Re: [PATCH] fix TASK_STOPPED vs TASK_NONINTERACTIVE interaction

[Coywolf Qi Hunt]

On 9/30/05, Linus Torvalds <torvalds@xxxxxxxx> wrote:
>
>
> On Thu, 29 Sep 2005, Oleg Nesterov wrote:
> >
> > do_signal_stop:
> >
> >       for_each_thread(t) {
> >               if (t->state < TASK_STOPPED)
> >                       ++sig->group_stop_count;
> >       }
> >
> > However, TASK_NONINTERACTIVE > TASK_STOPPED, so this loop will not
> > count TASK_INTERRUPTIBLE | TASK_NONINTERACTIVE threads.
>
> Ok, I think your patch is correct (we really do try to keep an order to
> those task flags), but the _real_ issue is that the comparisons are bogus.
>
> Using ">" for task states is wrong. It's a bitmask, and if you want to
> check multiple states, then we should just do so with
>
>         if (t->state & (TASK_xxx | TASK_yyy | ...))
>
> Oh, well. The inequality comparisons are shorter, and historical, so I

The inequality comparisons are faster or faster on some CPU.
We should use it if we can keep the order IMHO.

> guess it's debatable whether we should remove them all.
>
>                 Linus

--
Coywolf Qi Hunt
http://sosdg.org/~coywolf/
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