linux-kernel - Re: [PATCH] PCI: dwc: keystone: Free IRQ in `ks_pcie_remove` and the error handling section of `ks_pcie

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Date:   Tue, 16 May 2023 14:49:36 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Xiangyi Zeng <xyzeng@....xidian.edu.cn>
Cc:     Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Rob Herring <robh@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Kishon Vijay Abraham I <kishon@...com>,
        hust-os-kernel-patches@...glegroups.com,
        Dongliang Mu <dzm91@...t.edu.cn>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI: dwc: keystone: Free IRQ in `ks_pcie_remove` and the
 error handling section of `ks_pcie_probe`

On Tue, May 16, 2023 at 01:16:59PM +0800, Xiangyi Zeng wrote:
> Smatch complains that:
> drivers/pci/controller/dwc/pci-keystone.c:1303 ks_pcie_probe() warn:
> 'irq' from request_irq() not released on lines: 1183,1187,1303.

Make this the entire warning line from smatch with no extra newlines
inserted.

> "ks-pcie-error-irq" was requested in the `ks_pcie_probe` function, but
> was not freed neither in the error handling part of `ks_pcie_probe`
> nor in the `ks_pcie_remove` function.
> 
> Fix this by adding `free_irq` in `ks_pcie_remove` and in a new error
> handling label `err_alloc` after `err_link` in `ks_pcie_probe`. In
> `ks_pcie_probe`, if `phy` or `link` memory allocation fails, we will
> fall to `err_alloc`. If any other error occurs that leads to
> `err_get_sync` or `err_link`, we end up going to `err_alloc`.

I think the backticks (`) are markdown that makes these "code".
Personally I think ks_pcie_probe() is more readable than
`ks_pcie_probe` since most people (I think) read these in plain-ASCII
situations.  And using backticks for labels and local variables seems
like overkill.

> Fixes: 0790eb175ee0 ("PCI: keystone: Cleanup error_irq configuration")
> Signed-off-by: Xiangyi Zeng <xyzeng@....xidian.edu.cn>
> Reviewed-by: Dongliang Mu <dzm91@...t.edu.cn>

It's best if the Reviewed-by tag is not added until Dongliang sends
email with that tag directly to the mailing list.  Internal reviews
before posting to the mailing list aren't worth much.

> @@ -1309,12 +1316,14 @@ static int __exit ks_pcie_remove(struct platform_device *pdev)
>  	struct device_link **link = ks_pcie->link;
>  	int num_lanes = ks_pcie->num_lanes;
>  	struct device *dev = &pdev->dev;
> +	int irq = platform_get_irq(pdev, 0);

I think it's better to save the irq we looked up in ks_pcie_probe()
and free *that*.  It's probably the same thing you get by calling
platform_get_irq() again, but it seems cleaner to me to save what we
got in ks_pcie_probe().

>  	pm_runtime_put(dev);
>  	pm_runtime_disable(dev);
>  	ks_pcie_disable_phy(ks_pcie);
>  	while (num_lanes--)
>  		device_link_del(link[num_lanes]);
> +	free_irq(irq, ks_pcie);
>  
>  	return 0;
>  }
> -- 
> 2.34.1
>