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

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Date: Thu, 22 Feb 2024 09:05:54 -0500
From: Waiman Long <longman@...hat.com>
To: Boqun Feng <boqun.feng@...il.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 2/21/24 23:33, Boqun Feng wrote:
> 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?

Sure. I can move it up and combine the two pieces.

Thanks for the review.

Cheers,
Longman

>
> 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
>>