[PATCH v3 tip/core/locking 0/3] 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.

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