From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: linux-kernel@vger.kernel.org
Cc: mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com,
bobby.prani@gmail.com,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 05/14] documentation: Remove obsolete reference to RCU-protected indexes
Date: Tue, 23 Feb 2016 21:00:38 -0800 [thread overview]
Message-ID: <1456290047-16654-5-git-send-email-paulmck@linux.vnet.ibm.com> (raw)
In-Reply-To: <20160224050021.GA14616@linux.vnet.ibm.com>
Commit #1ebee8017d84 (rcu: Eliminate array-index-based RCU primitives)
eliminated the primitives supporting RCU-protected array indexes, but
failed to update Documentation/memory-barriers.txt accordingly. This
commit therefore removes the discussion of RCU-protected array indexes.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
Documentation/memory-barriers.txt | 15 ---------------
1 file changed, 15 deletions(-)
diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt
index c90922b9b294..6bee0a2c43ab 100644
--- a/Documentation/memory-barriers.txt
+++ b/Documentation/memory-barriers.txt
@@ -565,21 +565,6 @@ odd-numbered bank is idle, one can see the new value of the pointer P (&B),
but the old value of the variable B (2).
-Another example of where data dependency barriers might be required is where a
-number is read from memory and then used to calculate the index for an array
-access:
-
- CPU 1 CPU 2
- =============== ===============
- { M[0] == 1, M[1] == 2, M[3] = 3, P == 0, Q == 3 }
- M[1] = 4;
- <write barrier>
- WRITE_ONCE(P, 1);
- Q = READ_ONCE(P);
- <data dependency barrier>
- D = M[Q];
-
-
The data dependency barrier is very important to the RCU system,
for example. See rcu_assign_pointer() and rcu_dereference() in
include/linux/rcupdate.h. This permits the current target of an RCU'd
--
2.5.2
next prev parent reply other threads:[~2016-02-24 5:08 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-24 5:00 [PATCH tip/core/rcu 0/14] Documentation updates for 4.6 Paul E. McKenney
2016-02-24 5:00 ` [PATCH tip/core/rcu 01/14] documentation: Add real-time requirements from CPU-bound workloads Paul E. McKenney
2016-02-24 5:00 ` [PATCH tip/core/rcu 02/14] documentation: Fix control dependency and identical stores Paul E. McKenney
2016-02-24 21:12 ` Mathieu Desnoyers
2016-02-24 21:40 ` Paul E. McKenney
2016-02-25 6:41 ` Jianyu Zhan
2016-02-25 14:08 ` Paul E. McKenney
2016-02-25 8:21 ` Peter Zijlstra
2016-02-25 14:07 ` Paul E. McKenney
2016-02-25 14:48 ` Peter Zijlstra
2016-02-25 15:42 ` Paul E. McKenney
2016-02-24 5:00 ` [PATCH tip/core/rcu 03/14] documentation: Fix memory-barriers.txt section references Paul E. McKenney
2016-02-24 5:00 ` [PATCH tip/core/rcu 04/14] documentation: Add synchronize_rcu_mult() to the requirements Paul E. McKenney
2016-02-24 5:00 ` Paul E. McKenney [this message]
2016-02-24 5:00 ` [PATCH tip/core/rcu 06/14] documentation: Subsequent writes ordered by rcu_dereference() Paul E. McKenney
2016-02-24 5:00 ` [PATCH tip/core/rcu 07/14] documentation: Distinguish between local and global transitivity Paul E. McKenney
2016-02-24 5:00 ` [PATCH tip/core/rcu 08/14] documentation: Add alternative release-acquire outcome Paul E. McKenney
2016-02-24 5:00 ` [PATCH tip/core/rcu 09/14] documentation: Add documentation for RCU's major data structures Paul E. McKenney
2016-02-24 5:00 ` [PATCH tip/core/rcu 10/14] documentation: Explain why rcu_read_lock() needs no barrier() Paul E. McKenney
2016-02-24 5:00 ` [PATCH tip/core/rcu 11/14] documentation: Transitivity is not cumulativity Paul E. McKenney
2016-02-24 5:00 ` [PATCH tip/core/rcu 12/14] documentation: Document illegality of call_rcu() from offline CPUs Paul E. McKenney
2016-02-24 5:00 ` [PATCH tip/core/rcu 13/14] documentation: Explain how RCU's combining tree fights contention Paul E. McKenney
2016-02-24 5:00 ` [PATCH tip/core/rcu 14/14] documentation: Clarify compiler store-fusion example Paul E. McKenney
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