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Message-ID: <20151204234125.GA21380@linux.vnet.ibm.com>
Date: Fri, 4 Dec 2015 15:41:25 -0800
From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To: linux-kernel@...r.kernel.org
Cc: mingo@...nel.org, jiangshanlai@...il.com, dipankar@...ibm.com,
akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
dvhart@...ux.intel.com, fweisbec@...il.com, oleg@...hat.com,
bobby.prani@...il.com
Subject: [PATCH tip/core/rcu 0/2] Enforce RCU grace-period transitivity
Hello!
Within RCU, acquisitions of the rcu_node structure's ->lock field must
be followed by smp_mb__after_unlock_lock() in order to enforce RCU's
grace-period memory-ordering guarantees. In theory, acquisitions for
debug purposes need not have smp_mb__after_unlock_lock(), but in practice,
anything other than fully consistent enforcement of this rule is a recipe
for disaster. This series therefore adds smp_mb__after_unlock_lock()
for consistency:
1. Create wrapper functions to minimize the number of these
smp_mb__after_unlock_lock() calls, and apply these wrapper
functions throughout. Courtesy of Peter Zijlstra.
2. Catch up wrapper-function application to patches that were
in flight at the time #1 was created.
Thanx, Paul
------------------------------------------------------------------------
b/kernel/rcu/tree.c | 102 ++++++++++++++++-----------------------------
b/kernel/rcu/tree.h | 39 +++++++++++++++++
b/kernel/rcu/tree_plugin.h | 20 +++-----
b/kernel/rcu/tree_trace.c | 2
4 files changed, 85 insertions(+), 78 deletions(-)
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