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Date: Tue, 19 Jan 2010 14:11:10 -0800
From: Yinghai Lu <yinghai@kernel.org>
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To: Alex Chiang <achiang@hp.com>
CC: Jesse Barnes <jbarnes@virtuousgeek.org>, Ingo Molnar <mingo@elte.hu>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
       Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>,
       Bjorn Helgaas <bjorn.helgaas@hp.com>, linux-kernel@vger.kernel.org,
       linux-pci@vger.kernel.org
Subject: Re: [PATCH 01/11] pci: add pci_bridge_release_unused_res and	pci_bus_release_unused_bridge_res
References: <1263640037-24134-1-git-send-email-yinghai@kernel.org> <1263640037-24134-2-git-send-email-yinghai@kernel.org> <20100119212608.GF11010@ldl.fc.hp.com>
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On 01/19/2010 01:26 PM, Alex Chiang wrote:
>> +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.

ok