On Sun, Feb 07, 2016 at 01:31:39PM +0100, Artem Savkov wrote:
> After finishing it's 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 <[email protected]>
Good catch! Queued for testing and review.
Thanx, Paul
> ---
> kernel/rcu/rcuperf.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c
> index 09ffa36..fb45a26 100644
> --- a/kernel/rcu/rcuperf.c
> +++ b/kernel/rcu/rcuperf.c
> @@ -414,8 +414,10 @@ 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 &&
> --
> 2.7.0
>
