Re: [PATCH v4 02/11] futex: Add basic infrastructure for local task local hash.

[Thomas Gleixner <tglx@linutronix.de>]

On Tue, Dec 03 2024 at 17:42, Sebastian Andrzej Siewior wrote:
>  long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
>  	      u32 __user *uaddr2, u32 val2, u32 val3);
> +int futex_hash_prctl(unsigned long arg2, unsigned long arg3,
> +		     unsigned long arg4, unsigned long arg5);
> +int futex_hash_allocate_default(void);
> +void futex_hash_free(struct mm_struct *mm);
> +
> +static inline void futex_mm_init(struct mm_struct *mm)
> +{
> +	mm->futex_hash_bucket = NULL;
> +}
> +
>  #else
>  static inline void futex_init_task(struct task_struct *tsk) { }
>  static inline void futex_exit_recursive(struct task_struct *tsk) { }
> @@ -88,6 +98,18 @@ static inline long do_futex(u32 __user *uaddr, int op, u32 val,
>  {
>  	return -EINVAL;
>  }
> +static inline int futex_hash_prctl(unsigned long arg2, unsigned long arg3,
> +				   unsigned long arg4, unsigned long arg5)
> +{
> +	return -EINVAL;
> +}
> +static inline int futex_hash_allocate_default(void)
> +{
> +	return 0;
> +}
> +static inline void futex_hash_free(struct mm_struct *mm) { }
> +static inline void futex_mm_init(struct mm_struct *mm) { }
> +
>  #endif
>  
>  #endif
> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> index 7361a8f3ab68e..b16b97ab8fb2a 100644
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -30,6 +30,7 @@
>  #define INIT_PASID	0
>  
>  struct address_space;
> +struct futex_hash_bucket;
>  struct mem_cgroup;
>  
>  /*
> @@ -902,6 +903,8 @@ struct mm_struct {
>  		int mm_lock_seq;
>  #endif
>  
> +		unsigned int			futex_hash_mask;
> +		struct futex_hash_bucket	*futex_hash_bucket;

So you provided stubs for the accessors/init functions etc. Shouldn't
this be #ifdef guarded too?

Thanks,

        tglx