Merge branch 'kcsan.2020.01.07a' into locking/kcsan

Selective analysis

~~~~~~~~~~~~~~~~~~

To disable KCSAN data race detection for an entire subsystem, add to the

respective ``Makefile``::

It may be desirable to disable data race detection for specific accesses,

functions, compilation units, or entire subsystems.  For static blacklisting,

the below options are available:

    KCSAN_SANITIZE := n

* KCSAN understands the ``data_race(expr)`` annotation, which tells KCSAN that

  any data races due to accesses in ``expr`` should be ignored and resulting

  behaviour when encountering a data race is deemed safe.

* Disabling data race detection for entire functions can be accomplished by

  using the function attribute ``__no_kcsan`` (or ``__no_kcsan_or_inline`` for

  ``__always_inline`` functions). To dynamically control for which functions

  data races are reported, see the `debugfs`_ blacklist/whitelist feature.

To disable KCSAN on a per-file basis, add to the ``Makefile``::

* To disable data race detection for a particular compilation unit, add to the

  ``Makefile``::

    KCSAN_SANITIZE_file.o := n

KCSAN also understands the ``data_race(expr)`` annotation, which tells KCSAN

that any data races due to accesses in ``expr`` should be ignored and resulting

behaviour when encountering a data race is deemed safe.

* To disable data race detection for all compilation units listed in a

  ``Makefile``, add to the respective ``Makefile``::

    KCSAN_SANITIZE := n

debugfs

~~~~~~~

#endif

#if defined(__SANITIZE_THREAD__) && __has_attribute(__no_sanitize_thread__)

#define __no_sanitize_thread                                                   \

	__attribute__((__noinline__)) __attribute__((no_sanitize_thread))

#define __no_sanitize_thread __attribute__((no_sanitize_thread))

#else

#define __no_sanitize_thread

#endif