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From: Nathan Chancellor <natechancellor@gmail.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Len Brown <lenb@kernel.org>,
	Mika Westerberg <mika.westerberg@linux.intel.com>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Hans de Goede <hdegoede@redhat.com>,
	Sakari Ailus <sakari.ailus@linux.intel.com>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Keith Busch <keith.busch@intel.com>,
	Heikki Krogerus <heikki.krogerus@linux.intel.com>,
	linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org,
	clang-built-linux@googlegroups.com
Subject: Re: [PATCH] acpi: fix false-positive -Wuninitialized warning
Date: Fri, 12 Jul 2019 11:00:24 -0700
Message-ID: <20190712180024.GA21382@archlinux-threadripper> (raw)
In-Reply-To: <20190712090148.36582-1-arnd@arndb.de>

On Fri, Jul 12, 2019 at 11:01:21AM +0200, Arnd Bergmann wrote:
> clang gets confused by an uninitialized variable in what looks
> to it like a never executed code path:
> 
> arch/x86/kernel/acpi/boot.c:618:13: error: variable 'polarity' is uninitialized when used here [-Werror,-Wuninitialized]
>         polarity = polarity ? ACPI_ACTIVE_LOW : ACPI_ACTIVE_HIGH;
>                    ^~~~~~~~
> arch/x86/kernel/acpi/boot.c:606:32: note: initialize the variable 'polarity' to silence this warning
>         int rc, irq, trigger, polarity;
>                                       ^
>                                        = 0
> arch/x86/kernel/acpi/boot.c:617:12: error: variable 'trigger' is uninitialized when used here [-Werror,-Wuninitialized]
>         trigger = trigger ? ACPI_LEVEL_SENSITIVE : ACPI_EDGE_SENSITIVE;
>                   ^~~~~~~
> arch/x86/kernel/acpi/boot.c:606:22: note: initialize the variable 'trigger' to silence this warning
>         int rc, irq, trigger, polarity;
>                             ^
>                              = 0
> 
> This is unfortunately a design decision in clang and won't be fixed.
> 
> Changing the acpi_get_override_irq() macro to an inline function
> reliably avoids the issue.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>

      parent reply index

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-12  9:01 Arnd Bergmann
2019-07-12 11:47 ` Andy Shevchenko
2019-07-12 18:00 ` Nathan Chancellor [this message]

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