* [PATCH] rcuperf: Do not wake up shutdown wait queue if "shutdown" is false.
@ 2016-02-07 12:31 Artem Savkov
2016-02-07 19:43 ` Paul E. McKenney
0 siblings, 1 reply; 2+ messages in thread
From: Artem Savkov @ 2016-02-07 12:31 UTC (permalink / raw)
To: paulmck; +Cc: linux-kernel, Artem Savkov
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 <artem.savkov@gmail.com>
---
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
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] rcuperf: Do not wake up shutdown wait queue if "shutdown" is false.
2016-02-07 12:31 [PATCH] rcuperf: Do not wake up shutdown wait queue if "shutdown" is false Artem Savkov
@ 2016-02-07 19:43 ` Paul E. McKenney
0 siblings, 0 replies; 2+ messages in thread
From: Paul E. McKenney @ 2016-02-07 19:43 UTC (permalink / raw)
To: Artem Savkov; +Cc: linux-kernel
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 <artem.savkov@gmail.com>
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
>
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