linux-kernel - Re: [PATCH v1 03/12] PM: sleep: stats: Use array of suspend step names

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Message-ID: <ZbIQs2R0ybg/54Zy@linux.intel.com>
Date: Thu, 25 Jan 2024 08:41:39 +0100
From: Stanislaw Gruszka <stanislaw.gruszka@...ux.intel.com>
To: "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc: Linux PM <linux-pm@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Ulf Hansson <ulf.hansson@...aro.org>
Subject: Re: [PATCH v1 03/12] PM: sleep: stats: Use array of suspend step
 names

On Mon, Jan 22, 2024 at 12:25:45PM +0100, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> Replace suspend_step_name() in the suspend statistics code with an array
> of suspend step names which has fewer lines of code and less overhead.
> 
> While at it, remove two unnecessary line breaks in suspend_stats_show()
> for a more consistent code layout.
> 
> No intentional functional impact.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Reviewed-by: Stanislaw Gruszka <stanislaw.gruszka@...ux.intel.com>

> ---
>  include/linux/suspend.h |    3 ++-
>  kernel/power/main.c     |   48 +++++++++++++++++-------------------------------
>  2 files changed, 19 insertions(+), 32 deletions(-)
> 
> Index: linux-pm/include/linux/suspend.h
> ===================================================================
> --- linux-pm.orig/include/linux/suspend.h
> +++ linux-pm/include/linux/suspend.h
> @@ -41,7 +41,8 @@ typedef int __bitwise suspend_state_t;
>  #define PM_SUSPEND_MAX		((__force suspend_state_t) 4)
>  
>  enum suspend_stat_step {
> -	SUSPEND_FREEZE = 1,
> +	SUSPEND_NONE = 0,
> +	SUSPEND_FREEZE,
>  	SUSPEND_PREPARE,
>  	SUSPEND_SUSPEND,
>  	SUSPEND_SUSPEND_LATE,
> Index: linux-pm/kernel/power/main.c
> ===================================================================
> --- linux-pm.orig/kernel/power/main.c
> +++ linux-pm/kernel/power/main.c
> @@ -319,25 +319,17 @@ static ssize_t pm_test_store(struct kobj
>  power_attr(pm_test);
>  #endif /* CONFIG_PM_SLEEP_DEBUG */
>  
> -static char *suspend_step_name(enum suspend_stat_step step)
> -{
> -	switch (step) {
> -	case SUSPEND_FREEZE:
> -		return "freeze";
> -	case SUSPEND_PREPARE:
> -		return "prepare";
> -	case SUSPEND_SUSPEND:
> -		return "suspend";
> -	case SUSPEND_SUSPEND_NOIRQ:
> -		return "suspend_noirq";
> -	case SUSPEND_RESUME_NOIRQ:
> -		return "resume_noirq";
> -	case SUSPEND_RESUME:
> -		return "resume";
> -	default:
> -		return "";
> -	}
> -}
> +static const char * const suspend_step_names[] = {
> +	[SUSPEND_NONE] = "",
> +	[SUSPEND_FREEZE] = "freeze",
> +	[SUSPEND_PREPARE] = "prepare",
> +	[SUSPEND_SUSPEND] = "suspend",
> +	[SUSPEND_SUSPEND_LATE] = "suspend_late",
> +	[SUSPEND_SUSPEND_NOIRQ] = "suspend_noirq",
> +	[SUSPEND_RESUME_NOIRQ] = "resume_noirq",
> +	[SUSPEND_RESUME_EARLY] = "resume_early",
> +	[SUSPEND_RESUME] = "resume",
> +};
>  
>  #define suspend_attr(_name, format_str)				\
>  static ssize_t _name##_show(struct kobject *kobj,		\
> @@ -392,16 +384,14 @@ static struct kobj_attribute last_failed
>  static ssize_t last_failed_step_show(struct kobject *kobj,
>  		struct kobj_attribute *attr, char *buf)
>  {
> -	int index;
>  	enum suspend_stat_step step;
> -	char *last_failed_step = NULL;
> +	int index;
>  
>  	index = suspend_stats.last_failed_step + REC_FAILED_NUM - 1;
>  	index %= REC_FAILED_NUM;
>  	step = suspend_stats.failed_steps[index];
> -	last_failed_step = suspend_step_name(step);
>  
> -	return sprintf(buf, "%s\n", last_failed_step);
> +	return sprintf(buf, "%s\n", suspend_step_names[step]);
>  }
>  static struct kobj_attribute last_failed_step = __ATTR_RO(last_failed_step);
>  
> @@ -477,26 +467,22 @@ static int suspend_stats_show(struct seq
>  	for (i = 1; i < REC_FAILED_NUM; i++) {
>  		index = last_dev + REC_FAILED_NUM - i;
>  		index %= REC_FAILED_NUM;
> -		seq_printf(s, "\t\t\t%-s\n",
> -			suspend_stats.failed_devs[index]);
> +		seq_printf(s, "\t\t\t%-s\n", suspend_stats.failed_devs[index]);
>  	}
>  	seq_printf(s,	"  last_failed_errno:\t%-d\n",
>  			suspend_stats.errno[last_errno]);
>  	for (i = 1; i < REC_FAILED_NUM; i++) {
>  		index = last_errno + REC_FAILED_NUM - i;
>  		index %= REC_FAILED_NUM;
> -		seq_printf(s, "\t\t\t%-d\n",
> -			suspend_stats.errno[index]);
> +		seq_printf(s, "\t\t\t%-d\n", suspend_stats.errno[index]);
>  	}
>  	seq_printf(s,	"  last_failed_step:\t%-s\n",
> -			suspend_step_name(
> -				suspend_stats.failed_steps[last_step]));
> +		   suspend_step_names[suspend_stats.failed_steps[last_step]]);
>  	for (i = 1; i < REC_FAILED_NUM; i++) {
>  		index = last_step + REC_FAILED_NUM - i;
>  		index %= REC_FAILED_NUM;
>  		seq_printf(s, "\t\t\t%-s\n",
> -			suspend_step_name(
> -				suspend_stats.failed_steps[index]));
> +			   suspend_step_names[suspend_stats.failed_steps[index]]);
>  	}
>  
>  	return 0;
> 
> 
>