Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar:
 "The biggest part of this tree is the new auto-generated atomics API
  wrappers by Mark Rutland.

  The primary motivation was to allow instrumentation without uglifying
  the primary source code.

  The linecount increase comes from adding the auto-generated files to
  the Git space as well:

    include/asm-generic/atomic-instrumented.h     | 1689 ++++++++++++++++--
    include/asm-generic/atomic-long.h             | 1174 ++++++++++---
    include/linux/atomic-fallback.h               | 2295 +++++++++++++++++++++++++
    include/linux/atomic.h                        | 1241 +------------

  I preferred this approach, so that the full call stack of the (already
  complex) locking APIs is still fully visible in 'git grep'.

  But if this is excessive we could certainly hide them.

  There's a separate build-time mechanism to determine whether the
  headers are out of date (they should never be stale if we do our job
  right).

  Anyway, nothing from this should be visible to regular kernel
  developers.

  Other changes:

   - Add support for dynamic keys, which removes a source of false
     positives in the workqueue code, among other things (Bart Van
     Assche)

   - Updates to tools/memory-model (Andrea Parri, Paul E. McKenney)

   - qspinlock, wake_q and lockdep micro-optimizations (Waiman Long)

   - misc other updates and enhancements"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (48 commits)
  locking/lockdep: Shrink struct lock_class_key
  locking/lockdep: Add module_param to enable consistency checks
  lockdep/lib/tests: Test dynamic key registration
  lockdep/lib/tests: Fix run_tests.sh
  kernel/workqueue: Use dynamic lockdep keys for workqueues
  locking/lockdep: Add support for dynamic keys
  locking/lockdep: Verify whether lock objects are small enough to be used as class keys
  locking/lockdep: Check data structure consistency
  locking/lockdep: Reuse lock chains that have been freed
  locking/lockdep: Fix a comment in add_chain_cache()
  locking/lockdep: Introduce lockdep_next_lockchain() and lock_chain_count()
  locking/lockdep: Reuse list entries that are no longer in use
  locking/lockdep: Free lock classes that are no longer in use
  locking/lockdep: Update two outdated comments
  locking/lockdep: Make it easy to detect whether or not inside a selftest
  locking/lockdep: Split lockdep_free_key_range() and lockdep_reset_lock()
  locking/lockdep: Initialize the locks_before and locks_after lists earlier
  locking/lockdep: Make zap_class() remove all matching lock order entries
  locking/lockdep: Reorder struct lock_class members
  locking/lockdep: Avoid that add_chain_cache() adds an invalid chain to the cache
  ...

1 files changed, 21 insertions, 3 deletions

diff --git a/Documentation/core-api/refcount-vs-atomic.rst b/Documentation/core-api/refcount-vs-atomic.rst
index 322851bada16..976e85adffe8 100644
--- a/Documentation/core-api/refcount-vs-atomic.rst
+++ b/Documentation/core-api/refcount-vs-atomic.rst
@@ -54,6 +54,13 @@ must propagate to all other CPUs before the release operation
 (A-cumulative property). This is implemented using
 :c:func:`smp_store_release`.
 
+An ACQUIRE memory ordering guarantees that all post loads and
+stores (all po-later instructions) on the same CPU are
+completed after the acquire operation. It also guarantees that all
+po-later stores on the same CPU must propagate to all other CPUs
+after the acquire operation executes. This is implemented using
+:c:func:`smp_acquire__after_ctrl_dep`.
+
 A control dependency (on success) for refcounters guarantees that
 if a reference for an object was successfully obtained (reference
 counter increment or addition happened, function returned true),
@@ -119,13 +126,24 @@ Memory ordering guarantees changes:
    result of obtaining pointer to the object!
 
 
-case 5) - decrement-based RMW ops that return a value
------------------------------------------------------
+case 5) - generic dec/sub decrement-based RMW ops that return a value
+---------------------------------------------------------------------
 
 Function changes:
 
  * :c:func:`atomic_dec_and_test` --> :c:func:`refcount_dec_and_test`
  * :c:func:`atomic_sub_and_test` --> :c:func:`refcount_sub_and_test`
+
+Memory ordering guarantees changes:
+
+ * fully ordered --> RELEASE ordering + ACQUIRE ordering on success
+
+
+case 6) other decrement-based RMW ops that return a value
+---------------------------------------------------------
+
+Function changes:
+
  * no atomic counterpart --> :c:func:`refcount_dec_if_one`
  * ``atomic_add_unless(&var, -1, 1)`` --> ``refcount_dec_not_one(&var)``
 
@@ -136,7 +154,7 @@ Memory ordering guarantees changes:
 .. note:: :c:func:`atomic_add_unless` only provides full order on success.
 
 
-case 6) - lock-based RMW
+case 7) - lock-based RMW
 ------------------------
 
 Function changes: