Re: [PATCH] lspci: Skip scanning empty slot in sysfs_fill_slots

[Zheng Huai Cheng <zhenghch@linux.vnet.ibm.com>]

On Tue, 2013-10-29 at 13:09 +0100, Martin Mares wrote:
> Hello!
> 
> > When slot is empty, lspci will report "pcilib: sysfs_fill_slots:
> > Couldn't parse entry address 0000:01",this is because address entry will
> > only contain domain and bus number when the slot is empty.
> > 
> > [root@uselp6 ~]# cat /sys/bus/pci/slots/U5802.001.RCHB059-P1-C7/address
> > 0000:01

> Is this behavior intentional?  It does not make much sense to me.
> 
> 				Have a nice fortnight
although I am not a expert in PCI, seems this related to PCI hotplug.
And I also found a description in kernel source code

"
Placeholder slots:
In most cases, @pci_bus, @slot_nr will be sufficient to uniquely
identify a slot. There is one notable exception - pSeries (rpaphp),
where the @slot_nr cannot be determined until a device is actually
inserted into the slot. In this scenario, the caller may pass -1 for
@slot_nr.The following semantics are imposed when the caller passes
@slot_nr == -1. First, we no longer check for an existing %struct
pci_slot, as there may be many slots with @slot_nr of -1.  The other
change in semantics is user-visible, which is the 'address' parameter
presented in sysfs will consist solely of a dddd:bb tuple, where dddd is
the PCI domain of the %struct pci_bus and bb is the bus number. In other
words, the devfn of the 'placeholder' slot will not be
displayed.                             
"

so when slots are empty in some cases, "address" solely contain dddd:bb
tuple. But lspci will originally assume address in dddd:dd:dd tuple. so
we should skip dddd:bb case in sysfs_fill_slots