linux-kernel - Re: [PATCH v2 02/13] PCI: prevent duplicate slot names

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Date:	Thu, 11 Sep 2008 04:37:46 -0600
From:	Alex Chiang <achiang@...com>
To:	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>
Cc:	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	jbarnes@...tuousgeek.org, kristen.c.accardi@...el.com,
	matthew@....cx
Subject: Re: [PATCH v2 02/13] PCI: prevent duplicate slot names

* Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>:
> Alex Chiang wrote:
>> @@ -570,9 +571,17 @@ int pci_hp_register(struct hotplug_slot *slot, struct pci_bus *bus, int slot_nr,
>>  		return -EINVAL;
>>  	}
>>  -	/* Check if we have already registered a slot with the same name. */
>> -	if (get_slot_from_name(name))
>> -		return -EEXIST;
>> +	/*
>> +	 * If we find a tmp_slot here, it means that another slot
>> +	 * driver has already created a pci_slot for this device.
>> +	 * We care (below) if the existing slot has a different name from
>> +	 * the new name that this particular hotplug driver is requesting.
>> +	 */
>> +	dev = pci_get_slot(bus, PCI_DEVFN(slot_nr, 0));
>> +	if (dev && dev->slot) {
>> +		tmp_slot = dev->slot;
>> +		pci_dev_put(dev);
>> +	}
>>
>
> I have two comments here.
>
> (1) I think the reference counter of the device will be leaked if
> (dev == NULL) && (dev->slot != NULL). We need pci_dev_put() whenever
> dev is not NULL.

You're right, thank you.

[one day, I _will_ learn how to get refcounting correct. :-/]

> (2) When the slot is empty, the 'dev' will be always NULL. Therefore,
> 'tmp_slot' will be always NULL on the empty slot here. Because of
> this, the following code to rename the slot will not work on the
> empty slot, I think.

Ok, I was trying to avoid creating a new interface called
"pci_find_phys_slot()" or something similar, but I think we need
it, and it will fix this issue.

Thanks again for the review.

/ac

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