Subject: Re: [PATCH V4 1/2] ACPI / EC: Fix broken 64bit big-endian users of 'global_lock'

From: Johannes Berg <[email-masked]>
Date: Fri, 25 Sep 2015 20:49:05 +0200

> Rafael wrote:
> > Actually, what about adding a local u32 variable, say val, here and 
> > doing
> > 
> > >  	if (!debugfs_create_x32("gpe", 0444, dev_dir, (u32 
> > > *)&first_ec->gpe))
> > >  		goto error;
> > >  	if (!debugfs_create_bool("use_global_lock", 0444, 
> > > dev_dir,
> > > -				 (u32 *)&first_ec->global_lock))
> > > +				 &first_ec->global_lock))
> > 
> > 	if (!debugfs_create_bool("use_global_lock", 0444, dev_dir, 
> > &val))
> > 
> > >  		goto error;
> > 
> > 	first_ec->global_lock = val;
> > 
> > And then you can turn val into bool just fine without changing the 
> > structure
> > definition.

Ok, then, but that means Rafael is completely wrong ...
debugfs_create_bool() takes a *pointer* and it needs to be long-lived,
it can't be on the stack. You also don't get a call when it changes.

If you cannot change the struct definition then you must implement a
debugfs file with its own read/write handlers.

johannes