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powerpc/pci: Don't scan empty slot 

In hotplug case, function pci_add_pci_devices() is called to rescan
the specified PCI bus, which might not have any child devices. Access
to the PCI bus's child device node will cause kernel crash without
exception.

This adds one more check to skip scanning PCI bus that doesn't have
any subordinate devices from device-tree, in order to avoid kernel
crash.

Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Gavin Shan 2016-05-03 15:41:43 +10:00 committed by Michael Ellerman
parent cdddc577d9
commit 4a5954ed77
1 changed files with 2 additions and 1 deletions
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3
arch/powerpc/kernel/pci-hotplug.c
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@ -120,7 +120,8 @@ void pci_hp_add_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