From: Josh Triplett <josht@us.ibm.com>

Implement torture testing for the "sched" variant of RCU, which uses
preempt_disable, preempt_enable, and synchronize_sched.

Signed-off-by: Josh Triplett <josh@freedesktop.org>
---

index cc4b1ef..25a3c3f 100644
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 Documentation/RCU/torture.txt |    5 ++--
 kernel/rcutorture.c           |   40 +++++++++++++++++++++++++++++++-
 2 files changed, 42 insertions(+), 3 deletions(-)

diff -puN Documentation/RCU/torture.txt~rcu-add-sched-torture-type-to-rcutorture Documentation/RCU/torture.txt
--- a/Documentation/RCU/torture.txt~rcu-add-sched-torture-type-to-rcutorture
+++ a/Documentation/RCU/torture.txt
@@ -56,8 +56,9 @@ test_no_idle_hz	Whether or not to test t
 torture_type	The type of RCU to test: "rcu" for the rcu_read_lock() API,
 		"rcu_sync" for rcu_read_lock() with synchronous reclamation,
 		"rcu_bh" for the rcu_read_lock_bh() API, "rcu_bh_sync" for
-		rcu_read_lock_bh() with synchronous reclamation, and "srcu"
-		for the "srcu_read_lock()" API.
+		rcu_read_lock_bh() with synchronous reclamation, "srcu" for
+		the "srcu_read_lock()" API, and "sched" for the use of
+		preempt_disable() together with synchronize_sched().
 
 verbose		Enable debug printk()s.  Default is disabled.
 
diff -puN kernel/rcutorture.c~rcu-add-sched-torture-type-to-rcutorture kernel/rcutorture.c
--- a/kernel/rcutorture.c~rcu-add-sched-torture-type-to-rcutorture
+++ a/kernel/rcutorture.c
@@ -464,9 +464,47 @@ static struct rcu_torture_ops srcu_ops =
 	.name = "srcu"
 };
 
+/*
+ * Definitions for sched torture testing.
+ */
+
+static int sched_torture_read_lock(void)
+{
+	preempt_disable();
+	return 0;
+}
+
+static void sched_torture_read_unlock(int idx)
+{
+	preempt_enable();
+}
+
+static int sched_torture_completed(void)
+{
+	return 0;
+}
+
+static void sched_torture_synchronize(void)
+{
+	synchronize_sched();
+}
+
+static struct rcu_torture_ops sched_ops = {
+	.init = rcu_sync_torture_init,
+	.cleanup = NULL,
+	.readlock = sched_torture_read_lock,
+	.readdelay = rcu_read_delay,  /* just reuse rcu's version. */
+	.readunlock = sched_torture_read_unlock,
+	.completed = sched_torture_completed,
+	.deferredfree = rcu_sync_torture_deferred_free,
+	.sync = sched_torture_synchronize,
+	.stats = NULL,
+	.name = "sched"
+};
+
 static struct rcu_torture_ops *torture_ops[] =
 	{ &rcu_ops, &rcu_sync_ops, &rcu_bh_ops, &rcu_bh_sync_ops, &srcu_ops,
-	  NULL };
+	  &sched_ops, NULL };
 
 /*
  * RCU torture writer kthread.  Repeatedly substitutes a new structure
_