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

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Message-ID: <20161118105206.GM3117@twins.programming.kicks-ass.net>
Date:   Fri, 18 Nov 2016 11:52:06 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     "Reshetova, Elena" <elena.reshetova@...el.com>
Cc:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "keescook@...omium.org" <keescook@...omium.org>,
        "will.deacon@....com" <will.deacon@....com>,
        "arnd@...db.de" <arnd@...db.de>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...nel.org" <mingo@...nel.org>,
        "hpa@...or.com" <hpa@...or.com>,
        "dave@...gbits.org" <dave@...gbits.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC][PATCH 7/7] kref: Implement using refcount_t


Could you please fix you mailer to not unwrap the emails?

On Fri, Nov 18, 2016 at 10:47:40AM +0000, Reshetova, Elena wrote:
> >Provide refcount_t, an atomic_t like primitive built just for
> >refcounting.  It provides overflow and underflow checks as well as
> >saturation semantics such that when it overflows, we'll never attempt
> >to free it again, ever.
> 
> >Peter do you have the changes to the refcount_t interface compare to
> >the version in this patch?  We are now starting working on atomic_t
> >--> refcount_t conversions and it would save a bit of work to have
> >latest version from you that we can be based upon. 
> 
> Oh, and if we define refcount_t to be just atomic_t underneath, what
> about the other atomic_long_t, local_t and atomic64_t cases when it is
> used for recounting?  I don't feel good just simply changing them to
> become atomic_t under refcount_t wrapper..... 

Is there anybody using local_t ? That seems 'creative' and highly
questionable.

As for atomic_long_t there's very few, I'd leave them be for now, and I
couldn't find a single atomic64_t refcount user.