linux-kernel - Re: [PATCH 1/1] acpi: unbreak ACPI_HANDLE(), encapsulate fwnode

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Message-ID: <1712250.n7upXYL8Lq@aspire.rjw.lan>
Date:   Tue, 19 Sep 2017 22:39:36 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Mika Westerberg <mika.westerberg@...ux.intel.com>,
        john.hubbard@...il.com, Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc:     LKML <linux-kernel@...r.kernel.org>, Rob Herring <robh@...nel.org>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        John Hubbard <jhubbard@...dia.com>
Subject: Re: [PATCH 1/1] acpi: unbreak ACPI_HANDLE(), encapsulate fwnode_operations

On Tuesday, September 19, 2017 9:44:00 AM CEST Mika Westerberg wrote:
> On Fri, Sep 15, 2017 at 05:35:27PM -0700, john.hubbard@...il.com wrote:
> > From: John Hubbard <jhubbard@...dia.com>
> > 
> > Due to commit db3e50f3234b ("device property: Get rid of struct
> > fwnode_handle type field"), ACPI_HANDLE() inadvertently became
> > a GPL-only call. The call path that led to that was:
> > 
> > ACPI_HANDLE()
> >     ACPI_COMPANION()
> >         to_acpi_device_node()
> >             is_acpi_device_node()
> >                 acpi_device_fwnode_ops
> >                     DECLARE_ACPI_FWNODE_OPS(acpi_device_fwnode_ops);
> > 
> > ...and the new DECLARE_ACPI_FWNODE_OPS() includes
> > EXPORT_SYMBOL_GPL, whereas previously it was a static struct.
> > 
> > In order to avoid changing any of that, let's instead provide ever
> > so slightly better encapsulation of those struct fwnode_operations
> > instances. Those do not really need to be directly used in
> > inline function calls in header files. Simply moving two small
> > functions (is_acpi_device_node and is_acpi_data_node) out of
> > acpi_bus.h, and into a .c file, does that.
> > 
> > That leaves the internals of struct fwnode_operations as GPL-only
> > (which I think was the intent all along), but un-breaks any driver
> > code out there that relies on the ACPI subsystem's being (historically)
> > an EXPORT_SYMBOL-usable system. By that, I mean, ACPI_HANDLE() and
> > other basic ACPI calls were non-GPL-protected.
> > 
> > Also, while I'm there, remove a tiny bit of redundancy that was missed
> > in the earlier commit, by having is_acpi_node() use the other two
> > routines, instead of checking fwnode directly.
> > 
> > Signed-off-by: John Hubbard <jhubbard@...dia.com>
> 
> Acked-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
> 

OK, applied.

Side note: I'm slightly unhappy with the number of checks in the
ACPI_COMPANION() path.

Do we really ever pass anything other than struct acpi_device to
ACPI_COMPANION_SET() as the second arg?

Thanks,
Rafael