Re: [patch 2/8] futex: Move futex related mm_struct data into a struct

[Mathieu Desnoyers]

On 2026-03-16 13:13, Thomas Gleixner wrote:
> Having all these members in mm_struct along with the required #ifdeffery is
> annoying, does not allow efficient initializing of the data with
> memset() and makes extending it tedious.
>
> Move it into a data structure and fix up all usage sites.
>
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxx>
> ---
>   include/linux/futex_types.h |   22 +++++++
>   include/linux/mm_types.h    |   11 ---
>   kernel/futex/core.c         |  123 ++++++++++++++++++++------------------------
>   3 files changed, 80 insertions(+), 76 deletions(-)
>
> --- a/include/linux/futex_types.h
> +++ b/include/linux/futex_types.h
> @@ -31,4 +31,26 @@ struct futex_ctrl {
>   struct futex_ctrl { };
>   #endif /* !CONFIG_FUTEX */
>   
> +/**
> + * struct futex_mm_data - Futex related per MM data
> + * @phash_lock:		Mutex to protect the private hash operations
> + * @phash:		RCU managed pointer to the private hash
> + * @phash_new:		Pointer to a newly allocated private hash
> + * @phash_batches:	Batch state for RCU synchronization
> + * @phash_rcu:		RCU head for call_rcu()
> + * @phash_atomic:	Aggregate value for @phash_ref
> + * @phash_ref:		Per CPU reference counter for a private hash
> + */
> +struct futex_mm_data {
> +#ifdef CONFIG_FUTEX_PRIVATE_HASH
> +	struct mutex			phash_lock;
> +	struct futex_private_hash	__rcu *phash;
> +	struct futex_private_hash	*phash_new;
> +	unsigned long			phash_batches;
> +	struct rcu_head			phash_rcu;
> +	atomic_long_t			phash_atomic;
> +	unsigned int			__percpu *phash_ref;
> +#endif
> +};

In the previous patch you use the approach of declaring an empty
structure within the #else, and here the content of the struct is
conditional. Preferably pick one approach ?

Other than this minor nit:

Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>

--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com