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

Paul E. McKenney
2013-11-21T22:09:59Z

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?

Thanx, Paul