linux-kernel - [for-next][PATCH 04/14] tracing/osnoise: Use start/stop_per_cpu_kthreads() on osnoise_cpus

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Message-ID: <20211102201157.238668108@goodmis.org>
Date:   Tue, 02 Nov 2021 16:11:30 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org
Cc:     Ingo Molnar <mingo@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        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>,
        Daniel Bristot de Oliveira <bristot@...nel.org>,
        linux-rt-users@...r.kernel.org, linux-trace-devel@...r.kernel.org
Subject: [for-next][PATCH 04/14] tracing/osnoise: Use start/stop_per_cpu_kthreads() on
 osnoise_cpus_write()

From: Daniel Bristot de Oliveira <bristot@...nel.org>

When writing a new CPU mask via osnoise/cpus, if the tracer is running,
the workload is restarted to follow the new cpumask. The restart is
currently done using osnoise_workload_start/stop(), which disables the
workload *and* the instrumentation. However, disabling the
instrumentation is not necessary.

Calling start/stop_per_cpu_kthreads() is enough to apply the new
osnoise/cpus config.

Link: https://lkml.kernel.org/r/ee633e82867c5b88851aa6040522a799c0034486.1635702894.git.bristot@kernel.org

Cc: Ingo Molnar <mingo@...hat.com>
Cc: Tom Zanussi <zanussi@...nel.org>
Cc: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Juri Lelli <juri.lelli@...hat.com>
Cc: Clark Williams <williams@...hat.com>
Cc: John Kacur <jkacur@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc: Daniel Bristot de Oliveira <bristot@...nel.org>
Cc: linux-rt-users@...r.kernel.org
Cc: linux-trace-devel@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Signed-off-by: Daniel Bristot de Oliveira <bristot@...nel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
---
 kernel/trace/trace_osnoise.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c
index 5279a4990493..cacc11b7d5ae 100644
--- a/kernel/trace/trace_osnoise.c
+++ b/kernel/trace/trace_osnoise.c
@@ -1678,9 +1678,6 @@ osnoise_cpus_read(struct file *filp, char __user *ubuf, size_t count,
 	return count;
 }
 
-static int osnoise_workload_start(void);
-static void osnoise_workload_stop(void);
-
 /*
  * osnoise_cpus_write - Write function for "cpus" entry
  * @filp: The active open file structure
@@ -1725,7 +1722,7 @@ osnoise_cpus_write(struct file *filp, const char __user *ubuf, size_t count,
 	mutex_lock(&trace_types_lock);
 	running = osnoise_busy;
 	if (running)
-		osnoise_workload_stop();
+		stop_per_cpu_kthreads();
 
 	mutex_lock(&interface_lock);
 	/*
@@ -1739,7 +1736,7 @@ osnoise_cpus_write(struct file *filp, const char __user *ubuf, size_t count,
 	mutex_unlock(&interface_lock);
 
 	if (running)
-		osnoise_workload_start();
+		start_per_cpu_kthreads();
 	mutex_unlock(&trace_types_lock);
 
 	free_cpumask_var(osnoise_cpumask_new);
-- 
2.33.0