From: Bjorn Helgaas <bhelgaas@google.com>
Date: Tue, 24 Sep 2013 21:14:57 +0000 (-0600)
Subject: PCI: Document reason for using pci_is_root_bus()
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=77a0dfcd8a4d9a93a21c8be56eaeb65cd69b351d;p=linux-beck.git

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 <bhelgaas@google.com>
---

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)
 {