linux-kernel - Re: [PATCH 0/4, v14] PCI, ACPI: Physical PCI slot objects

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Date:	Tue, 10 Jun 2008 12:12:26 +0900
From:	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>
To:	Alex Chiang <achiang@...com>,
	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>,
	jbarnes@...tuousgeek.org,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Matthew Wilcox <matthew@....cx>,
	Andrew Morton <akpm@...ux-foundation.org>,
	kristen.c.accardi@...el.com, greg@...ah.com, lenb@...nel.org,
	pbadari@...ibm.com, linux-pci@...r.kernel.org,
	pcihpd-discuss@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/4, v14] PCI, ACPI: Physical PCI slot objects

Kenji Kaneshige wrote:
> Alex Chiang wrote:
>> * Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>:

(snip.)

> Thank you for explanation. I understood.
> 
> But I have one concern about the behavior when pci slot driver is not
> loaded. My patch (a86161b3134465f) prevents the kernel trace dump
> because of duplicate kobject add that would happen in the following two
> cases, though (b) is not described in the header of the patch (sorry).
> 
>   (a) multiple driver attempt to handle the same slot.
> 
>   (b) one or more driver attempt to register multiple slots with the
>       same name (This can happen if broken platform assigns the same
>       slot number to multiple hotplug slots, for example).
> 
> With your patch, duplicate kobject add in case (b) is not prevented.
> That is my concern.
> 
> I made a below patch to prevent (b), please take a look. And could you
> please consider merging it to "[PATCH 2/3] Introduce pci_slot" in your
> latest series.
> 
> Thanks,
> Kenji Kaneshige
> 
> 
> ---
>  drivers/pci/hotplug/pci_hotplug_core.c |   16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> Index: 20080610/drivers/pci/hotplug/pci_hotplug_core.c
> ===================================================================
> --- 20080610.orig/drivers/pci/hotplug/pci_hotplug_core.c
> +++ 20080610/drivers/pci/hotplug/pci_hotplug_core.c
> @@ -555,6 +555,7 @@ int pci_hp_register(struct hotplug_slot 
>  {
>  	int result;
>  	struct pci_slot *pci_slot;
> +	struct hotplug_slot *tmp;
>  
>  	if (slot == NULL)
>  		return -ENODEV;
> @@ -567,6 +568,21 @@ int pci_hp_register(struct hotplug_slot 
>  	}
>  
>  	/*
> +	 * Prevent registering multiple hotplug slots with the same name.
> +	 */
> +	spin_lock(&pci_hotplug_slot_list_lock);
> +	list_for_each_entry(tmp, &pci_hotplug_slot_list, slot_list) {
> +		pci_slot = tmp->pci_slot;
> +		if (pci_slot->bus == bus && pci_slot->number == slot_nr)
> +			continue;
> +		if (!strcmp(tmp->name, slot->name)) {
> +			spin_unlock(&pci_hotplug_slot_list_lock);
> +			return -EEXIST;
> +		}
> +	}
> +	spin_unlock(&pci_hotplug_slot_list_lock);
> +
> +	/*
>  	 * No problems if we call this interface from both ACPI_PCI_SLOT
>  	 * driver and call it here again. If we've already created the
>  	 * pci_slot, the interface will simply bump the refcount.
> 
>

Please note that I made this patch against linux-next with your
latest three patches applied.

Thanks,
Kenji Kaneshige


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