From mboxrd@z Thu Jan  1 00:00:00 1970
From: johannes@sipsolutions.net (Johannes Berg)
Date: Fri, 25 Sep 2015 20:49:05 +0200
Subject: [PATCH V4 1/2] ACPI / EC: Fix broken 64bit big-endian users of
 'global_lock'
In-Reply-To: <20150925184741.GF5951@linux>
 (sfid-20150925_204744_507179_F4A02CF2)
References: <e28c4b4deaf766910c366ab87b64325da59c8ad6.1443198783.git.viresh.kumar@linaro.org>
 <1443202945.2161.8.camel@sipsolutions.net> <20150925184741.GF5951@linux>
 (sfid-20150925_204744_507179_F4A02CF2)
Message-ID: <1443206945.2161.9.camel@sipsolutions.net>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org


> 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