[PATCH tip/core/rcu 6/6] rcu: Make rcutorture fakewriters invoke rcu_barrier()

["Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>]

From: "Paul E. McKenney" <paul.mckenney@xxxxxxxxxx>

The current rcutorture rcu_barrier() testing never intentionally runs
more than one instance of rcu_barrier() at a given time.  This fails
to test the the shiny new concurrency features of rcu_barrier().  This
commit therefore modifies the rcutorture fakewriter kthread to randomly
invoke rcu_barrier() rather than the usual synchronize_rcu().

Signed-off-by: Paul E. McKenney <paul.mckenney@xxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
 kernel/rcutorture.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index 54a3745..dfb4e20 100644
--- a/kernel/rcutorture.c
+++ b/kernel/rcutorture.c
@@ -1025,7 +1025,11 @@ rcu_torture_fakewriter(void *arg)
 	do {
 		schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 		udelay(rcu_random(&rand) & 0x3ff);
-		cur_ops->sync();
+		if (cur_ops->cb_barrier != NULL &&
+		    rcu_random(&rand) % (NR_CPUS * 8) == 0)
+			cur_ops->cb_barrier();
+		else
+			cur_ops->sync();
 		rcu_stutter_wait("rcu_torture_fakewriter");
 	} while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 
-- 
1.7.8

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