[PATCH tip/core/rcu 5/6] rcutorture: Add RCU-tasks qualifier to dereference

Paul E. McKenney
2015-07-17T23:45:54Z

Although RCU-tasks isn't really designed to support rcu_dereference()
and list manipulation, that is how rcutorture tests it. Which means
that lockdep-RCU complains about the rcu_dereference_check() invocations
because RCU-tasks doesn't have read-side markers. This commit therefore
creates a torturing_tasks() to silence the lockdep-RCU complaints from
rcu_dereference_check() when RCU-tasks is being tortured.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
kernel/rcu/rcutorture.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index e0eda3c1b621..67b3f260720e 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -684,10 +684,20 @@ static struct rcu_torture_ops tasks_ops = {

#define RCUTORTURE_TASKS_OPS &tasks_ops,

+static bool __maybe_unused torturing_tasks(void)
+{
+ return cur_ops == &tasks_ops;
+}
+
#else /* #ifdef CONFIG_TASKS_RCU */

#define RCUTORTURE_TASKS_OPS

+static bool torturing_tasks(void)
+{
+ return false;
+}
+
#endif /* #else #ifdef CONFIG_TASKS_RCU */

/*
@@ -1087,7 +1097,8 @@ static void rcu_torture_timer(unsigned long unused)
p = rcu_dereference_check(rcu_torture_current,
rcu_read_lock_bh_held() ||
rcu_read_lock_sched_held() ||
- srcu_read_lock_held(srcu_ctlp));
+ srcu_read_lock_held(srcu_ctlp) ||
+ torturing_tasks());
if (p == NULL) {
/* Leave because rcu_torture_writer is not yet underway */
cur_ops->readunlock(idx);
@@ -1161,7 +1172,8 @@ rcu_torture_reader(void *arg)
p = rcu_dereference_check(rcu_torture_current,
rcu_read_lock_bh_held() ||
rcu_read_lock_sched_held() ||
- srcu_read_lock_held(srcu_ctlp));
+ srcu_read_lock_held(srcu_ctlp) ||
+ torturing_tasks());
if (p == NULL) {
/* Wait for rcu_torture_writer to get underway */
cur_ops->readunlock(idx);
--
1.8.1.5