[tip:locking/core] locking/Documentation: Mention smp_cond_acquire()

[tip-bot for Davidlohr Bueso]

Commit-ID:  787df6383caa1338a4f6640d71917bc2d8c068b1
Gitweb:     http://git.kernel.org/tip/787df6383caa1338a4f6640d71917bc2d8c068b1
Author:     Davidlohr Bueso <dave@xxxxxxxxxxxx>
AuthorDate: Tue, 12 Apr 2016 08:52:55 -0700
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 13 Apr 2016 08:52:23 +0200

locking/Documentation: Mention smp_cond_acquire()

... do this next to smp_load_acquire() when first mentioning
ACQUIRE. While this call is briefly explained and control
dependencies are mentioned later, it does not hurt the reader.

Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: bobby.prani@xxxxxxxxx
Cc: dhowells@xxxxxxxxxx
Cc: dipankar@xxxxxxxxxx
Cc: dvhart@xxxxxxxxxxxxxxx
Cc: edumazet@xxxxxxxxxx
Cc: fweisbec@xxxxxxxxx
Cc: jiangshanlai@xxxxxxxxx
Cc: josh@xxxxxxxxxxxxxxxx
Cc: mathieu.desnoyers@xxxxxxxxxxxx
Cc: oleg@xxxxxxxxxx
Cc: rostedt@xxxxxxxxxxx
Link: http://lkml.kernel.org/r/1460476375-27803-7-git-send-email-paulmck@xxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 Documentation/memory-barriers.txt | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt
index 7133626..a9454b1 100644
--- a/Documentation/memory-barriers.txt
+++ b/Documentation/memory-barriers.txt
@@ -431,8 +431,9 @@ And a couple of implicit varieties:
      This acts as a one-way permeable barrier.  It guarantees that all memory
      operations after the ACQUIRE operation will appear to happen after the
      ACQUIRE operation with respect to the other components of the system.
-     ACQUIRE operations include LOCK operations and smp_load_acquire()
-     operations.
+     ACQUIRE operations include LOCK operations and both smp_load_acquire()
+     and smp_cond_acquire() operations. The later builds the necessary ACQUIRE
+     semantics from relying on a control dependency and smp_rmb().
 
      Memory operations that occur before an ACQUIRE operation may appear to
      happen after it completes.