Re: [PATCH] sched: Consider task_struct::saved_state in wait_task_inactive().

[Peter Zijlstra]

On Fri, Feb 17, 2023 at 03:53:02PM +0100, Sebastian Andrzej Siewior wrote:
> wait_task_inactive() waits for thread to unschedule in a certain task state.
> On PREEMPT_RT that state may be stored in task_struct::saved_state while the
> thread, that is being waited for, blocks on a sleeping lock and
> task_struct::__state is set to TASK_RTLOCK_WAIT.
> It is not possible to check only for TASK_RTLOCK_WAIT to be sure that the task
> is blocked on a sleeping lock because during wake up (after the sleeping lock
> has been acquired) the task state is set TASK_RUNNING. After the task in on CPU
> and acquired the pi_lock it will reset the state accordingly but until then
> TASK_RUNNING will be observed (with the desired state is saved in saved_state).
> 
> Check also for task_struct::saved_state if the desired match was not found in
> task_struct::__state on PREEMPT_RT. If the state was found in saved_state, wait
> until the task is idle and state is visible in task_struct::__state.
> 
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
> Reviewed-by: Valentin Schneider <vschneid@xxxxxxxxxx>
> ---

Which if the very few wait_task_inactive() users requires this?