linux-kernel - Re: [PATCH v3 4/9] drivers: thermal: tsens: Release device in success path

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Date:   Thu, 2 Jan 2020 11:29:25 -0800
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Amit Kucheria <amit.kucheria@...aro.org>
Cc:     linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        swboyd@...omium.org, sivaa@...eaurora.org,
        Andy Gross <agross@...nel.org>,
        Amit Kucheria <amit.kucheria@...durent.com>,
        linux-pm@...r.kernel.org
Subject: Re: [PATCH v3 4/9] drivers: thermal: tsens: Release device in
 success path

On Thu 02 Jan 06:54 PST 2020, Amit Kucheria wrote:

> We don't currently call put_device in case of successfully initialising
> the device.
> 
> Allow control to fall through so we can use same code for success and
> error paths to put_device.
> 

Given the relationship between priv->dev and op I think this wouldn't be
a problem in practice, but there's two devm_ioremap_resource() done on
op->dev in this function. So you're depending on op->dev to stick
around, but with this patch you're no longer expressing that dependency.

That said, it looks iffy to do devm_ioremap_resource() on op->dev and
then create a regmap on priv->dev using that resource. So I think it
would be better to do platform_get_source() on op, and then
devm_ioremap_resource() on priv->dev, in which case the regmap backing
memory will be related to the same struct device as the regmap and it
makes perfect sense to put_device() the op->dev when you're done
inspecting it's resources.

Regards,
Bjorn

> Signed-off-by: Amit Kucheria <amit.kucheria@...aro.org>
> ---
>  drivers/thermal/qcom/tsens-common.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/thermal/qcom/tsens-common.c b/drivers/thermal/qcom/tsens-common.c
> index 1cbc5a6e5b4f..e84e94a6f1a7 100644
> --- a/drivers/thermal/qcom/tsens-common.c
> +++ b/drivers/thermal/qcom/tsens-common.c
> @@ -687,8 +687,6 @@ int __init init_common(struct tsens_priv *priv)
>  	tsens_enable_irq(priv);
>  	tsens_debug_init(op);
>  
> -	return 0;
> -
>  err_put_device:
>  	put_device(&op->dev);
>  	return ret;
> -- 
> 2.20.1
>