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Subject[PATCH v4 07/12] PCI: Introduce /sys/bus/pci/rescan
Date
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>
---
Documentation/ABI/testing/sysfs-bus-pci | 9 +++++++++
drivers/pci/pci-driver.c | 1 +
drivers/pci/pci-sysfs.c | 29 +++++++++++++++++++++++++++++
drivers/pci/pci.h | 6 ++++++
4 files changed, 45 insertions(+), 0 deletions(-)
diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci
index e638e15..ea4aee2 100644
--- a/Documentation/ABI/testing/sysfs-bus-pci
+++ b/Documentation/ABI/testing/sysfs-bus-pci
@@ -41,6 +41,15 @@ Description:
for the device and attempt to bind to it. For example:
# echo "8086 10f5" > /sys/bus/pci/drivers/foo/new_id

+What: /sys/bus/pci/rescan
+Date: January 2009
+Contact: Linux PCI developers <linux-pci@vger.kernel.org>
+Description:
+ Writing a non-zero value to this attribute will
+ force a rescan of all PCI buses in the system, and
+ re-discover previously removed devices.
+ Depends on CONFIG_HOTPLUG.
+
What: /sys/bus/pci/devices/.../vpd
Date: February 2008
Contact: Ben Hutchings <bhutchings@solarflare.com>
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index a5f11ad..62ed864 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -973,6 +973,7 @@ struct bus_type pci_bus_type = {
.remove = pci_device_remove,
.shutdown = pci_device_shutdown,
.dev_attrs = pci_dev_attrs,
+ .bus_attrs = pci_bus_attrs,
.pm = PCI_PM_OPS_PTR,
};

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 1c89298..22dbc65 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -219,6 +219,35 @@ 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 (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ 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, NULL, bus_rescan_store),
+ __ATTR_NULL
+};
+#endif
+
struct device_attribute pci_dev_attrs[] = {
__ATTR_RO(resource),
__ATTR_RO(vendor),
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 07c0aa5..6dea35f 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -136,6 +136,12 @@ extern int pcie_mch_quirk;
extern struct device_attribute pci_dev_attrs[];
extern struct device_attribute dev_attr_cpuaffinity;
extern struct device_attribute dev_attr_cpulistaffinity;
+#ifdef CONFIG_HOTPLUG
+extern struct bus_attribute pci_bus_attrs[];
+#else
+#define pci_bus_attrs NULL
+#endif
+

/**
* pci_match_one_device - Tell if a PCI device structure has a matching


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