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Subject[PATCH] RCU read sched
(probably already in -tip)

Add rcu_read_lock_sched() and rcu_read_unlock_sched() to rcupdate.h to match the
recently added write-side call_rcu_sched() and rcu_barrier_sched(). They also
match the no-so-recently-added synchronize_sched().

It will help following matching use of the update/read lock primitives. Those
new read lock will replace preempt_disable()/enable() used in pair with
RCU-classic synchronization.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Acked-by: Peter Zijlstra <peterz@infradead.org>
CC: Paul E McKenney <paulmck@linux.vnet.ibm.com>
CC: akpm@linux-foundation.org
---
include/linux/rcupdate.h | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)

Index: linux-2.6-lttng/include/linux/rcupdate.h
===================================================================
--- linux-2.6-lttng.orig/include/linux/rcupdate.h 2008-07-15 15:18:20.000000000 -0400
+++ linux-2.6-lttng/include/linux/rcupdate.h 2008-07-15 15:18:46.000000000 -0400
@@ -132,6 +132,26 @@ struct rcu_head {
#define rcu_read_unlock_bh() __rcu_read_unlock_bh()

/**
+ * rcu_read_lock_sched - mark the beginning of a RCU-classic critical section
+ *
+ * Should be used with either
+ * - synchronize_sched()
+ * or
+ * - call_rcu_sched() and rcu_barrier_sched()
+ * on the write-side to insure proper synchronization.
+ */
+#define rcu_read_lock_sched() preempt_disable()
+
+/*
+ * rcu_read_unlock_sched - marks the end of a RCU-classic critical section
+ *
+ * See rcu_read_lock_sched for more information.
+ */
+#define rcu_read_unlock_sched() preempt_enable()
+
+
+
+/**
* rcu_dereference - fetch an RCU-protected pointer in an
* RCU read-side critical section. This pointer may later
* be safely dereferenced.
--
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68

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