rcuperf: Do not wake up shutdown wait queue if "shutdown" is false.

After finishing its tests rcuperf tries to wake up shutdown_wq even if
"shutdown" param is set to false, resulting in a wake_up() call on an
unitialized wait_queue_head_t which leads to "BUG: spinlock bad magic" and
"BUG: unable to handle kernel NULL pointer dereference".

Fix by checking "shutdown" param before waking up the queue.

Signed-off-by: Artem Savkov <artem.savkov@gmail.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c
index 4c0572859ff0..3cee0d8393ed 100644
--- a/kernel/rcu/rcuperf.c
+++ b/kernel/rcu/rcuperf.c
@@ -423,8 +423,10 @@ rcu_perf_writer(void *arg)
                                         b_rcu_perf_writer_finished =
                                                 cur_ops->completed();
                                 }
-                                smp_mb(); /* Assign before wake. */
-                                wake_up(&shutdown_wq);
+                                if (shutdown) {
+                                        smp_mb(); /* Assign before wake. */
+                                        wake_up(&shutdown_wq);
+                                }
                         }
                 }
                 if (done && !alldone &&