linux-kernel - Re: [PATCH 2/2] [v3] acpi: allow building without CONFIG_HAS

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Message-ID: <ZyJNTQSv3bNbgPf_@smile.fi.intel.com>
Date: Wed, 30 Oct 2024 17:14:21 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Arnd Bergmann <arnd@...nel.org>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>, Arnd Bergmann <arnd@...db.de>,
	Len Brown <lenb@...nel.org>,
	Jarred White <jarredwhite@...ux.microsoft.com>,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] [v3] acpi: allow building without CONFIG_HAS_IOPORT

On Wed, Oct 30, 2024 at 05:13:15PM +0200, Andy Shevchenko wrote:
> On Wed, Oct 30, 2024 at 12:36:41PM +0000, Arnd Bergmann wrote:
> > From: Arnd Bergmann <arnd@...db.de>
> > 
> > CONFIG_HAS_IOPORT will soon become optional and cause a build time
> > failure when it is disabled but a driver calls inb()/outb(). At the
> > moment, all architectures that can support ACPI have port I/O, but this
> > is not necessarily the case in the future on non-x86 architectures.
> > The result is a set of errors like:
> > 
> > drivers/acpi/osl.c: In function 'acpi_os_read_port':
> > include/asm-generic/io.h:542:14: error: call to '_inb' declared with attribute error: inb()) requires CONFIG_HAS_IOPORT
> > 
> > Nothing should actually call these functions in this configuration,
> > and if it does, the result would be undefined behavior today, possibly
> > a NULL pointer dereference.
> > 
> > Change the low-level functions to return a proper error code when
> > HAS_IOPORT is disabled.
> 
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>

...

> > +	if (!IS_ENABLED(CONFIG_HAS_IOPORT)) {
> > +		/*
> > +		 * set all-1 result as if reading from non-existing
> > +		 * I/O port
> > +		 */
> 
> Don't know if Rafael can / want to tweak this, but would be nice to follow
> standard style for multi-line comments.
> 
> 		/*
> 		 * Set all-1 result as if reading from non-existing
> 		 * I/O port.
> 		 */
> 
> > +		*value = GENMASK(width, 0);

Actually, shouldn't this be width - 1 ?

> > +		return AE_NOT_IMPLEMENTED;
> > +	}

-- 
With Best Regards,
Andy Shevchenko