Re: [PATCH] fbdev: Statically link the framebuffer notification functions

[Jon Smirl]

On 7/11/06, Antonino A. Daplas <adaplas@xxxxxxxxx> wrote:
> Jon Smirl wrote:
> > On 7/11/06, Antonino A. Daplas <adaplas@xxxxxxxxx> wrote:
> >> Jon Smirl wrote:
> >> > On 7/11/06, Antonino A. Daplas <adaplas@xxxxxxxxx> wrote:
> >> >> The backlight and lcd subsystems can be notified by the framebuffer
> >> layer
> >> >> of blanking events.  However, these subsystems, as a whole, can
> >> function
> >> >> independently from the framebuffer layer. But in order to enable to
> >> >> the lcd and backlight subsystems, the framebuffer has to be compiled
> >> >> also,
> >> >> effectively sucking in a huge amount of unneeded code. Besides, the
> >> >> dependency
> >> >> is introducing a lot of compilation problems.
> >> >
> >> > This code is effectively rebuilding a fb specific version of
> >> > inter_module_get/put., something that was removed earlier.
> >>
> >> Huh? I don't see any semblance of inter_module_* or symbol_* in there.
> >> Read the patch again.
> >
> > You are providing a fixed point to do a rendezvous between modules
> > without refcount tracking. That's what inter_module did.
>
> No, you're confused on inter_module. inter_module_* allows 2 or more
> modules to share data. The danger is that one module may disappear
> while the other is still accessing the data.
>
> In this case, there is absolutely no data sharing. One module can
> safely unload without affecting the other. The only danger is
> that one might be in a midst of a calling the callout function while
> the other is unregistering its notifier block. But then the notifier
> chain already protects this from happening.

The code looks ok but this sure smells like inter_module_*. I guess
inter_module had to deal with arbitrary users and this code is dealing
with a fixed set of clients which makes it more manageable.

Have you considered making this a generic service and not fb specific?

--
Jon Smirl
jonsmirl@xxxxxxxxx
-
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/