On Thu, Jan 13, 2022 at 03:39:40PM -0800, Peter Oskolkov wrote:
> ---
> include/uapi/linux/umcg.h | 10 ++++++++++
> kernel/sched/umcg.c | 7 +++++--
> 2 files changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/include/uapi/linux/umcg.h b/include/uapi/linux/umcg.h
> index 93fccb44283b..a29e5e91a251 100644
> --- a/include/uapi/linux/umcg.h
> +++ b/include/uapi/linux/umcg.h
> @@ -148,4 +148,14 @@ enum umcg_ctl_flag {
> UMCG_CTL_WORKER = 0x10000,
> };
>
> +/**
> + * enum umcg_kick_flag - flags to pass to sys_umcg_kick
> + * @UMCG_KICK_RESCHED: reschedule the task; used for worker preemption
> + * @UMCG_KICK_TTWU: wake the task; used to wake servers
> + */
> +enum umcg_kick_flag {
> + UMCG_KICK_RESCHED = 0x001,
> + UMCG_KICK_TTWU = 0x002,
> +};
> +
> #endif /* _UAPI_LINUX_UMCG_H */
> diff --git a/kernel/sched/umcg.c b/kernel/sched/umcg.c
> index b85dec6b82e4..e33ec9eddc3e 100644
> --- a/kernel/sched/umcg.c
> +++ b/kernel/sched/umcg.c
> @@ -669,12 +669,15 @@ SYSCALL_DEFINE2(umcg_kick, u32, flags, pid_t, tid)
> if (!task)
> return -ESRCH;
>
> - if (flags)
> + if (flags != UMCG_KICK_RESCHED && flags != UMCG_KICK_TTWU)
> return -EINVAL;
>
> #ifdef CONFIG_SMP
> - smp_send_reschedule(task_cpu(task));
> + if (flags == UMCG_KICK_RESCHED)
> + smp_send_reschedule(task_cpu(task));
> #endif
> + if (flags == UMCG_KICK_TTWU)
> + try_to_wake_up(task, TASK_NORMAL, 0);
>
> return 0;
> }
I'm thinking the simpler thing is this..
(also note the task ref leak fixed)
--- a/kernel/sched/umcg.c
+++ b/kernel/sched/umcg.c
@@ -719,16 +719,22 @@ void umcg_notify_resume(struct pt_regs *
*/
SYSCALL_DEFINE2(umcg_kick, u32, flags, pid_t, tid)
{
- struct task_struct *task = umcg_get_task(tid);
- if (!task)
- return -ESRCH;
+ struct task_struct *task;
if (flags)
return -EINVAL;
+
+ task = umcg_get_task(tid);
+ if (!task)
+ return -ESRCH;
+ if (!try_to_wake_up(task, TASK_NORMAL, WF_CURRENT_CPU)) {
#ifdef CONFIG_SMP
- smp_send_reschedule(task_cpu(task));
+ smp_send_reschedule(task_cpu(task));
#endif
+ }
+
+ put_task_struct(task);
return 0;
}
