Re: [PATCH v8 30/45] powerpc/pci: Delay populating pdn

On 02/17/2016 02:44 PM, Gavin Shan wrote:

The pdn (struct pci_dn) instances are allocated from memblock or
bootmem when creating PCI controller (hoses) in setup_arch(). PCI
hotplug, which will be supported by proceeding patches, releases
PCI device nodes and their corresponding pdn on unplugging event.
The memory chunks for pdn instances allocated from memblock or
bootmem are hard to reused after being released.

This delays creating pdn by pci_devs_phb_init() from setup_arch()
to core_initcall() so that they are allocated from slab. The memory
consumed by pdn can be released to system without problem during
PCI unplugging time. It indicates that pci_dn is unavailable in
setup_arch() and the the fixup on pdn (like AGP's) can't be carried
out that time. We have to do that in ppc_md.pcibios_root_bridge_prepare()
on maple/pasemi/powermac platforms where/when the pdn is available.

At the mean while, the EEH device is created when pdn is populated,
meaning pdn and EEH device have same life cycle. In turn, we needn't
call eeh_dev_init() to create EEH device explicitly.

Signed-off-by: Gavin Shan <redacted>

Uff. It would not hurt to mention that  pcibios_root_bridge_prepare is 
called from subsys_initcall() which is executed after core_initcall() so 
the code flow does not change.

Have you checked if there is anything in between 
core_initcall(pci_devs_phb_init) and subsys_initcall(pcibios_init) which 
might need device tree nodes? For example, subsys_initcall(pcibios_init) 
calls (eventually) pnv_pci_ioda_fixup(), if we are unlucky and 
pcibios_init() (and therefore pnv_pci_ioda_fixup() or what pseries/others 
do) is called before pcibios_init() - won't we crash or something?




-- 
Alexey