Re: [PATCH v2] jump_label: reduce the size of struct static_key

[Jason Baron]

On 01/21/2017 02:07 AM, Ingo Molnar wrote:
> * Jason Baron <jbaron@xxxxxxxxxx> wrote:
>
> > > For example the last line could sure be written as:
> > >
> > > 			key->entries = jlm->entries;
> > > 			key->type |= static_key_type(key);
> > >
> > > right?
> >
> > Hi,
> >
> > So that is going to over-write the static_key_type(key) in the first
> > assignment. If the order is reversed we can't just |= in the pointer type.
>
> Indeed, I missed that.
>
> > How about:
> >
> > static void jump_key_set_entries(struct static_key *key, struct jump_entry *entries)
> > {
> >        unsigned long type;
> >
> >        type = static_key_type(key);
> >        key->entries = entries;
> >        key->type |= type;
> > }
> >
> > and then we can also add:
> >
> > void jump_key_set_mod(struct static_key *key, struct static_key_mod *mod)
> >
> > doing basically the same thing. That will avoid the casts that you called
> > out.
> >
> > better?
>
> Yeah - and it should generate the exact same code, right?

yes, looks identical.

> I'd also add a short comment to the helper function that points out the
> union/aliasing, in case anyone is wondering.

Ok, I'll add that to v3.

Thanks,

-Jason