Re: Where did find_bus() go in 2.6.18?

From: Adrian Bunk
Date: Mon Nov 20 2006 - 12:36:16 EST


On Mon, Nov 20, 2006 at 04:13:22PM +0200, Paul Sokolovsky wrote:
>...
> But note that I don't really ask mainline kernel developers how to
> fix this driver - I would actually be ashamed to do so, as I myself a
> (newbie) kernel hacker. So, the question stays the same, though I
> probably reformulate it a bit stronger now: how it came that ability
> to query buses (at all) was removed from 2.6.18?
>
> As it was before, it was clear that LDM consists of multiple layers,
> and each layer offers consistent and complete set of operations on it,
> like adding new object on this layer, removing, adding child, removing
> child, *and* query objects on this level or among childs. I may miss
> some accidental gaps in that picture of course, but it still was an
> integral, complete design paradigm offering full dynamicity and
> introspection.
>
> And suddenly - oops, in 2.6.18 we lose ability to query the highest
> level of hierarchy, namely bus set. And on what criterion? "unused". I
> would really dream that such core, the most basic APIs are not being
> defined in terms of "someone does use it right now". A method to query
> objects of core kernel data sets is just integral part of interface to
> these datasets, you cannot remove it and not cripple such interface.
> Again, it's loss of introspection, and that's not just "cleanup", it's
> a paradigm shift.
>...

As Documentation/stable_api_nonsense.txt explains, there is no stable
kernel API. If you don't want to get the APIs your driver uses
changed/removed you should really try to get it merged into mainline.

The find_bus() case is even more interesting since you are using it in a
driver although it has never been exported to modules. Considering that
you anyway have to patch the kernel for getting your driver running
(since it won't run as a module against an unmodified kernel), you could
simply undo my patch locally until you submit your driver for inclusion
in mainline.

> Paul

cu
Adrian

--

"Is there not promise of rain?" Ling Tan asked suddenly out
of the darkness. There had been need of rain for many days.
"Only a promise," Lao Er said.
Pearl S. Buck - Dragon Seed

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