linux-kernel - Re: [PATCH V4 02/19] trace/osnoise: Split workload start from the tracer start

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Message-ID: <be7cbe08-9657-f5ac-4053-0cf2b9c26a78@kernel.org>
Date:   Mon, 25 Oct 2021 09:33:53 +0200
From:   Daniel Bristot de Oliveira <bristot@...nel.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Ingo Molnar <mingo@...hat.com>, Tom Zanussi <zanussi@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Clark Williams <williams@...hat.com>,
        John Kacur <jkacur@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        linux-rt-users@...r.kernel.org, linux-trace-devel@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V4 02/19] trace/osnoise: Split workload start from the
 tracer start

On 10/23/21 04:25, Steven Rostedt wrote:
> On Thu, 21 Oct 2021 14:56:40 +0200
> Daniel Bristot de Oliveira <bristot@...nel.org> wrote:
> 
>> +/*
>> + * osnoise_workload_stop - stop the workload and unhook the events
>> + */
>> +static void osnoise_workload_stop(void)
>> +{
>> +	if (!osnoise_busy)
>> +		return;
>> +
>> +	trace_osnoise_callback_enabled = false;
> 
> I know this is just moving this code, but the original code had this
> issue too, but there should be a comment here to why we need the
> compiler barrier.

I will add a comment, like we have on hwlat.

-- Daniel

> -- Steve
> 
> 
>> +	barrier();
>> +
>> +	stop_per_cpu_kthreads();
>> +
>> +	unhook_irq_events();
>> +	unhook_softirq_events();
>> +	unhook_thread_events();
>> +
>> +	osnoise_busy = false;
>> +}
>> +