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Date: Tue, 18 Oct 2016 15:05:59 +0200 (CEST)
From: Jiri Kosina <jikos@kernel.org>
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To: Arnd Bergmann <arnd@arndb.de>
cc: Linus Torvalds <torvalds@linux-foundation.org>,
        linux-kernel@vger.kernel.org, x86@kernel.org,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        "Luis R. Rodriguez" <mcgrof@kernel.org>
Subject: Re: [PATCH 22/28] x86: apm: avoid uninitialized data
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References: <20161017220342.1627073-1-arnd@arndb.de> <20161017221650.1902729-3-arnd@arndb.de>
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On Tue, 18 Oct 2016, Arnd Bergmann wrote:

> apm_bios_call() can fail, and return a status in its argument
> structure. If that status however is zero during a call from
> apm_get_power_status(), we end up using data that may have
> never been set, as reported by "gcc -Wmaybe-uninitialized":
> 
> arch/x86/kernel/apm_32.c: In function ‘apm’:
> arch/x86/kernel/apm_32.c:1729:17: error: ‘bx’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> arch/x86/kernel/apm_32.c:1835:5: error: ‘cx’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> arch/x86/kernel/apm_32.c:1730:17: note: ‘cx’ was declared here
> arch/x86/kernel/apm_32.c:1842:27: error: ‘dx’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> arch/x86/kernel/apm_32.c:1731:17: note: ‘dx’ was declared here
> 
> This changes the function to return "APM_NO_ERROR" here, which
> makes the code more robust to broken BIOS versions, and avoids
> the warning.
> 
> Cc: x86@kernel.org
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Makes sense.

Reviewed-by: Jiri Kosina <jkosina@suse.cz>

Thanks,

-- 
Jiri Kosina
SUSE Labs