <qemu-devel@nongnu.org>, MTTCG Devel <mttcg@listserver.greensocs.com>, Alex =?iso-8859-1?Q?Benn=E9e?= <alex.bennee@linaro.org>, Paolo Bonzini <pbonzini@redhat.com>, Peter Crosthwaite <crosthwaite.peter@gmail.com>, Richard Henderson <rth@twiddle.net>

On Wed, May 18, 2016 at 21:21:26 +0300, Sergey Fedorov wrote:
> On 14/05/16 06:34, Emilio G. Cota wrote:
> > +static inline int qemu_spin_trylock(QemuSpin *spin)
> > +{
> > +    if (atomic_test_and_set_acquire(&spin->value)) {
> > +        return -EBUSY;
> 
> Seems this should be:
> 
>     return EBUSY;

I don't think any caller would/should ever check this value, other
than if (!trylock).

It's true though that pthread_mutex_trylock returns EBUSY, so it's
probably best to remain consistent with it; I've made the change.

Thanks,

		Emilio