Subject: Re: [PATCH 2/8] powerpc/pci: Don't scan empty slot

From: Gavin Shan <[email-masked]>
Date: Wed, 26 Nov 2014 10:57:24 +1100

On Wed, Nov 26, 2014 at 09:58:02AM +1100, Benjamin Herrenschmidt wrote:
>On Tue, 2014-11-25 at 09:49 +1100, Gavin Shan wrote:
>> In hotplug case, function pcibios_add_pci_devices() is called to
>> rescan the specified PCI bus, which possibly doesn't have any child
>> devices. Access to the PCI bus's child device node will cause kernel
>> crash without exception. The patch adds two more conditions to avoid
>> the kernel crash.
>> 
>> Signed-off-by: Gavin Shan <[email-masked]>
>> ---
>>  arch/powerpc/kernel/pci-hotplug.c | 5 +++--
>>  1 file changed, 3 insertions(+), 2 deletions(-)
>> 
>> diff --git a/arch/powerpc/kernel/pci-hotplug.c b/arch/powerpc/kernel/pci-hotplug.c
>> index 6e2b4e3..ea5513b 100644
>> --- a/arch/powerpc/kernel/pci-hotplug.c
>> +++ b/arch/powerpc/kernel/pci-hotplug.c
>> @@ -105,7 +105,7 @@ EXPORT_SYMBOL_GPL(pcibios_remove_pci_devices);
>>   * is how this routine differs from other, similar pcibios
>>   * routines.)
>>   */
>> -void pcibios_add_pci_devices(struct pci_bus * bus)
>> +void pcibios_add_pci_devices(struct pci_bus *bus)
>
>Unrelated whitespace change
>

I'll remove this change out of the patch.

Thanks,
Gavin

>>  {
>>  	int slotno, mode, pass, max;
>>  	struct pci_dev *dev;
>> @@ -120,7 +120,8 @@ void pcibios_add_pci_devices(struct pci_bus * bus)
>>  	if (mode == PCI_PROBE_DEVTREE) {
>>  		/* use ofdt-based probe */
>>  		of_rescan_bus(dn, bus);
>> -	} else if (mode == PCI_PROBE_NORMAL) {
>> +	} else if (mode == PCI_PROBE_NORMAL &&
>> +		   dn->child && PCI_DN(dn->child)) {
>>  		/*
>>  		 * Use legacy probe. In the partial hotplug case, we
>>  		 * probably have grandchildren devices unplugged. So
>
>