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, 26 insertions, 0 deletions

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index ec7a175dcbaf..be7468a5eb72 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -219,6 +219,32 @@ msi_bus_store(struct device *dev, struct device_attribute *attr,
         return count;
 }
 
+#ifdef CONFIG_HOTPLUG
+static DEFINE_MUTEX(pci_remove_rescan_mutex);
+static ssize_t bus_rescan_store(struct bus_type *bus, const char *buf,
+                                size_t count)
+{
+        unsigned long val;
+        struct pci_bus *b = NULL;
+
+        if (strict_strtoul(buf, 0, &val) < 0)
+                return -EINVAL;
+
+        if (val) {
+                mutex_lock(&pci_remove_rescan_mutex);
+                while ((b = pci_find_next_bus(b)) != NULL)
+                        pci_rescan_bus(b);
+                mutex_unlock(&pci_remove_rescan_mutex);
+        }
+        return count;
+}
+
+struct bus_attribute pci_bus_attrs[] = {
+        __ATTR(rescan, (S_IWUSR|S_IWGRP), NULL, bus_rescan_store),
+        __ATTR_NULL
+};
+#endif
+
 struct device_attribute pci_dev_attrs[] = {
         __ATTR_RO(resource),
         __ATTR_RO(vendor),