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

Pull locking updates from Ingo Molnar:

 - Add 'cross-release' support to lockdep, which allows APIs like
   completions, where it's not the 'owner' who releases the lock, to be
   tracked. It's all activated automatically under
   CONFIG_PROVE_LOCKING=y.

 - Clean up (restructure) the x86 atomics op implementation to be more
   readable, in preparation of KASAN annotations. (Dmitry Vyukov)

 - Fix static keys (Paolo Bonzini)

 - Add killable versions of down_read() et al (Kirill Tkhai)

 - Rework and fix jump_label locking (Marc Zyngier, Paolo Bonzini)

 - Rework (and fix) tlb_flush_pending() barriers (Peter Zijlstra)

 - Remove smp_mb__before_spinlock() and convert its usages, introduce
   smp_mb__after_spinlock() (Peter Zijlstra)

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (56 commits)
  locking/lockdep/selftests: Fix mixed read-write ABBA tests
  sched/completion: Avoid unnecessary stack allocation for COMPLETION_INITIALIZER_ONSTACK()
  acpi/nfit: Fix COMPLETION_INITIALIZER_ONSTACK() abuse
  locking/pvqspinlock: Relax cmpxchg's to improve performance on some architectures
  smp: Avoid using two cache lines for struct call_single_data
  locking/lockdep: Untangle xhlock history save/restore from task independence
  locking/refcounts, x86/asm: Disable CONFIG_ARCH_HAS_REFCOUNT for the time being
  futex: Remove duplicated code and fix undefined behaviour
  Documentation/locking/atomic: Finish the document...
  locking/lockdep: Fix workqueue crossrelease annotation
  workqueue/lockdep: 'Fix' flush_work() annotation
  locking/lockdep/selftests: Add mixed read-write ABBA tests
  mm, locking/barriers: Clarify tlb_flush_pending() barriers
  locking/lockdep: Make CONFIG_LOCKDEP_CROSSRELEASE and CONFIG_LOCKDEP_COMPLETIONS truly non-interactive
  locking/lockdep: Explicitly initialize wq_barrier::done::map
  locking/lockdep: Rename CONFIG_LOCKDEP_COMPLETE to CONFIG_LOCKDEP_COMPLETIONS
  locking/lockdep: Reword title of LOCKDEP_CROSSRELEASE config
  locking/lockdep: Make CONFIG_LOCKDEP_CROSSRELEASE part of CONFIG_PROVE_LOCKING
  locking/refcounts, x86/asm: Implement fast refcount overflow protection
  locking/lockdep: Fix the rollback and overwrite detection logic in crossrelease
  ...

1 files changed, 8 insertions, 93 deletions

diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt
index e2ee0a1c299a..b759a60624fd 100644
--- a/Documentation/memory-barriers.txt
+++ b/Documentation/memory-barriers.txt
@@ -498,11 +498,11 @@ And a couple of implicit varieties:
      This means that ACQUIRE acts as a minimal "acquire" operation and
      RELEASE acts as a minimal "release" operation.
 
-A subset of the atomic operations described in core-api/atomic_ops.rst have
-ACQUIRE and RELEASE variants in addition to fully-ordered and relaxed (no
-barrier semantics) definitions.  For compound atomics performing both a load
-and a store, ACQUIRE semantics apply only to the load and RELEASE semantics
-apply only to the store portion of the operation.
+A subset of the atomic operations described in atomic_t.txt have ACQUIRE and
+RELEASE variants in addition to fully-ordered and relaxed (no barrier
+semantics) definitions.  For compound atomics performing both a load and a
+store, ACQUIRE semantics apply only to the load and RELEASE semantics apply
+only to the store portion of the operation.
 
 Memory barriers are only required where there's a possibility of interaction
 between two CPUs or between a CPU and a device.  If it can be guaranteed that
@@ -1883,8 +1883,7 @@ There are some more advanced barrier functions:
      This makes sure that the death mark on the object is perceived to be set
      *before* the reference counter is decremented.
 
-     See Documentation/core-api/atomic_ops.rst for more information.  See the
-     "Atomic operations" subsection for information on where to use these.
+     See Documentation/atomic_{t,bitops}.txt for more information.
 
 
  (*) lockless_dereference();
@@ -1989,10 +1988,7 @@ for each construct.  These operations all imply certain barriers:
      ACQUIRE operation has completed.
 
      Memory operations issued before the ACQUIRE may be completed after
-     the ACQUIRE operation has completed.  An smp_mb__before_spinlock(),
-     combined with a following ACQUIRE, orders prior stores against
-     subsequent loads and stores.  Note that this is weaker than smp_mb()!
-     The smp_mb__before_spinlock() primitive is free on many architectures.
+     the ACQUIRE operation has completed.
 
  (2) RELEASE operation implication:
 
@@ -2510,88 +2506,7 @@ operations are noted specially as some of them imply full memory barriers and
 some don't, but they're very heavily relied on as a group throughout the
 kernel.
 
-Any atomic operation that modifies some state in memory and returns information
-about the state (old or new) implies an SMP-conditional general memory barrier
-(smp_mb()) on each side of the actual operation (with the exception of
-explicit lock operations, described later).  These include:
-
-	xchg();
-	atomic_xchg();			atomic_long_xchg();
-	atomic_inc_return();		atomic_long_inc_return();
-	atomic_dec_return();		atomic_long_dec_return();
-	atomic_add_return();		atomic_long_add_return();
-	atomic_sub_return();		atomic_long_sub_return();
-	atomic_inc_and_test();		atomic_long_inc_and_test();
-	atomic_dec_and_test();		atomic_long_dec_and_test();
-	atomic_sub_and_test();		atomic_long_sub_and_test();
-	atomic_add_negative();		atomic_long_add_negative();
-	test_and_set_bit();
-	test_and_clear_bit();
-	test_and_change_bit();
-
-	/* when succeeds */
-	cmpxchg();
-	atomic_cmpxchg();		atomic_long_cmpxchg();
-	atomic_add_unless();		atomic_long_add_unless();
-
-These are used for such things as implementing ACQUIRE-class and RELEASE-class
-operations and adjusting reference counters towards object destruction, and as
-such the implicit memory barrier effects are necessary.
-
-
-The following operations are potential problems as they do _not_ imply memory
-barriers, but might be used for implementing such things as RELEASE-class
-operations:
-
-	atomic_set();
-	set_bit();
-	clear_bit();
-	change_bit();
-
-With these the appropriate explicit memory barrier should be used if necessary
-(smp_mb__before_atomic() for instance).
-
-
-The following also do _not_ imply memory barriers, and so may require explicit
-memory barriers under some circumstances (smp_mb__before_atomic() for
-instance):
-
-	atomic_add();
-	atomic_sub();
-	atomic_inc();
-	atomic_dec();
-
-If they're used for statistics generation, then they probably don't need memory
-barriers, unless there's a coupling between statistical data.
-
-If they're used for reference counting on an object to control its lifetime,
-they probably don't need memory barriers because either the reference count
-will be adjusted inside a locked section, or the caller will already hold
-sufficient references to make the lock, and thus a memory barrier unnecessary.
-
-If they're used for constructing a lock of some description, then they probably
-do need memory barriers as a lock primitive generally has to do things in a
-specific order.
-
-Basically, each usage case has to be carefully considered as to whether memory
-barriers are needed or not.
-
-The following operations are special locking primitives:
-
-	test_and_set_bit_lock();
-	clear_bit_unlock();
-	__clear_bit_unlock();
-
-These implement ACQUIRE-class and RELEASE-class operations.  These should be
-used in preference to other operations when implementing locking primitives,
-because their implementations can be optimised on many architectures.
-
-[!] Note that special memory barrier primitives are available for these
-situations because on some CPUs the atomic instructions used imply full memory
-barriers, and so barrier instructions are superfluous in conjunction with them,
-and in such cases the special barrier primitives will be no-ops.
-
-See Documentation/core-api/atomic_ops.rst for more information.
+See Documentation/atomic_t.txt for more information.
 
 
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