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From: Masami Hiramatsu on 22 Mar 2010 14:00
Jason Baron wrote:
> From: Mathieu Desnoyers <mathieu.desnoyers(a)polymtl.ca>
>
> In LTTng, being able to use the atomic notifier from cpu idle entry to
> ensure the tracer flush the last events in the current subbuffer
> requires the rcu read-side to be marked "notrace", otherwise it can end
> up calling back into lockdep and the tracer.
>
> Also apply to the the die notifier.

Looks good for me and it'll be good for kprobe-tracer too:)


>
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers(a)polymtl.ca>
> Signed-off-by: Jason Baron <jbaron(a)redhat.com>

Reviewed-by: Masami Hiramatsu <mhiramat(a)redhat.com>

> ---
> kernel/notifier.c | 6 +++---
> 1 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/notifier.c b/kernel/notifier.c
> index 2488ba7..88453a7 100644
> --- a/kernel/notifier.c
> +++ b/kernel/notifier.c
> @@ -148,7 +148,7 @@ int atomic_notifier_chain_unregister(struct atomic_notifier_head *nh,
> spin_lock_irqsave(&nh->lock, flags);
> ret = notifier_chain_unregister(&nh->head, n);
> spin_unlock_irqrestore(&nh->lock, flags);
> - synchronize_rcu();
> + synchronize_sched();
> return ret;
> }
> EXPORT_SYMBOL_GPL(atomic_notifier_chain_unregister);
> @@ -178,9 +178,9 @@ int __kprobes __atomic_notifier_call_chain(struct atomic_notifier_head *nh,
> {
> int ret;
>
> - rcu_read_lock();
> + rcu_read_lock_sched_notrace();
> ret = notifier_call_chain(&nh->head, val, v, nr_to_call, nr_calls);
> - rcu_read_unlock();
> + rcu_read_unlock_sched_notrace();
> return ret;
> }
> EXPORT_SYMBOL_GPL(__atomic_notifier_call_chain);

--
Masami Hiramatsu
e-mail: mhiramat(a)redhat.com
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Prev: [PATCH] Protect device shutdown from hot unplug events.
Next: HID:HID-NTRIG update ntrig_event function