linux-kernel - Re: clk: rockchip: Checking a kmemdup() call in rockchip_clk_register

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Date:   Sun, 13 Oct 2019 10:45:09 +0200
From:   Markus Elfring <Markus.Elfring@....de>
To:     Heiko Stübner <heiko@...ech.de>,
        linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, kernel-janitors@...r.kernel.org
Cc:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Aditya Pakki <pakki001@....edu>, Kangjie Lu <kjlu@....edu>,
        Navid Emamdoost <emamd001@....edu>,
        Stephen McCamant <smccaman@....edu>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: clk: rockchip: Checking a kmemdup() call in
 rockchip_clk_register_pll()

>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/clk/rockchip/clk-pll.c?id=1c0cc5f1ae5ee5a6913704c0d75a6e99604ee30a#n913
>> https://elixir.bootlin.com/linux/v5.4-rc2/source/drivers/clk/rockchip/clk-pll.c#L913
>>
>> * Do you find the usage of the format string “%s: could not allocate
>>   rate table for %s\n” still appropriate at this place?
>
> If there is an internal "no-memory" output from inside kmemdup now,
> I guess the one in the clock driver would be a duplicate and could go away.

How do you think about to recheck information sources around
the Linux allocation failure report?
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/coding-style.rst?id=da94001239cceb93c132a31928d6ddc4214862d5#n878


>> * Is there a need to adjust the error handling here?
>
> There is no need for additional error handling.

If you would like to omit the macro call “WARN”, I would expect also
to express a corresponding null pointer check.


> Like if the rate-table could not be duplicated,
> the clock will still report the correct clockrate
> you can just not set a new rate.

How much will a different system configuration matter finally?
(Do you really want to treat this setting as “optional”?)


> And for a system it's always better to have the clock driver present
> than for all device-drivers to fail probing. Especially as this start as
> core clock driver, so there is no deferring possible.

I imagine that such a view can be clarified further.

Regards,
Markus