Re: [PATCH v2 06/11] uapi/fcntl: mark range as reserved

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On Tue 24-06-25 10:29:09, Christian Brauner wrote:
> Mark the range from -10000 to -40000 as a range reserved for special
> in-kernel values. Move the PIDFD_SELF_*/PIDFD_THREAD_* sentinels over so
> all the special values are in one place.
> 
> Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@xxxxxxx>

								Honza

> ---
>  include/uapi/linux/fcntl.h            | 16 ++++++++++++++++
>  include/uapi/linux/pidfd.h            | 15 ---------------
>  tools/testing/selftests/pidfd/pidfd.h |  2 +-
>  3 files changed, 17 insertions(+), 16 deletions(-)
> 
> diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h
> index a15ac2fa4b20..ba4a698d2f33 100644
> --- a/include/uapi/linux/fcntl.h
> +++ b/include/uapi/linux/fcntl.h
> @@ -90,10 +90,26 @@
>  #define DN_ATTRIB	0x00000020	/* File changed attibutes */
>  #define DN_MULTISHOT	0x80000000	/* Don't remove notifier */
>  
> +/* Reserved kernel ranges [-100], [-10000, -40000]. */
>  #define AT_FDCWD		-100    /* Special value for dirfd used to
>  					   indicate openat should use the
>  					   current working directory. */
>  
> +/*
> + * The concept of process and threads in userland and the kernel is a confusing
> + * one - within the kernel every thread is a 'task' with its own individual PID,
> + * however from userland's point of view threads are grouped by a single PID,
> + * which is that of the 'thread group leader', typically the first thread
> + * spawned.
> + *
> + * To cut the Gideon knot, for internal kernel usage, we refer to
> + * PIDFD_SELF_THREAD to refer to the current thread (or task from a kernel
> + * perspective), and PIDFD_SELF_THREAD_GROUP to refer to the current thread
> + * group leader...
> + */
> +#define PIDFD_SELF_THREAD		-10000 /* Current thread. */
> +#define PIDFD_SELF_THREAD_GROUP		-10001 /* Current thread group leader. */
> +
>  
>  /* Generic flags for the *at(2) family of syscalls. */
>  
> diff --git a/include/uapi/linux/pidfd.h b/include/uapi/linux/pidfd.h
> index c27a4e238e4b..957db425d459 100644
> --- a/include/uapi/linux/pidfd.h
> +++ b/include/uapi/linux/pidfd.h
> @@ -42,21 +42,6 @@
>  #define PIDFD_COREDUMP_USER	(1U << 2) /* coredump was done as the user. */
>  #define PIDFD_COREDUMP_ROOT	(1U << 3) /* coredump was done as root. */
>  
> -/*
> - * The concept of process and threads in userland and the kernel is a confusing
> - * one - within the kernel every thread is a 'task' with its own individual PID,
> - * however from userland's point of view threads are grouped by a single PID,
> - * which is that of the 'thread group leader', typically the first thread
> - * spawned.
> - *
> - * To cut the Gideon knot, for internal kernel usage, we refer to
> - * PIDFD_SELF_THREAD to refer to the current thread (or task from a kernel
> - * perspective), and PIDFD_SELF_THREAD_GROUP to refer to the current thread
> - * group leader...
> - */
> -#define PIDFD_SELF_THREAD		-10000 /* Current thread. */
> -#define PIDFD_SELF_THREAD_GROUP		-20000 /* Current thread group leader. */
> -
>  /*
>   * ...and for userland we make life simpler - PIDFD_SELF refers to the current
>   * thread, PIDFD_SELF_PROCESS refers to the process thread group leader.
> diff --git a/tools/testing/selftests/pidfd/pidfd.h b/tools/testing/selftests/pidfd/pidfd.h
> index efd74063126e..5dfeb1bdf399 100644
> --- a/tools/testing/selftests/pidfd/pidfd.h
> +++ b/tools/testing/selftests/pidfd/pidfd.h
> @@ -56,7 +56,7 @@
>  #endif
>  
>  #ifndef PIDFD_SELF_THREAD_GROUP
> -#define PIDFD_SELF_THREAD_GROUP		-20000 /* Current thread group leader. */
> +#define PIDFD_SELF_THREAD_GROUP		-10001 /* Current thread group leader. */
>  #endif
>  
>  #ifndef PIDFD_SELF
> 
> -- 
> 2.47.2
> 
-- 
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR




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