Documentation/litmus-tests: Merge atomic's README into top-level one

LITMUS TESTS

============

Each subdirectory contains litmus tests that are typical to describe the

semantics of respective kernel APIs.

For more information about how to "run" a litmus test or how to generate

a kernel test module based on a litmus test, please see

tools/memory-model/README.

atomic (/atomic derectory)

--------------------------

Atomic-RMW+mb__after_atomic-is-stronger-than-acquire.litmus

    Test that an atomic RMW followed by a smp_mb__after_atomic() is

    stronger than a normal acquire: both the read and write parts of

    the RMW are ordered before the subsequential memory accesses.

Atomic-RMW-ops-are-atomic-WRT-atomic_set.litmus

    Test that atomic_set() cannot break the atomicity of atomic RMWs.

RCU (/rcu directory)

--------------------

This directory contains litmus tests that are typical to describe the semantics

of our atomic APIs. For more information about how to "run" a litmus test or

how to generate a kernel test module based on a litmus test, please see

tools/memory-model/README.

============

LITMUS TESTS

============

Atomic-RMW+mb__after_atomic-is-stronger-than-acquire

	Test that an atomic RMW followed by a smp_mb__after_atomic() is

	stronger than a normal acquire: both the read and write parts of

	the RMW are ordered before the subsequential memory accesses.

Atomic-RMW-ops-are-atomic-WRT-atomic_set.litmus

	Test that atomic_set() cannot break the atomicity of atomic RMWs.