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SubjectRe: [PATCH v5 1/4] ftrace: Implement fs notification for tracing_max_latency
On Tue,  3 Sep 2019 15:25:59 +0200
Viktor Rosendahl <viktor.rosendahl@gmail.com> wrote:

> +void latency_fsnotify_stop(void)
> +{
> + /* Make sure all CPUs see caller's previous actions to stop tracer */
> + smp_wmb();

These memory barriers just look wrong. What exactly are you trying to protect here?

Where's the matching rmbs?

-- Steve

> + static_branch_disable(&latency_notify_key);
> + latency_fsnotify_process();
> +}
> +
> +void latency_fsnotify_start(void)
> +{
> + static_branch_enable(&latency_notify_key);
> + /* Make sure all CPUs see key value before caller continue */
> + smp_wmb();
> +}
> +

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