Re: [PATCH v2 RFC 1/3] documentation: Add needed ACCESS_ONCE() calls to memory-barriers.txt

Peter Zijlstra
2013-11-21T22:19:11Z

On Thu, Nov 21, 2013 at 02:09:51PM -0800, Paul E. McKenney wrote:
> On Thu, Nov 21, 2013 at 10:55:17PM +0100, Peter Zijlstra wrote:
> > On Thu, Nov 21, 2013 at 01:31:27PM -0800, Paul E. McKenney wrote:
> > > From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
> > >
> > > The Documentation/memory-barriers.txt file was written before the need
> > > for ACCESS_ONCE() was fully appreciated. It therefore contains no
> > > ACCESS_ONCE() calls, which can be a problem when people lift examples
> > > from it. This commit therefore adds ACCESS_ONCE() calls.
> >
> > So I find the repeated ACCESS_ONCE() significantly detracts from the
> > readability of the text.
> >
> > Can't we simply state that all accesses are assumed single-copy atomic
> > and this can be achieved for naturally aligned words using ACCESS_ONCE()
> > in C/C++ ?
>
> We could, but at the moment I would prefer the decrease in readability
> to the copy-and-paste bugs that omit needed ACCESS_ONCE() calls.
>
> Is there some way to get both ACCESS_ONCE() and readability? An
> abbreviation such as AO()? More easily distinguished variable names?
> Something else?

Use a form that looks less like C and thus defeats copy/paste?