[PATCH] rcu: add sched torture type to rcutorture

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>
Acked-by: Paul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 42 insertions, 3 deletions

diff --git a/Documentation/RCU/torture.txt b/Documentation/RCU/torture.txt
index cc4b1efe5ea8..25a3c3f7d378 100644
--- a/Documentation/RCU/torture.txt
+++ b/Documentation/RCU/torture.txt
@@ -56,8 +56,9 @@ test_no_idle_hz	Whether or not to test the ability of RCU to operate in
 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 --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index 0f0ff1556b5d..e2bda18f6f42 100644
--- a/kernel/rcutorture.c
+++ b/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