linux-kernel - Re: [PATCH] tracing/osnoise: Fix notify new tracing_max

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Date:   Tue, 28 Mar 2023 19:16:13 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Daniel Bristot de Oliveira <bristot@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
        Masami Hiramatsu <mhiramat@...nel.org>
Subject: Re: [PATCH] tracing/osnoise: Fix notify new tracing_max_latency

On Fri, 24 Mar 2023 18:51:35 +0100
Daniel Bristot de Oliveira <bristot@...nel.org> wrote:

> timerlat is not reporting a new tracing_max_latency for the thread
> latency. Also, the tracer is reporting new max latency on instances
> where the tracing is off, creating inconsistencies between the max
> reported values in the trace and in the tracing_max_latency. Thus
> only report new tracing_max_latency on active tracing instances.

Sounds to me this patch fixes two different bugs. If so, can you please
break it up into two different patches?

Thanks!

-- Steve

> 
> Fixes: dae181349f1e ("tracing/osnoise: Support a list of trace_array *tr")
> Cc: Daniel Bristot de Oliveira <bristot@...nel.org>
> Cc: Steven Rostedt <rostedt@...dmis.org>
> Cc: Masami Hiramatsu <mhiramat@...nel.org>
> Signed-off-by: Daniel Bristot de Oliveira <bristot@...nel.org>
> ---
>  kernel/trace/trace_osnoise.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c
> index 210e1f168392..2a1b337ac643 100644
> --- a/kernel/trace/trace_osnoise.c
> +++ b/kernel/trace/trace_osnoise.c
> @@ -1296,7 +1296,7 @@ static void notify_new_max_latency(u64 latency)
>  	rcu_read_lock();
>  	list_for_each_entry_rcu(inst, &osnoise_instances, list) {
>  		tr = inst->tr;
> -		if (tr->max_latency < latency) {
> +		if (tracer_tracing_is_on(tr) && tr->max_latency < latency) {
>  			tr->max_latency = latency;
>  			latency_fsnotify(tr);
>  		}
> @@ -1738,6 +1738,8 @@ static int timerlat_main(void *data)
>  
>  		trace_timerlat_sample(&s);
>  
> +		notify_new_max_latency(diff);
> +
>  		timerlat_dump_stack(time_to_us(diff));
>  
>  		tlat->tracing_thread = false;