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SubjectRe: [RFC] mm/shrinker: define INIT_SHRINKER macro
On Sat, 11 Jul 2015 10:25:13 +0900 Sergey Senozhatsky <sergey.senozhatsky@gmail.com> wrote:

> > > I was thinking of a trivial INIT_SHRINKER macro to init `struct shrinker'
> > > internal members (composed in email client, not tested)
> > >
> > > include/linux/shrinker.h
> > >
> > > #define INIT_SHRINKER(s) \
> > > do { \
> > > (s)->nr_deferred = NULL; \
> > > INIT_LIST_HEAD(&(s)->list); \
> > > } while (0)
> >
> > Spose so. Although it would be simpler to change unregister_shrinker()
> > to bale out if list.next==NULL and then say "all zeroes is the
> > initialized state".
>
> Yes, or '->nr_deferred == NULL' -- we can't have NULL ->nr_deferred
> in a properly registered shrinker (as of now)

list.next seems safer because that will always be non-zero. But
whatever - we can change it later.

> But that will not work if someone has accidentally passed not zeroed
> out pointer to unregister.

I wouldn't worry about that really. If you pass a pointer to
uninitialized memory, the kernel will explode. That's true of just
about every pointer-accepting function in the kernel.




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