From 77a0dfcd8a4d9a93a21c8be56eaeb65cd69b351d Mon Sep 17 00:00:00 2001
From: Bjorn Helgaas <bhelgaas@google.com>
Date: Tue, 24 Sep 2013 15:14:57 -0600
Subject: 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>
---
include/linux/pci.h | 4 ++++
1 file changed, 4 insertions(+)
(limited to 'include/linux/pci.h')
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 197e2d21f2c..d3a888ae4b2 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)
{
--
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