Re: One comment on the __release_region in kernel/resource.c

[Geert Uytterhoeven]

On Mon, Oct 3, 2011 at 15:35, Wei Yang <weiyang.kernel@xxxxxxxxx> wrote:
> 2011/10/3 Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
>> On Mon, Oct 3, 2011 at 12:24, KAMEZAWA Hiroyuki
>> <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
>> > On Sun, 2 Oct 2011 21:57:07 +0800
>> > Wei Yang <weiyang.kernel@xxxxxxxxx> wrote:
>> >
>> >> Dear experts,
>> >>
>> >> I am viewing the source code of __release_region() in
>> >> kernel/resource.c.
>> >> And I have one comment for the performance issue.
>> >>
>> >> For example, we have a resource tree like this.
>> >> 10-89
>> >> Â Â20-79
>> >> Â Â Â Â30-49
>> >> Â Â Â Â55-59
>> >> Â Â Â Â60-64
>> >> Â Â Â Â65-69
>> >> Â Â80-89
>> >> 100-279
>> >>
>> >> If the caller wants to release a region of [50,59], the original code
>> >> will
>> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â^^^^^^^
>> Do you really mean [50,59]?
>
> Yes.
>>
>> I don't think that's allowed, as the tree has [55,59], so you would
>> release a
>> larger region that allocated.
>
> So you mean the case I mentioned will not happen?

Indeed, it should not happen.
Actually I'm surprised it doesn't return an error code.

> Actually, I believe every developer should pass the resource region which
> has been allocated.
> While if some one made a mistake and pass a region which is not allocated
> before and overlap
> some "BUSY" region?

Gr{oetje,eeting}s,

            Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
             Â Â -- Linus Torvalds
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/