PCI: Introduce /sys/bus/pci/rescan

This interface allows the user to force a rescan of all PCI buses
in system, and rediscover devices that have been removed earlier.

pci_bus_attrs implementation from Trent Piepho.

Thanks to Vegard Nossum for discovering locking issues with the
sysfs interface.

Cc: Trent Piepho <xyzzy@speakeasy.org>
Signed-off-by: Alex Chiang <achiang@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 60a8e5fec6c5..56c71e585f3d 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1228,13 +1228,13 @@ unsigned int __devinit pci_rescan_bus(struct pci_bus *bus)
 
         max = pci_scan_child_bus(bus);
 
-        up_read(&pci_bus_sem);
+        down_read(&pci_bus_sem);
         list_for_each_entry(dev, &bus->devices, bus_list)
                 if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE ||
                     dev->hdr_type == PCI_HEADER_TYPE_CARDBUS)
                         if (dev->subordinate)
                                 pci_bus_size_bridges(dev->subordinate);
-        down_read(&pci_bus_sem);
+        up_read(&pci_bus_sem);
 
         pci_bus_assign_resources(bus);
         pci_enable_bridges(bus);