linux-kernel - Re: [RFC][PATCH 2/7] kref: Add kref

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Date:   Thu, 17 Nov 2016 13:43:39 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     David Windsor <dave@...gbits.org>
Cc:     Kees Cook <keescook@...omium.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        Will Deacon <will.deacon@....com>,
        "Reshetova, Elena" <elena.reshetova@...el.com>,
        Arnd Bergmann <arnd@...db.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>
Subject: Re: [RFC][PATCH 2/7] kref: Add kref_read()

On Thu, Nov 17, 2016 at 07:30:29AM -0500, David Windsor wrote:
> On Thu, Nov 17, 2016 at 3:34 AM, Peter Zijlstra <peterz@...radead.org> wrote:
> > No, its not a statistic. Also, I'm far from convinced stats_t is an
> > actually useful thing to have.
> >
> 
> Regarding this, has there been any thought given as to how stats_t
> will meaningfully differ from atomic_t?  If refcount_t is semantically
> "atomic_t with reference counter overflow protection," what
> services/guarantees does stats_t provide?  I cannot think of any that
> don't require implementing overflow detection of some sort, which
> incurs a performance hit.

Afaict the whole point of stats_t was to allow overflow, since its only
stats, nobody cares etc..

I think the sole motivator is a general distaste of atomic_t, which
isn't a good reason at all.