Re: [PATCH v4 1/4] include/linux/suspend.h: Only show pm_pr_dbg messages at suspend/resume

[Randy Dunlap]

On 4/7/24 5:49 AM, xiongxin wrote:
> From: Mario Limonciello <mario.limonciello@xxxxxxx>
> 
> All uses in the kernel are currently already oriented around
> suspend/resume. As some other parts of the kernel may also use these
> messages in functions that could also be used outside of
> suspend/resume, only enable in suspend/resume path.
> 
> Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
> ---
> v3->v4:
>  * add back do/while as it wasn't pointless.  It fixes a warning.
> ---
>  include/linux/suspend.h | 8 +++++---
>  kernel/power/main.c     | 6 ++++++
>  2 files changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/include/linux/suspend.h b/include/linux/suspend.h
> index 1a0426e6761c..74f406c53ac0 100644
> --- a/include/linux/suspend.h
> +++ b/include/linux/suspend.h
> @@ -555,6 +555,7 @@ static inline void unlock_system_sleep(unsigned int flags) {}
>  #ifdef CONFIG_PM_SLEEP_DEBUG
>  extern bool pm_print_times_enabled;
>  extern bool pm_debug_messages_on;
> +extern bool pm_debug_messages_should_print(void);
>  static inline int pm_dyn_debug_messages_on(void)
>  {
>  #ifdef CONFIG_DYNAMIC_DEBUG
> @@ -568,14 +569,14 @@ static inline int pm_dyn_debug_messages_on(void)
>  #endif
>  #define __pm_pr_dbg(fmt, ...)					\
>  	do {							\
> -		if (pm_debug_messages_on)			\
> +		if (pm_debug_messages_should_print())		\
>  			printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__);	\
>  		else if (pm_dyn_debug_messages_on())		\
>  			pr_debug(fmt, ##__VA_ARGS__);	\
>  	} while (0)
>  #define __pm_deferred_pr_dbg(fmt, ...)				\
>  	do {							\
> -		if (pm_debug_messages_on)			\
> +		if (pm_debug_messages_should_print())		\
>  			printk_deferred(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__);	\
>  	} while (0)
>  #else
> @@ -593,7 +594,8 @@ static inline int pm_dyn_debug_messages_on(void)
>  /**
>   * pm_pr_dbg - print pm sleep debug messages
>   *
> - * If pm_debug_messages_on is enabled, print message.
> + * If pm_debug_messages_on is enabled and the system is entering/leaving
> + *      suspend, print message.
>   * If pm_debug_messages_on is disabled and CONFIG_DYNAMIC_DEBUG is enabled,
>   *	print message only from instances explicitly enabled on dynamic debug's
>   *	control.
> diff --git a/kernel/power/main.c b/kernel/power/main.c
> index 3113ec2f1db4..daa535012e51 100644
> --- a/kernel/power/main.c
> +++ b/kernel/power/main.c
> @@ -556,6 +556,12 @@ power_attr_ro(pm_wakeup_irq);
>  
>  bool pm_debug_messages_on __read_mostly;
>  
> +bool pm_debug_messages_should_print(void)
> +{
> +	return pm_debug_messages_on && pm_suspend_target_state != PM_SUSPEND_ON;
> 
>> hibernate processes also mostly use the pm_pr_dbg() function, which
>> results in hibernate processes only being able to output such logs
>> through dynamic debug, which is unfriendly to kernels without
>> CONFIG_DYNAMIC_DEBUG configuration.

This part of the patch doesn't look so good. ^^^^^^^^^^^^^^^^^^^^

> 
> +}
> +EXPORT_SYMBOL_GPL(pm_debug_messages_should_print);
> +
>  static ssize_t pm_debug_messages_show(struct kobject *kobj,
>  				      struct kobj_attribute *attr, char *buf)
>  {
> 

-- 
#Randy