[PATCH v4 tip/core/locking 0/4] Memory-barrier documentation updates

["Paul E. McKenney" <paulmck@linux.vnet.ibm.com>]

Hello!

This series applies some long-needed updates to memory-barriers.txt:

1.	Add ACCESS_ONCE() calls where needed to ensure their inclusion
	in code copy-and-pasted from this file.

2.	Add long atomic examples alongside the existing atomics.

3.	Prohibit architectures supporting the Linux kernel from
	speculating stores.

4.	Document what ACCESS_ONCE() does along with a number of situations
	requiring its use.

Changes from v3:

o	Fix typos noted by Peter Zijlstra.

o	Added the documentation about ACCESS_ONCE(), which expands on
	http://thread.gmane.org/gmane.linux.kernel.mm/82891/focus=14696,
	ably summarized by Jon Corbet at http://lwn.net/Articles/508991/.

Changes from v2:

o	Update examples so that that load against which the subsequent
	store is to be ordered is part of the "if" condition.

o	Add an example showing how the compiler can remove "if"
	conditions and how to prevent it from doing so.

o	Add ACCESS_ONCE() to the compiler-barrier section.

o	Add a sentence noting that transitivity requires smp_mb().

Changes from v1:

o	Combined with Peter Zijlstra's speculative-store-prohibition patch.

o	Added more pitfalls to avoid when prohibiting speculative
	stores, along with how to avoid them.

o	Applied Josh Triplett's review comments.

							Thanx, Paul


 b/Documentation/memory-barriers.txt |  666 ++++++++++++++++++++++++++++--------
 1 file changed, 533 insertions(+), 133 deletions(-)