On Wed, Aug 25, 2021 at 07:06:13PM +0200, Eugene Syromiatnikov wrote:
> Commit 7ac592aa35a684ff ("sched: prctl() core-scheduling interface")
> made use of enum pid_type in prctl's arg4; this type and the associated
> enumeration definitions are not exposed to userspace. Christian
> has suggested to provide additional macro definitions that convey
> the meaning of the type argument more in alignment with its actual
> usage, and this patch does exactly that.
>
> Suggested-by: Christian Brauner <christian.brauner@xxxxxxxxxx>
> Complements: 7ac592aa35a684ff ("sched: prctl() core-scheduling interface")
> Signed-off-by: Eugene Syromiatnikov <esyr@xxxxxxxxxx>
> ---
I mean, I proposed the names so I'm ok with them. :)
Acked-by: Christian Brauner <christian.brauner@xxxxxxxxxx>
Peter et al. are you ok with this and do the names make sense to you?
Christian
> v4:
> - Rewritten in accordance with Christian Brauner's suggestion to provide
> macro definitions that are explicitly tailored for the prctl op.
>
> v3: https://lore.kernel.org/lkml/20210807120905.GA14706@xxxxxxxxxxxxxxxxx/
> - Fixed header guard macro: s/_UAPI_LINUX_PID_H/_UAPI_LINUX_PIDTYPE_H/,
> as noted by Dmitry Levin.
>
> v2: https://lore.kernel.org/lkml/20210807104800.GA22620@xxxxxxxxxxxxxxxxx/
> - Header file is renamed from pid.h to pidtype.h to avoid collisions
> with include/linux/pid.h when included from uapi headers;
> - The enum type has renamed from __kernel_pid_type to __kernel_pidtype
> to avoid possible confusion with __kernel_pid_t.
>
> v1: https://lore.kernel.org/lkml/20210807010123.GA5174@xxxxxxxxxxxxxxxxx/
> ---
> Documentation/admin-guide/hw-vuln/core-scheduling.rst | 5 +++--
> include/uapi/linux/prctl.h | 3 +++
> kernel/sched/core_sched.c | 4 ++++
> 3 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/admin-guide/hw-vuln/core-scheduling.rst b/Documentation/admin-guide/hw-vuln/core-scheduling.rst
> index 7b410ae..9a65fed 100644
> --- a/Documentation/admin-guide/hw-vuln/core-scheduling.rst
> +++ b/Documentation/admin-guide/hw-vuln/core-scheduling.rst
> @@ -61,8 +61,9 @@ arg3:
> ``pid`` of the task for which the operation applies.
>
> arg4:
> - ``pid_type`` for which the operation applies. It is of type ``enum pid_type``.
> - For example, if arg4 is ``PIDTYPE_TGID``, then the operation of this command
> + ``pid_type`` for which the operation applies. It is one of
> + ``PR_SCHED_CORE_SCOPE_``-prefixed macro constants. For example, if arg4
> + is ``PR_SCHED_CORE_SCOPE_THREAD_GROUP``, then the operation of this command
> will be performed for all tasks in the task group of ``pid``.
>
> arg5:
> diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
> index 967d9c5..644a3b4 100644
> --- a/include/uapi/linux/prctl.h
> +++ b/include/uapi/linux/prctl.h
> @@ -266,5 +266,8 @@ struct prctl_mm_map {
> # define PR_SCHED_CORE_SHARE_TO 2 /* push core_sched cookie to pid */
> # define PR_SCHED_CORE_SHARE_FROM 3 /* pull core_sched cookie to pid */
> # define PR_SCHED_CORE_MAX 4
> +# define PR_SCHED_CORE_SCOPE_THREAD 0
> +# define PR_SCHED_CORE_SCOPE_THREAD_GROUP 1
> +# define PR_SCHED_CORE_SCOPE_PROCESS_GROUP 2
>
> #endif /* _LINUX_PRCTL_H */
> diff --git a/kernel/sched/core_sched.c b/kernel/sched/core_sched.c
> index 9a80e9a..20f6409 100644
> --- a/kernel/sched/core_sched.c
> +++ b/kernel/sched/core_sched.c
> @@ -134,6 +134,10 @@ int sched_core_share_pid(unsigned int cmd, pid_t pid, enum pid_type type,
> if (!static_branch_likely(&sched_smt_present))
> return -ENODEV;
>
> + BUILD_BUG_ON(PR_SCHED_CORE_SCOPE_THREAD != PIDTYPE_PID);
> + BUILD_BUG_ON(PR_SCHED_CORE_SCOPE_THREAD_GROUP != PIDTYPE_TGID);
> + BUILD_BUG_ON(PR_SCHED_CORE_SCOPE_PROCESS_GROUP != PIDTYPE_PGID);
> +
> if (type > PIDTYPE_PGID || cmd >= PR_SCHED_CORE_MAX || pid < 0 ||
> (cmd != PR_SCHED_CORE_GET && uaddr))
> return -EINVAL;
> --
> 2.1.4
>
