linux-kernel - Re: [PATCH 2/4] locking/mutex: Clean up mutex.h

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Date: Wed, 21 Feb 2024 20:33:32 -0800
From: Boqun Feng <boqun.feng@...il.com>
To: Waiman Long <longman@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
	Will Deacon <will@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org,
	George Stark <gnstark@...utedevices.com>
Subject: Re: [PATCH 2/4] locking/mutex: Clean up mutex.h

On Mon, Feb 12, 2024 at 10:16:54PM -0500, Waiman Long wrote:
> CONFIG_DEBUG_MUTEXES and CONFIG_PREEMPT_RT are mutually exclusive. They
> can't be both set at the same time.  Move down the mutex_destroy()
> function declaration to the bottom of mutex.h to eliminate duplicated
> mutex_destroy() declaration.
> 
> Also remove the duplicated mutex_trylock() function declaration in the
> CONFIG_PREEMPT_RT section.
> 
> Signed-off-by: Waiman Long <longman@...hat.com>

Reviewed-by: Boqun Feng <boqun.feng@...il.com>

Although, can you move the first "#ifdef CONFIG_DEBUG_MUTEXES" out of
the "#ifndef CONFIG_PREEMPT_RT" and combine it with the second one, i.e.

	#ifdef CONFIG_DEBUG_MUTEXES
	# define __DEBUG_MUTEX_INITIALIZER(lockname) ...
	extern void mutex_destroy(struct mutex *lock);
	#else
	# define __DEBUG_MUTEX_INITIALIZER(lockname) ..
	static inline void mutex_destroy(struct mutex *lock) {}
	#endif

	#ifndef CONFIG_PREEMPT_RT
	...

Thoughts?

Regards,
Boqun

> ---
>  include/linux/mutex.h | 23 +++++++++++------------
>  1 file changed, 11 insertions(+), 12 deletions(-)
> 
> diff --git a/include/linux/mutex.h b/include/linux/mutex.h
> index 7e208d46ba5b..bad383713db2 100644
> --- a/include/linux/mutex.h
> +++ b/include/linux/mutex.h
> @@ -35,18 +35,10 @@
>  #ifndef CONFIG_PREEMPT_RT
>  
>  #ifdef CONFIG_DEBUG_MUTEXES
> -
> -#define __DEBUG_MUTEX_INITIALIZER(lockname)				\
> +# define __DEBUG_MUTEX_INITIALIZER(lockname)				\
>  	, .magic = &lockname
> -
> -extern void mutex_destroy(struct mutex *lock);
> -
>  #else
> -
>  # define __DEBUG_MUTEX_INITIALIZER(lockname)
> -
> -static inline void mutex_destroy(struct mutex *lock) {}
> -
>  #endif
>  
>  /**
> @@ -101,9 +93,6 @@ extern bool mutex_is_locked(struct mutex *lock);
>  
>  extern void __mutex_rt_init(struct mutex *lock, const char *name,
>  			    struct lock_class_key *key);
> -extern int mutex_trylock(struct mutex *lock);
> -
> -static inline void mutex_destroy(struct mutex *lock) { }
>  
>  #define mutex_is_locked(l)	rt_mutex_base_is_locked(&(l)->rtmutex)
>  
> @@ -170,6 +159,16 @@ extern void mutex_unlock(struct mutex *lock);
>  
>  extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock);
>  
> +#ifdef CONFIG_DEBUG_MUTEXES
> +
> +extern void mutex_destroy(struct mutex *lock);
> +
> +#else
> +
> +static inline void mutex_destroy(struct mutex *lock) {}
> +
> +#endif
> +
>  DEFINE_GUARD(mutex, struct mutex *, mutex_lock(_T), mutex_unlock(_T))
>  DEFINE_GUARD_COND(mutex, _try, mutex_trylock(_T))
>  DEFINE_GUARD_COND(mutex, _intr, mutex_lock_interruptible(_T) == 0)
> -- 
> 2.39.3
>