linux-kernel - Re: [PATCH] trace: Do some cleanups for osnoise tracer

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Message-ID: <20210913105800.77699437@oasis.local.home>
Date:   Mon, 13 Sep 2021 10:58:00 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Tang Yizhou <tangyizhou@...wei.com>
Cc:     <bristot@...hat.com>, <mingo@...hat.com>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] trace: Do some cleanups for osnoise tracer

On Mon, 13 Sep 2021 11:32:06 +0800
Tang Yizhou <tangyizhou@...wei.com> wrote:

> 1. Add 'static' and 'const' qualifier when necessary.
> 2. Use DEFINE_MUTEX() to define a mutex.
> 
> Signed-off-by: Tang Yizhou <tangyizhou@...wei.com>
> ---
>  kernel/trace/trace_osnoise.c | 12 +++++-------
>  1 file changed, 5 insertions(+), 7 deletions(-)
> 
> diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c
> index ce053619f289..c1a8dc6a154e 100644
> --- a/kernel/trace/trace_osnoise.c
> +++ b/kernel/trace/trace_osnoise.c
> @@ -105,7 +105,7 @@ struct osnoise_variables {
>  /*
>   * Per-cpu runtime information.
>   */
> -DEFINE_PER_CPU(struct osnoise_variables, per_cpu_osnoise_var);
> +static DEFINE_PER_CPU(struct osnoise_variables, per_cpu_osnoise_var);
>  
>  /*
>   * this_cpu_osn_var - Return the per-cpu osnoise_variables on its relative CPU
> @@ -128,7 +128,7 @@ struct timerlat_variables {
>  	u64			count;
>  };
>  
> -DEFINE_PER_CPU(struct timerlat_variables, per_cpu_timerlat_var);
> +static DEFINE_PER_CPU(struct timerlat_variables, per_cpu_timerlat_var);
>  
>  /*
>   * this_cpu_tmr_var - Return the per-cpu timerlat_variables on its relative CPU
> @@ -220,7 +220,7 @@ struct timerlat_sample {
>  /*
>   * Protect the interface.
>   */
> -struct mutex interface_lock;
> +static DEFINE_MUTEX(interface_lock);
>  
>  /*
>   * Tracer data.
> @@ -1818,8 +1818,8 @@ static struct trace_min_max_param osnoise_print_stack = {
>  /*
>   * osnoise/timerlat_period: min 100 us, max 1 s
>   */
> -u64 timerlat_min_period = 100;
> -u64 timerlat_max_period = 1000000;
> +static const u64 timerlat_min_period = 100;
> +static const u64 timerlat_max_period = 1000000;

Can't be const because it can be modified.

-- Steve

>  static struct trace_min_max_param timerlat_period = {
>  	.lock	= &interface_lock,
>  	.val	= &osnoise_data.timerlat_period,
> @@ -2087,8 +2087,6 @@ __init static int init_osnoise_tracer(void)
>  {
>  	int ret;
>  
> -	mutex_init(&interface_lock);
> -
>  	cpumask_copy(&osnoise_cpumask, cpu_all_mask);
>  
>  	ret = register_tracer(&osnoise_tracer);