Re: [RFC PATCH v3 01/10] rcuwait: Split type definition to its own header

[Peter Zijlstra]

On Thu, Jul 11, 2024 at 02:59:55PM +0200, Valentin Schneider wrote:
> A later commit will add a struct irq_work member to struct task_struct, which
> would require <linux/sched.h> to include the definition of struct
> irq_work.
> 
> Thanks to header dependency hell, incudling <linux/irq_work.h> in <linux/sched.h>
> results in defining inline helpers using not-yet-defined fields (mm_struct,
> task_struct, various task states...).
> 
> Break off the definition of struct rcuwait into its own header file.
> 
> Signed-off-by: Valentin Schneider <vschneid@xxxxxxxxxx>
> ---
>  include/linux/rcuwait.h       |  9 ++-------
>  include/linux/rcuwait_types.h | 16 ++++++++++++++++
>  2 files changed, 18 insertions(+), 7 deletions(-)
>  create mode 100644 include/linux/rcuwait_types.h
> 
> diff --git a/include/linux/rcuwait.h b/include/linux/rcuwait.h
> index 27343424225cf..1f1ca7d38cdf8 100644
> --- a/include/linux/rcuwait.h
> +++ b/include/linux/rcuwait.h
> @@ -5,17 +5,12 @@
>  #include <linux/rcupdate.h>
>  #include <linux/sched/signal.h>
>  
> +#include <linux/rcuwait_types.h>
> +
>  /*
>   * rcuwait provides a way of blocking and waking up a single
>   * task in an rcu-safe manner.
> - *
> - * The only time @task is non-nil is when a user is blocked (or
> - * checking if it needs to) on a condition, and reset as soon as we
> - * know that the condition has succeeded and are awoken.
>   */
> -struct rcuwait {
> -	struct task_struct __rcu *task;
> -};
>  
>  #define __RCUWAIT_INITIALIZER(name)		\
>  	{ .task = NULL, }
> diff --git a/include/linux/rcuwait_types.h b/include/linux/rcuwait_types.h
> new file mode 100644
> index 0000000000000..60a4385a2c368
> --- /dev/null
> +++ b/include/linux/rcuwait_types.h
> @@ -0,0 +1,16 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _LINUX_RCUWAIT_TYPES_H_
> +#define _LINUX_RCUWAIT_TYPES_H_
> +
> +#include <linux/sched.h>
> +
> +/*
> + * The only time @task is non-nil is when a user is blocked (or
> + * checking if it needs to) on a condition, and reset as soon as we
> + * know that the condition has succeeded and are awoken.
> + */
> +struct rcuwait {
> +	struct task_struct __rcu *task;
> +};
> +
> +#endif

Can't we simplu stick this in include/linux/types.h ?