From 77a0dfcd8a4d9a93a21c8be56eaeb65cd69b351d Mon Sep 17 00:00:00 2001 From: Bjorn Helgaas Date: Tue, 24 Sep 2013 15:14:57 -0600 Subject: [PATCH] PCI: Document reason for using pci_is_root_bus() Some code assumes "bus->self == NULL" means the bus is a root bus. This adds a comment explaining why this is incorrect ("virtual" buses added for SR-IOV have "bus->self == NULL" but are not root buses). No functional change. Signed-off-by: Bjorn Helgaas --- include/linux/pci.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/include/linux/pci.h b/include/linux/pci.h index 197e2d21f2cb..d3a888ae4b2e 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -470,6 +470,10 @@ struct pci_bus { /* * Returns true if the pci bus is root (behind host-pci bridge), * false otherwise + * + * Some code assumes that "bus->self == NULL" means that bus is a root bus. + * This is incorrect because "virtual" buses added for SR-IOV (via + * virtfn_add_bus()) have "bus->self == NULL" but are not root buses. */ static inline bool pci_is_root_bus(struct pci_bus *pbus) { -- GitLab