On Tue, 2007-03-27 at 22:58 -0700, Greg KH wrote:
> On Wed, Mar 28, 2007 at 01:39:26PM +0800, Shaohua Li wrote:
> > On Tue, 2007-03-27 at 22:27 -0700, Greg KH wrote:
> > >
> > > Putting more than one kobject in the same structure is a broken design.
> > > How can you control the lifetime rules properly if there are two
> > > reference counts for the same structure? It doesn't work.
> > >
> > > If you really need something like this, then just use a pointer to a
> > > kobject for one of them instead of embedding it. Why do you need two
> > > different kobjects here?
> > Our data structure is something like below:
> >
> > struct foo {
> > kobject kobja;
> > }
> >
> > struct bar {
> > struct foo foo[];
>
> Ick, don't do that...
why?
> > kobject kobjb
> > }
> >
> > kobjb's .release will free struct bar. kobjb is the parent of kobja. if
> > you have a reference on kobja, then kobjb can't be released too, right?
> > So we only kobjb provide a .release to free the memory, kobja's .release
> > isn't required.
>
> Why not just use the "normal" parent/child relationship with the
> kobjects like the rest of the kernel does?
I still didn't get the reason why we couldn't do this in the way of my
patch. As I said, there isn't risk to use 'freed memory'. I can make the
'struct foo' a pointer, but this will mess the cpuidle driver.
Thanks,
Shaohua
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