linux-kernel - Re: [PATCH 3/4] clk: qcom: clk-krait: add hw_parent check for div2_round

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Message-ID: <b7de49e0-c0cf-5062-8426-dcb54272d350@linaro.org>
Date:   Fri, 29 Apr 2022 17:53:32 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Ansuel Smith <ansuelsmth@...il.com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Sricharan R <sricharan@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] clk: qcom: clk-krait: add hw_parent check for
 div2_round_rate

On 29/04/2022 15:01, Ansuel Smith wrote:
> Check if hw_parent is present before calculating the round_rate to
> prevent kernel panic. On error -EINVAL is reported.
> 
> Signed-off-by: Ansuel Smith <ansuelsmth@...il.com>

I see that other clock drivers do not perform this check. Which path 
leads to this oops?

> ---
>   drivers/clk/qcom/clk-krait.c | 7 ++++++-
>   1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/clk/qcom/clk-krait.c b/drivers/clk/qcom/clk-krait.c
> index 90046428693c..6c367ad6506a 100644
> --- a/drivers/clk/qcom/clk-krait.c
> +++ b/drivers/clk/qcom/clk-krait.c
> @@ -84,7 +84,12 @@ EXPORT_SYMBOL_GPL(krait_mux_clk_ops);
>   static long krait_div2_round_rate(struct clk_hw *hw, unsigned long rate,
>   				  unsigned long *parent_rate)
>   {
> -	*parent_rate = clk_hw_round_rate(clk_hw_get_parent(hw), rate * 2);
> +	struct clk_hw *hw_parent = clk_hw_get_parent(hw);
> +
> +	if (!hw_parent)
> +		return -EINVAL;
> +
> +	*parent_rate = clk_hw_round_rate(hw_parent, rate * 2);
>   	return DIV_ROUND_UP(*parent_rate, 2);
>   }
>   


-- 
With best wishes
Dmitry