linux-kernel - Re: [RFC][PATCH 7/7] kref: Implement using refcount

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Message-ID: <20161117163624.GP22855@arm.com>
Date:   Thu, 17 Nov 2016 16:36:24 +0000
From:   Will Deacon <will.deacon@....com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Boqun Feng <boqun.feng@...il.com>, gregkh@...uxfoundation.org,
        keescook@...omium.org, elena.reshetova@...el.com, arnd@...db.de,
        tglx@...utronix.de, mingo@...nel.org, hpa@...or.com,
        dave@...gbits.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCH 7/7] kref: Implement using refcount_t

On Thu, Nov 17, 2016 at 05:11:10PM +0100, Peter Zijlstra wrote:
> On Thu, Nov 17, 2016 at 12:08:36PM +0000, Will Deacon wrote:
> > All sounds reasonable to me. It's worth pointing out that you can't create
> > order using a control dependency hanging off the status flag of a
> > store-conditional, but the code in question here has the dependency from
> > the loaded value, which is sufficient.
> 
> Yeah, I'm always surprised by that 'feature'. Is that ARM specific? Or
> so more LL/SC archs have this?

In general, I'm not sure, but I think PPC does allow for the control
dependency.

Will