linux-kernel - Re: [PATCH] pwm: core: Zero-initialize the temp state

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Message-ID: <20230226091752.wtnj7oqzmn6azahl@pengutronix.de>
Date:   Sun, 26 Feb 2023 10:17:52 +0100
From:   Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
To:     Munehisa Kamata <kamatam@...zon.com>
Cc:     thierry.reding@...il.com, tobetter@...il.com,
        linux-pwm@...r.kernel.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH] pwm: core: Zero-initialize the temp state

Hello,

On Sat, Feb 25, 2023 at 05:37:21PM -0800, Munehisa Kamata wrote:
> Zero-initialize the on-stack structure to avoid unexpected behaviors. Some
> drivers may not set or initialize all the values in pwm_state through their
> .get_state() callback and therefore some random values may remain there and
> be set into pwm->state eventually.
> 
> This actually caused regression on ODROID-N2+ as reported in [1]; kernel
> fails to boot due to random panic or hang-up.
> 
> [1] https://forum.odroid.com/viewtopic.php?f=177&t=46360

Looking through the report I wonder what actually made the machine fail
to boot. Doesn't this paper over a problem that should be fixed (also)
somewhere else?

Which driver is the one that the problem occur for?

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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