Merge tag 'locking-urgent-2020-06-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull atomics rework from Thomas Gleixner:
 "Peter Zijlstras rework of atomics and fallbacks. This solves two
  problems:

   1) Compilers uninline small atomic_* static inline functions which
      can expose them to instrumentation.

   2) The instrumentation of atomic primitives was done at the
      architecture level while composites or fallbacks were provided at
      the generic level. As a result there are no uninstrumented
      variants of the fallbacks.

  Both issues were in the way of fully isolating fragile entry code
  pathes and especially the text poke int3 handler which is prone to an
  endless recursion problem when anything in that code path is about to
  be instrumented. This was always a problem, but got elevated due to
  the new batch mode updates of tracing.

  The solution is to mark the functions __always_inline and to flip the
  fallback and instrumentation so the non-instrumented variants are at
  the architecture level and the instrumentation is done in generic
  code.

  The latter introduces another fallback variant which will go away once
  all architectures have been moved over to arch_atomic_*"

* tag 'locking-urgent-2020-06-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/atomics: Flip fallbacks and instrumentation
  asm-generic/atomic: Use __always_inline for fallback wrappers

include/linux/atomic.h

@@ -25,6 +25,12 @@
  * See Documentation/memory-barriers.txt for ACQUIRE/RELEASE definitions.
  */
 
+#define atomic_cond_read_acquire(v, c) smp_cond_load_acquire(&(v)->counter, (c))
+#define atomic_cond_read_relaxed(v, c) smp_cond_load_relaxed(&(v)->counter, (c))
+
+#define atomic64_cond_read_acquire(v, c) smp_cond_load_acquire(&(v)->counter, (c))
+#define atomic64_cond_read_relaxed(v, c) smp_cond_load_relaxed(&(v)->counter, (c))
+
 /*
  * The idea here is to build acquire/release variants by adding explicit
  * barriers on top of the relaxed variant. In the case where the relaxed
@@ -71,7 +77,12 @@
 	__ret;								\
 })
 
+#ifdef ARCH_ATOMIC
+#include <linux/atomic-arch-fallback.h>
+#include <asm-generic/atomic-instrumented.h>
+#else
 #include <linux/atomic-fallback.h>
+#endif
 
 #include <asm-generic/atomic-long.h>