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

[Omar Sandoval]

On Tue, Jul 17, 2018 at 07:38:41PM -0700, Andrew Morton wrote:
> On Thu, 12 Jul 2018 17:09:34 -0700 Omar Sandoval <osandov@xxxxxxxxxxx> wrote:
> 
> > From: Omar Sandoval <osandov@xxxxxx>
> > 
> > Now we only need kclist_lock from user context and at fs init time, and
> > the following changes need to sleep while holding the kclist_lock.
> > 
> > ...
> >
> > --- 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(). That could use a mention in
the commit message.

> Maybe it's for a later patch.
> 
>