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

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Message-ID: <2236FBA76BA1254E88B949DDB74E612B41C14B3B@IRSMSX102.ger.corp.intel.com>
Date:   Fri, 18 Nov 2016 16:58:52 +0000
From:   "Reshetova, Elena" <elena.reshetova@...el.com>
To:     Peter Zijlstra <peterz@...radead.org>
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?

I wish I understand what you mean by "unwrap"... ?

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.
I am not yet sure about refcounts, but local_t itself is used in couple of places. 

>As for atomic_long_t there's very few, I'd leave them be for now, 
Ok, I have started a list on them to keep track, but we need to do them also. There is no reason for them not to be refcounts, since so far the ones I see are classical refcounts. 

>and I couldn't find a single atomic64_t refcount user.
I will check when I get over the atomic_t and atomic_long.