linux-kernel - Re: [PATCH] lockdep: make class_filter() inline and remove unnecessary macros

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Message-ID: <ZrEOVOA3e5Dl6l_2@tardis>
Date: Mon, 5 Aug 2024 10:39:39 -0700
From: Boqun Feng <boqun.feng@...il.com>
To: Wenchao Hao <haowenchao22@...il.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
	Will Deacon <will@...nel.org>, Waiman Long <longman@...hat.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] lockdep: make class_filter() inline and remove
 unnecessary macros

On Thu, Jun 06, 2024 at 04:57:44PM +0800, Wenchao Hao wrote:
> This is just a clean code which simplify the code implement and make it
> easy to understand. No logic changed from origin implement.
> 
> Make class_filter() inline which just return 0, and directly called from
> verbose(), very_verbose(), HARDIRQ_verbose() and SOFTIRQ_verbose() without
> macro control, remove unnecessary macros VERY_VERBOSE, HARDIRQ_VERBOSE
> and SOFTIRQ_VERBOSE.
> 

Are you looking into using a Kconfig to control the behavior of
class_filter()? Otherwise, I find this change is not that necessary,
don't make me wrong, it's better than the current version, but still it
just changes one version of dead code into another, so doesn't bring
anything.

Regards,
BOqun

> Signed-off-by: Wenchao Hao <haowenchao22@...il.com>
> ---
>  kernel/locking/lockdep.c | 25 +------------------------
>  1 file changed, 1 insertion(+), 24 deletions(-)
> 
> diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
> index 151bd3de5936..cd8356106da2 100644
> --- a/kernel/locking/lockdep.c
> +++ b/kernel/locking/lockdep.c
> @@ -478,21 +478,11 @@ void lockdep_set_selftest_task(struct task_struct *task)
>   */
>  
>  #define VERBOSE			0
> -#define VERY_VERBOSE		0
>  
> -#if VERBOSE
> -# define HARDIRQ_VERBOSE	1
> -# define SOFTIRQ_VERBOSE	1
> -#else
> -# define HARDIRQ_VERBOSE	0
> -# define SOFTIRQ_VERBOSE	0
> -#endif
> -
> -#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
>  /*
>   * Quick filtering for interesting events:
>   */
> -static int class_filter(struct lock_class *class)
> +static inline int class_filter(struct lock_class *class)
>  {
>  #if 0
>  	/* Example */
> @@ -506,14 +496,10 @@ static int class_filter(struct lock_class *class)
>  	/* Filter everything else. 1 would be to allow everything else */
>  	return 0;
>  }
> -#endif
>  
>  static int verbose(struct lock_class *class)
>  {
> -#if VERBOSE
>  	return class_filter(class);
> -#endif
> -	return 0;
>  }
>  
>  static void print_lockdep_off(const char *bug_msg)
> @@ -809,10 +795,7 @@ static void print_kernel_ident(void)
>  
>  static int very_verbose(struct lock_class *class)
>  {
> -#if VERY_VERBOSE
>  	return class_filter(class);
> -#endif
> -	return 0;
>  }
>  
>  /*
> @@ -4171,18 +4154,12 @@ void print_irqtrace_events(struct task_struct *curr)
>  
>  static int HARDIRQ_verbose(struct lock_class *class)
>  {
> -#if HARDIRQ_VERBOSE
>  	return class_filter(class);
> -#endif
> -	return 0;
>  }
>  
>  static int SOFTIRQ_verbose(struct lock_class *class)
>  {
> -#if SOFTIRQ_VERBOSE
>  	return class_filter(class);
> -#endif
> -	return 0;
>  }
>  
>  static int (*state_verbose_f[])(struct lock_class *class) = {
> -- 
> 2.38.1
>