Re: [PATCH] fix TASK_STOPPED vs TASK_NONINTERACTIVE interaction

[Paulo Marques <pmarques@grupopie.com>]

Linus Torvalds wrote:
> 
> On Thu, 29 Sep 2005, Oleg Nesterov wrote:
> 
>>[...]
>>However, TASK_NONINTERACTIVE > TASK_STOPPED, so this loop will not
>>count TASK_INTERRUPTIBLE | TASK_NONINTERACTIVE threads.
> 
> [...]
> 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 
> guess it's debatable whether we should remove them all.

I did a quick grep through 2.6.14-rc2 to see how many "them all" were, 
and the only two places I could find, where a inequality operator was 
being used on a task state, were this one in kernel/signal.c and another 
in kernel/exit.c:

./kernel/exit.c:1194:               unlikely(p->state > TASK_STOPPED)

So maybe it is not so bad to just change these to a bit mask and 
disallow inequality comparisons in the future, if you guys feel that is 
the way to go...

-- 
Paulo Marques - www.grupopie.com

The rule is perfect: in all matters of opinion our
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