Re: [PATCH v2 2/7] proc/kcore: replace kclist_lock rwlock with rwsem

[Andrew Morton]

On Tue, 17 Jul 2018 20:24:05 -0700 Omar Sandoval <osandov@xxxxxxxxxxx> wrote:

> > > --- a/fs/proc/kcore.c
> > > +++ b/fs/proc/kcore.c
> > > @@ -59,8 +59,8 @@ struct memelfnote
> > >  };
> > >  
> > >  static LIST_HEAD(kclist_head);
> > > -static DEFINE_RWLOCK(kclist_lock);
> > > -static int kcore_need_update = 1;
> > > +static DECLARE_RWSEM(kclist_lock);
> > > +static atomic_t kcore_need_update = ATOMIC_INIT(1);
> > 
> > It's unclear why kcore_need_update was changed to atomic_t - it's still
> > updated under kclist_lock?
> 
> Not in the hotplug notifier (kcore_callback()) anymore, so I need the
> atomic_cmpxchg() in __kcore_update_ram().

Well that's just

	kcore_need_update = 1;

and turning that into an atomic_set doesn't change anything(?).

It's not a harmful change of course, but a bit ... odd.

> That could use a mention in the commit message.

That never hurts ;)