linux-kernel - Re: [PATCH] can: flexcan: Fix an uninitialized variable issue

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Message-ID: <20210729113101.n5aucrwu56lyqhg7@pengutronix.de>
Date:   Thu, 29 Jul 2021 13:31:01 +0200
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc:     wg@...ndegger.com, davem@...emloft.net, kuba@...nel.org,
        angelo@...nel-space.org, linux-can@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] can: flexcan: Fix an uninitialized variable issue

On 29.07.2021 13:27:42, Christophe JAILLET wrote:
> If both 'clk_ipg' and 'clk_per' are NULL, we return an un-init value.
> So set 'err' to 0, to return success in such a case.

Thanks for the patch, a similar one has been posted before:
https://lore.kernel.org/linux-can/20210728075428.1493568-1-mkl@pengutronix.de/

> Fixes: d9cead75b1c6 ("can: flexcan: add mcf5441x support")
> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> ---
> Another way to fix it is to remove the NULL checks for 'clk_ipg' and
> 'clk_per' that been added in commit d9cead75b1c6.
> 
> They look useless to me because 'clk_prepare_enable()' returns 0 if it is
> passed a NULL pointer.

ACK, while the common clock framework's clk_prepare_enable() can handle
NULL pointers, the clock framework used on the mcf5441x doesn't.

> Having these explicit tests is maybe informational (i.e. these pointers
> can really be NULL) or have been added to silent a compiler or a static
> checker.
> 
> So, in case, I've left the tests and just fixed the un-init 'err' variable
> issue.

regards,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
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