linux-kernel - Re: [PATCH 2/4] PCI: pciehp: bail out if pci_hp_add

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Date: Sat, 4 May 2024 10:54:15 +0200
From: Lukas Wunner <lukas@...ner.de>
To: Nam Cao <namcao@...utronix.de>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>, Yinghai Lu <yinghai@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Rajesh Shah <rajesh.shah@...el.com>, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH 2/4] PCI: pciehp: bail out if pci_hp_add_bridge() fails

On Fri, May 03, 2024 at 09:23:20PM +0200, Nam Cao wrote:
> If there is no bus number available for the downstream bus of the
> hot-plugged bridge, pci_hp_add_bridge() will fail. The driver proceeds
> regardless, and the kernel crashes.
> 
> Abort if pci_hp_add_bridge() fails.
[...]
> --- a/drivers/pci/hotplug/pciehp_pci.c
> +++ b/drivers/pci/hotplug/pciehp_pci.c
> @@ -58,8 +58,13 @@ int pciehp_configure_device(struct controller *ctrl)
>  		goto out;
>  	}
>  
> -	for_each_pci_bridge(dev, parent)
> -		pci_hp_add_bridge(dev);
> +	for_each_pci_bridge(dev, parent) {
> +		if (pci_hp_add_bridge(dev)) {
> +			pci_stop_and_remove_bus_device(dev);
> +			ret = -EINVAL;
> +			goto out;
> +		}
> +	}

Is the pci_stop_and_remove_bus_device() really necessary here?
Why not just leave the bridge as is, without any child devices?

Thanks,

Lukas