Re: [PATCH] powerpc/xmon: fix task state output

[Michael Ellerman <mpe@ellerman.id.au>]

Denis Kirjanov <kda@linux-powerpc.org> writes:
> p_state is unsigned since the commit 2f064a59a11f
>
> The patch also uses TASK_RUNNING instead of null.
>
> Fixes: 2f064a59a11f ("sched: Change task_struct::state")
> Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org>
> ---
>  arch/powerpc/xmon/xmon.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
> index dd8241c009e5..8b28ff9d98d1 100644
> --- a/arch/powerpc/xmon/xmon.c
> +++ b/arch/powerpc/xmon/xmon.c
> @@ -3264,8 +3264,7 @@ static void show_task(struct task_struct *volatile tsk)
>  	 * appropriate for calling from xmon. This could be moved
>  	 * to a common, generic, routine used by both.
>  	 */
> -	state = (p_state == 0) ? 'R' :
> -		(p_state < 0) ? 'U' :

I guess 'U' meant 'unknown'? I always thought it meant uninterruptible,
but obviously that is 'D'.

> +	state = (p_state == TASK_RUNNING) ? 'R' :
>  		(p_state & TASK_UNINTERRUPTIBLE) ? 'D' :
>  		(p_state & TASK_STOPPED) ? 'T' :
>  		(p_state & TASK_TRACED) ? 'C' :

I think a better cleanup would be to use task_is_running(),
task_is_traced(), task_is_stopped(). That way we're insulated somewhat
from any future changes.

That would add additional READ_ONCE()s of the state, but I don't think
we care, the task should not be running if the system is in xmon.

cheers