commit 66dfcd4a50c0bec0581958effa9a50d25c395eac
author Paul E. McKenney <paulmck@linux.vnet.ibm.com> Mon Oct 16 11:23:42 2017 -0700
committer Paul E. McKenney <paulmck@linux.vnet.ibm.com> Wed Oct 18 13:37:33 2017 -0700
tree 52d9dd1b795da3751275e35ba11fd4e89b787a46
parent 99936e1db6c39809d8f51c1e3c4b684427db2bd2

rcutorture: Preempt RCU-preempt readers more vigorously

This commit attempts to make a very rare rcutorture failure happen
more often by increasing the fraction of RCU-preempt read-side critical
sections that are preempted.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

kernel/rcu/rcutorture.c

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 1a3530e..c0160e3 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -316,7 +316,7 @@ static void rcu_read_delay(struct torture_random_state *rrsp)
 	if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 		udelay(shortdelay_us);
 	if (!preempt_count() &&
-	    !(torture_random(rrsp) % (nrealreaders * 20000)))
+	    !(torture_random(rrsp) % (nrealreaders * 500)))
 		torture_preempt_schedule();  /* QS only if preemptible. */
 }