rcu: Trace only after NULL-pointer check

Fix a bonehead error introduced when adding event tracing to rcutorture.
Move the traces to follow the NULL-pointer checks.

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

diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index 5cfa23be43bd2f625ebd6c96ae462ebfa126c2e8..ed1c72bd9c09eb37eba09ebea6119ba9d8830bb3 100644 (file)
--- a/kernel/rcutorture.c
+++ b/kernel/rcutorture.c
@@ -1000,12 +1000,12 @@ static void rcu_torture_timer(unsigned long unused)
                                  rcu_read_lock_bh_held() ||
                                  rcu_read_lock_sched_held() ||
                                  srcu_read_lock_held(&srcu_ctl));
-       do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
        if (p == NULL) {
                /* Leave because rcu_torture_writer is not yet underway */
                cur_ops->readunlock(idx);
                return;
        }
+       do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
        if (p->rtort_mbtest == 0)
                atomic_inc(&n_rcu_torture_mberror);
        spin_lock(&rand_lock);
@@ -1063,13 +1063,13 @@ rcu_torture_reader(void *arg)
                                          rcu_read_lock_bh_held() ||
                                          rcu_read_lock_sched_held() ||
                                          srcu_read_lock_held(&srcu_ctl));
-               do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
                if (p == NULL) {
                        /* Wait for rcu_torture_writer to get underway */
                        cur_ops->readunlock(idx);
                        schedule_timeout_interruptible(HZ);
                        continue;
                }
+               do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
                if (p->rtort_mbtest == 0)
                        atomic_inc(&n_rcu_torture_mberror);
                cur_ops->read_delay(&rand);