Re: [PATCH 2/4] file: declare the FD_PREPARE() variable with __cleanup() directly

[David Laight]

On Thu, 17 Sep 2026 11:09:43 +0200
Christian Brauner <brauner@xxxxxxxxxx> wrote:

> The whole CLASS_INIT() detour isn't needed. Use __cleanup() directly and
> give the destructor a private name.

It also makes the code enormously easier to read.

David

> 
> No functional changes.
> 
> Signed-off-by: Christian Brauner (Amutable) <brauner@xxxxxxxxxx>
> ---
>  include/linux/file.h | 9 +++------
>  1 file changed, 3 insertions(+), 6 deletions(-)
> 
> diff --git a/include/linux/file.h b/include/linux/file.h
> index 2b864f457211..926cc58d0b7f 100644
> --- a/include/linux/file.h
> +++ b/include/linux/file.h
> @@ -146,9 +146,6 @@ struct fd_prepare {
>  	struct file *__file; /* do not access directly */
>  };
>  
> -/* Typedef for fd_prepare cleanup guards. */
> -typedef struct fd_prepare class_fd_prepare_t;
> -
>  /*
>   * Accessors for fd_prepare class members.
>   * _Generic() is used for zero-cost type safety.
> @@ -160,7 +157,7 @@ typedef struct fd_prepare class_fd_prepare_t;
>  	(_Generic((_fdf), struct fd_prepare: (_fdf).__file))
>  
>  /* Do not use directly. */
> -static __always_inline void class_fd_prepare_destructor(const struct fd_prepare *fdf)
> +static __always_inline void __fd_prepare_cleanup(const struct fd_prepare *fdf)
>  {
>  	if (unlikely(fdf->__fd >= 0)) {
>  		put_unused_fd(fdf->__fd);
> @@ -199,10 +196,10 @@ static __always_inline struct fd_prepare __fd_prepare(int fd, struct file *file)
>   * @_file_owned: struct file to take ownership of (can be expression)
>   */
>  #define FD_PREPARE(_fdf, _fd_flags, _file_owned)			\
> -	CLASS_INIT(fd_prepare, _fdf, ({					\
> +	struct fd_prepare _fdf __cleanup(__fd_prepare_cleanup) = ({	\
>  		int __fd = get_unused_fd_flags(_fd_flags);		\
>  		__fd_prepare(__fd, __fd < 0 ? NULL : (_file_owned));	\
> -	}))
> +	})
>  
>  /* Do not use directly. */
>  static __always_inline int __fd_publish(struct fd_prepare *fdf)
>