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  headers are out of date (they should never be stale if we do our job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  locking/lockdep: Update two outdated comments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, 4 insertions, 20 deletions

diff --git a/include/linux/percpu-rwsem.h b/include/linux/percpu-rwsem.h
index 71b75643c432..03cb4b6f842e 100644
--- a/include/linux/percpu-rwsem.h
+++ b/include/linux/percpu-rwsem.h
@@ -29,7 +29,7 @@ static struct percpu_rw_semaphore name = {				\
 extern int __percpu_down_read(struct percpu_rw_semaphore *, int);
 extern void __percpu_up_read(struct percpu_rw_semaphore *);
 
-static inline void percpu_down_read_preempt_disable(struct percpu_rw_semaphore *sem)
+static inline void percpu_down_read(struct percpu_rw_semaphore *sem)
 {
 	might_sleep();
 
@@ -47,16 +47,10 @@ static inline void percpu_down_read_preempt_disable(struct percpu_rw_semaphore *
 	__this_cpu_inc(*sem->read_count);
 	if (unlikely(!rcu_sync_is_idle(&sem->rss)))
 		__percpu_down_read(sem, false); /* Unconditional memory barrier */
-	barrier();
 	/*
-	 * The barrier() prevents the compiler from
+	 * The preempt_enable() prevents the compiler from
 	 * bleeding the critical section out.
 	 */
-}
-
-static inline void percpu_down_read(struct percpu_rw_semaphore *sem)
-{
-	percpu_down_read_preempt_disable(sem);
 	preempt_enable();
 }
 
@@ -83,13 +77,9 @@ static inline int percpu_down_read_trylock(struct percpu_rw_semaphore *sem)
 	return ret;
 }
 
-static inline void percpu_up_read_preempt_enable(struct percpu_rw_semaphore *sem)
+static inline void percpu_up_read(struct percpu_rw_semaphore *sem)
 {
-	/*
-	 * The barrier() prevents the compiler from
-	 * bleeding the critical section out.
-	 */
-	barrier();
+	preempt_disable();
 	/*
 	 * Same as in percpu_down_read().
 	 */
@@ -102,12 +92,6 @@ static inline void percpu_up_read_preempt_enable(struct percpu_rw_semaphore *sem
 	rwsem_release(&sem->rw_sem.dep_map, 1, _RET_IP_);
 }
 
-static inline void percpu_up_read(struct percpu_rw_semaphore *sem)
-{
-	preempt_disable();
-	percpu_up_read_preempt_enable(sem);
-}
-
 extern void percpu_down_write(struct percpu_rw_semaphore *);
 extern void percpu_up_write(struct percpu_rw_semaphore *);