Re: [PATCH] Document Linux's circular buffering capabilities

[David Howells <dhowells@redhat.com>]

Stefan Richter <stefanr@s5r6.in-berlin.de> wrote:

> Would you agree to add a quick note that these examples are simple
> enough to not strictly require ACCESS_ONCE but are meant to show what
> more general code would have to do?  Else a reader might be left puzzled
> why he can't see in the example code the circumstances which require
> ACCESS_ONCE and may remain unsure about where to use it in his own works...

How about adding a bit:

 Note the use of ACCESS_ONCE() in both algorithms to read the opposition index.
 This prevents the compiler from discarding and reloading its cached value -
-which some compilers will do across smp_read_barrier_depends().
+which some compilers will do across smp_read_barrier_depends().  This isn't
+strictly needed if you can be sure that the opposition index will _only_ be
+used the once.

David