linux-kernel - Re: [PATCH RFC] mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY

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Message-Id: <20170125200708.GG3989@linux.vnet.ibm.com>
Date:   Wed, 25 Jan 2017 12:07:08 -0800
From:   "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     Christoph Lameter <cl@...ux.com>, willy@...radead.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        penberg@...nel.org, rientjes@...gle.com, iamjoonsoo.kim@....com,
        akpm@...ux-foundation.org
Subject: Re: [PATCH RFC] mm: Rename SLAB_DESTROY_BY_RCU to
 SLAB_TYPESAFE_BY_RCU

On Wed, Jan 25, 2017 at 09:04:47AM -0800, Eric Dumazet wrote:
> On Wed, 2017-01-25 at 10:45 -0600, Christoph Lameter wrote:
> > On Sun, 22 Jan 2017, Paul E. McKenney wrote:
> > 
> > > On Wed, Jan 18, 2017 at 06:00:24PM -0600, Christoph Lameter wrote:
> > > > On Wed, 18 Jan 2017, Paul E. McKenney wrote:
> > > >
> > > > > Actually, slab is using RCU to provide type safety to those slab users
> > > > > who request it.
> > > >
> > > > Typesafety is a side effect. The main idea here is that the object can
> > > > still be accessed in RCU sections after another processor frees the
> > > > object. We guarantee that the object is not freed but it may be reused
> > > > for another object within the RCU period.
> > > >
> > > > Can we have a name that expresses all of that properly?
> > >
> > > But of course!!!  "Type safety".  http://wiki.c2.com/?TypeSafe
> > 
> > Well that does not convey the idea that RCU is involved here.
> > 
> > SLAB_DESTROY_RCU_TYPESAFE
> 
> Not clear why we need to change this very fine name ?
> 
> SLAB_DESTROY_BY_RCU was only used by few of us, we know damn well what
> it means.
> 
> Consider we wont be able to change it in various web pages / archives /
> changelogs.

The reason I proposed this change is that I ran into some people last
week who had burned some months learning that this very fine flag
provides only type safety, not identity safety.

Other proposals?

							Thanx, Paul