From: Arnd Bergmann <arnd@arndb.de>
To: linux-arm-kernel@lists.infradead.org
Cc: Roman Volkov <v1ron@mail.ru>,
Michael Turquette <mturquette@baylibre.com>,
Stephen Boyd <sboyd@codeaurora.org>,
linux-kernel@vger.kernel.org, Tony Prisk <linux@prisktech.co.nz>,
Andrzej Hajda <a.hajda@samsung.com>,
linux-clk@vger.kernel.org
Subject: Re: [PATCH] clk: vt8500: don't return possibly uninitialized data
Date: Wed, 03 Feb 2016 10:15:34 +0100 [thread overview]
Message-ID: <1624352.DBIo65mLZO@wuerfel> (raw)
In-Reply-To: <20160203113626.4a3f4f8a@v1ron-s7>
On Wednesday 03 February 2016 11:36:26 Roman Volkov wrote:
>
> Hi Arnd,
>
> Thanks for fixing this code! Did someone reproduce this bug, or this
> is something theoretical, based on the code analysis? I just never
> heard about the issue. I can look into the code on the weekends too, I
> have WM8505\WM8650 machines to test.
I only fixed it after analysing the gcc warnings I got after Andrzej Hajda's
patch, and he also did it to fix the initial problem he found using
coccinelle, so I don't think anyone has run into the problem on live
hardware.
As long as all drivers ask for clock rates that are valid, you won't
see either problem.
> Is it enough to run the regular kernel build for WM8650 to see the
> warnings, or there are special options in the kernel to run the compiler
> test?
The warning is hidden if you build with -Os (CONFIG_CC_OPTIMIZE_FOR_SIZE),
and it may not happen with all gcc versions. I was using gcc-5.2.
Arnd
WARNING: multiple messages have this Message-ID (diff)
From: arnd@arndb.de (Arnd Bergmann)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] clk: vt8500: don't return possibly uninitialized data
Date: Wed, 03 Feb 2016 10:15:34 +0100 [thread overview]
Message-ID: <1624352.DBIo65mLZO@wuerfel> (raw)
In-Reply-To: <20160203113626.4a3f4f8a@v1ron-s7>
On Wednesday 03 February 2016 11:36:26 Roman Volkov wrote:
>
> Hi Arnd,
>
> Thanks for fixing this code! Did someone reproduce this bug, or this
> is something theoretical, based on the code analysis? I just never
> heard about the issue. I can look into the code on the weekends too, I
> have WM8505\WM8650 machines to test.
I only fixed it after analysing the gcc warnings I got after Andrzej Hajda's
patch, and he also did it to fix the initial problem he found using
coccinelle, so I don't think anyone has run into the problem on live
hardware.
As long as all drivers ask for clock rates that are valid, you won't
see either problem.
> Is it enough to run the regular kernel build for WM8650 to see the
> warnings, or there are special options in the kernel to run the compiler
> test?
The warning is hidden if you build with -Os (CONFIG_CC_OPTIMIZE_FOR_SIZE),
and it may not happen with all gcc versions. I was using gcc-5.2.
Arnd
next prev parent reply other threads:[~2016-02-03 9:15 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-01 10:19 [PATCH] clk: vt8500: don't return possibly uninitialized data Arnd Bergmann
2016-02-01 10:19 ` Arnd Bergmann
2016-02-02 1:15 ` Stephen Boyd
2016-02-02 1:15 ` Stephen Boyd
2016-02-02 12:49 ` Arnd Bergmann
2016-02-02 12:49 ` Arnd Bergmann
2016-02-02 12:49 ` Arnd Bergmann
2016-02-02 19:47 ` Stephen Boyd
2016-02-02 19:47 ` Stephen Boyd
2016-02-02 20:00 ` Arnd Bergmann
2016-02-02 20:00 ` Arnd Bergmann
2016-02-03 8:36 ` Roman Volkov
2016-02-03 8:36 ` Roman Volkov
2016-02-03 8:36 ` Roman Volkov
2016-02-03 9:15 ` Arnd Bergmann [this message]
2016-02-03 9:15 ` Arnd Bergmann
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