linux-kernel - Re: [PATCH 15/23] interconnect: exynos: fix registration race

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Date:   Thu, 2 Feb 2023 13:17:30 +0100
From:   Johan Hovold <johan@...nel.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     Johan Hovold <johan+linaro@...nel.org>,
        Georgi Djakov <djakov@...nel.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Sylwester Nawrocki <s.nawrocki@...sung.com>,
        Artur Świgoń <a.swigon@...sung.com>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        linux-pm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-arm-msm@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH 15/23] interconnect: exynos: fix registration race

On Thu, Feb 02, 2023 at 12:04:49PM +0100, Krzysztof Kozlowski wrote:
> On 01/02/2023 11:15, Johan Hovold wrote:

> > @@ -98,12 +98,13 @@ static int exynos_generic_icc_remove(struct platform_device *pdev)
> >  	struct exynos_icc_priv *priv = platform_get_drvdata(pdev);
> >  	struct icc_node *parent_node, *node = priv->node;
> >  
> > +	icc_provider_deregister(&priv->provider);
> > +
> >  	parent_node = exynos_icc_get_parent(priv->dev->parent->of_node);
> >  	if (parent_node && !IS_ERR(parent_node))
> >  		icc_link_destroy(node, parent_node);
> >  
> >  	icc_nodes_remove(&priv->provider);
> > -	icc_provider_del(&priv->provider);
> >  
> >  	return 0;
> >  }
> > @@ -132,15 +133,11 @@ static int exynos_generic_icc_probe(struct platform_device *pdev)
> >  	provider->inter_set = true;
> >  	provider->data = priv;
> >  
> > -	ret = icc_provider_add(provider);
> > -	if (ret < 0)
> > -		return ret;
> > +	icc_provider_init(provider);
> >  
> >  	icc_node = icc_node_create(pdev->id);
> > -	if (IS_ERR(icc_node)) {
> > -		ret = PTR_ERR(icc_node);
> > -		goto err_prov_del;
> > -	}
> > +	if (IS_ERR(icc_node))
> > +		return PTR_ERR(icc_node);
> >  
> >  	priv->node = icc_node;
> >  	icc_node->name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%pOFn",
> > @@ -171,14 +168,17 @@ static int exynos_generic_icc_probe(struct platform_device *pdev)
> >  			goto err_pmqos_del;
> >  	}
> >  
> > +	ret = icc_provider_register(provider);
> > +	if (ret < 0)
> > +		goto err_pmqos_del;
> 
> If I understand correctly there is no need for icc_link_destroy() in
> error path here, right? Even in case of probe retry (defer or whatever
> reason) - the link will be removed with icc_nodes_remove()?

Correct, it is no longer needed after the first patch in this series.

The exynos driver was the only driver that bothered to remove links
explicitly, all the others expected the interconnect framework to do so
when destroying nodes even if that was not case until now.

Johan