tracing: Fix hwlat kthread migration

The hwlat tracer creates a kernel thread at start of the tracer. It is
pinned to a single CPU and will move to the next CPU after each period of
running. If the user modifies the migration thread's affinity, it will not
change after that happens.

The original code created the thread at the first instance it was called,
but later was changed to destroy the thread after the tracer was finished,
and would not be created until the next instance of the tracer was
established. The code that initialized the affinity was only called on the
initial instantiation of the tracer. After that, it was not initialized, and
the previous affinity did not match the current newly created one, making
it appear that the user modified the thread's affinity when it did not, and
the thread failed to migrate again.

Cc: stable@vger.kernel.org
Fixes: 0330f7aa8ee6 ("tracing: Have hwlat trace migrate across tracing_cpumask CPUs")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

path: root/include/soc/imx/cpuidle.h

/*
 * Copyright 2016 Pengutronix, <kernel@pengutronix.de>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 */

#ifndef __SOC_IMX_CPUIDLE_H__
#define __SOC_IMX_CPUIDLE_H__

#if defined(CONFIG_CPU_IDLE) && defined(CONFIG_SOC_IMX6Q)
void imx6q_cpuidle_fec_irqs_used(void);
void imx6q_cpuidle_fec_irqs_unused(void);
#else
static inline void imx6q_cpuidle_fec_irqs_used(void) { }
static inline void imx6q_cpuidle_fec_irqs_unused(void) { }
#endif

#endif /* __SOC_IMX_CPUIDLE_H__ */