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[PATCH memory-barriers.txt 7/7] Documentation,barriers: Mention smp_cond_acquire()

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  [PATCH memory-barriers.txt 7/7] Documentation,barriers: Mention smp_cond_acquire() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-04-12 18:00 +0200
    [tip:locking/core] locking/Documentation: Mention  smp_cond_acquire() tip-bot for Davidlohr Bueso <tipbot@zytor.com> - 2016-04-13 09:40 +0200
    Re: [PATCH memory-barriers.txt 7/7] Documentation,barriers: Mention  smp_cond_acquire() Peter Zijlstra <peterz@infradead.org> - 2016-04-13 15:00 +0200
      Re: [PATCH memory-barriers.txt 7/7] Documentation,barriers: Mention  smp_cond_acquire() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-04-13 16:20 +0200

#1376981 — [PATCH memory-barriers.txt 7/7] Documentation,barriers: Mention smp_cond_acquire()

From: Davidlohr Bueso <dave@stgolabs.net>

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

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 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 7133626a61d0..a9454b1c73bd 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.
-- 
2.5.2

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#1377607 — [tip:locking/core] locking/Documentation: Mention smp_cond_acquire()

Commit-ID:  787df6383caa1338a4f6640d71917bc2d8c068b1
Gitweb:     http://git.kernel.org/tip/787df6383caa1338a4f6640d71917bc2d8c068b1
Author:     Davidlohr Bueso <dave@stgolabs.net>
AuthorDate: Tue, 12 Apr 2016 08:52:55 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
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@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bobby.prani@gmail.com
Cc: dhowells@redhat.com
Cc: dipankar@in.ibm.com
Cc: dvhart@linux.intel.com
Cc: edumazet@google.com
Cc: fweisbec@gmail.com
Cc: jiangshanlai@gmail.com
Cc: josh@joshtriplett.org
Cc: mathieu.desnoyers@efficios.com
Cc: oleg@redhat.com
Cc: rostedt@goodmis.org
Link: http://lkml.kernel.org/r/1460476375-27803-7-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 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.

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#1377904 — Re: [PATCH memory-barriers.txt 7/7] Documentation,barriers: Mention smp_cond_acquire()

On Tue, Apr 12, 2016 at 08:52:55AM -0700, Paul E. McKenney wrote:
> From: Davidlohr Bueso <dave@stgolabs.net>
> 
> ... do this next to smp_load_acquire when first mentioning
> ACQUIRE. While this call is briefly explained and ctrl
> dependencies are mentioned later, it does not hurt the reader.

Ha! just when I have a patch set in RFC to change the whole thing about
:-)

lkml.kernel.org/r/20160404122250.340636238@infradead.org

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#1377980 — Re: [PATCH memory-barriers.txt 7/7] Documentation,barriers: Mention smp_cond_acquire()

On Wed, Apr 13, 2016 at 02:53:10PM +0200, Peter Zijlstra wrote:
> On Tue, Apr 12, 2016 at 08:52:55AM -0700, Paul E. McKenney wrote:
> > From: Davidlohr Bueso <dave@stgolabs.net>
> > 
> > ... do this next to smp_load_acquire when first mentioning
> > ACQUIRE. While this call is briefly explained and ctrl
> > dependencies are mentioned later, it does not hurt the reader.
> 
> Ha! just when I have a patch set in RFC to change the whole thing about
> :-)
> 
> lkml.kernel.org/r/20160404122250.340636238@infradead.org

Heh!  I was talking to a bunch of formal-verification researchers last
week, and the fact that requirements can change over time did not make
them feel comfortable.  ;-)

							Thanx, Paul

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