Re: [PATCH 2.6.26] PCI: refuse to re-add a device to a bus upon pci_scan_child_bus()

From: eran liberty
Date: Tue Jul 22 2008 - 04:21:27 EST

> I think this is your real problem, that you're rescanning the entire
> bus. I don't think that's the route we'd recommend taking.

My stating point was that I have loaded a new design into a
programmable device which sits on the pci device. The new design can
implement numerous pci devices or non at all. I can think of an easy
way (or clean one) to scan only the programmable device. Scanning the
whole bus seemed reasonable.

> Why don't you call pci_scan_slot() instead? You won't get the benefit of
> pcibios_fixup_bus(), but I'm not convinced that's safe to call on a bus
> that's already been scanned.

As said its not exactly a slot its more like a regular pci device that
someone suddenly welded into the pci bus. Its not a hotplug as well,
and I do not want to give up on the pcibios_fixup_bus()

As it is, with my patch applied i successfully go over the bus and
remove my own devices before I reprogram the
programmable device.

while ((dev = pci_get_device(PCI_VENDOR_ID_MYCOMP,PCI_DEVICE_ID_MYDEV,NULL))
!= NULL) {

Load a new design into it.

Then scan the entire bus and add the newly discovered devices.

bus = null;
while ((bus = pci_find_next_bus(bus)) != NULL) {

As seen here, this sequence of instructions seems very intuitive. It
will fail without the patch upon pci_bus_add_devices().

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