linux-kernel - Re: [PATCH 01/11] pci: add pci_bridge_release_unused_res and pci_bus_release_unused_bridge

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Date:	Tue, 19 Jan 2010 14:26:08 -0700
From:	Alex Chiang <achiang@...com>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Ingo Molnar <mingo@...e.hu>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ivan Kokshaysky <ink@...assic.park.msu.ru>,
	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>,
	Bjorn Helgaas <bjorn.helgaas@...com>,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH 01/11] pci: add pci_bridge_release_unused_res and
	pci_bus_release_unused_bridge_res

> +static void __ref pci_bus_release_bridge_resources(struct pci_bus *bus,
> +						   unsigned long type,
> +						   enum release_type rel_type)
> +{
> +	struct pci_dev *dev;
> +	bool is_leaf_bridge = true;
> +
> +	list_for_each_entry(dev, &bus->devices, bus_list) {
> +		struct pci_bus *b = dev->subordinate;
> +		if (!b)
> +			continue;
> +
> +		switch (dev->class >> 8) {
> +		case PCI_CLASS_BRIDGE_CARDBUS:
> +			is_leaf_bridge = false;
> +			break;
> +
> +		case PCI_CLASS_BRIDGE_PCI:
> +		default:
> +			is_leaf_bridge = false;
> +			if (rel_type == whole_subtree)
> +				pci_bus_release_bridge_resources(b, type,
> +							 whole_subtree);
> +			break;
> +		}
> +	}

I still don't understand this loop. Can't you write it like this:

	list_for_each_entry(dev, &bus->devices, bus_list) {
		struct pci_bus *b = dev->subordinate;
		if (!b)
			continue;

		is_leaf_bridge = false;

		if ((dev->class >> 8) == PCI_CLASS_BRIDGE_CARDBUS)
			continue;

		if (rel_type == whole_subtree)
			pci_bus_release_bridge_resources(b, type,
						whole_subtree);
	}

I'm looking at that 'default' label in your switch() statement
which causes us to always set is_leaf_bridge = false after 'b' is
valid.

/ac
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