PCI: Introduce /sys/bus/pci/devices/.../remove

This patch adds an attribute named "remove" to a PCI device's sysfs
directory.  Writing a non-zero value to this attribute will remove the PCI
device and any children of it.

Trent Piepho wrote the original implementation and documentation.

Thanks to Vegard Nossum for testing under kmemcheck and finding locking
issues with the sysfs interface.

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

1 files changed, 36 insertions, 0 deletions

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index be7468a5eb72..e16990ecc024 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -243,6 +243,39 @@ struct bus_attribute pci_bus_attrs[] = {
         __ATTR(rescan, (S_IWUSR|S_IWGRP), NULL, bus_rescan_store),
         __ATTR_NULL
 };
+
+static void remove_callback(struct device *dev)
+{
+        struct pci_dev *pdev = to_pci_dev(dev);
+
+        mutex_lock(&pci_remove_rescan_mutex);
+        pci_remove_bus_device(pdev);
+        mutex_unlock(&pci_remove_rescan_mutex);
+}
+
+static ssize_t
+remove_store(struct device *dev, struct device_attribute *dummy,
+             const char *buf, size_t count)
+{
+        int ret = 0;
+        unsigned long val;
+        struct pci_dev *pdev = to_pci_dev(dev);
+
+        if (strict_strtoul(buf, 0, &val) < 0)
+                return -EINVAL;
+
+        if (pci_is_root_bus(pdev->bus))
+                return -EBUSY;
+
+        /* An attribute cannot be unregistered by one of its own methods,
+         * so we have to use this roundabout approach.
+         */
+        if (val)
+                ret = device_schedule_callback(dev, remove_callback);
+        if (ret)
+                count = ret;
+        return count;
+}
 #endif
 
 struct device_attribute pci_dev_attrs[] = {
@@ -263,6 +296,9 @@ struct device_attribute pci_dev_attrs[] = {
         __ATTR(broken_parity_status,(S_IRUGO|S_IWUSR),
                 broken_parity_status_show,broken_parity_status_store),
         __ATTR(msi_bus, 0644, msi_bus_show, msi_bus_store),
+#ifdef CONFIG_HOTPLUG
+        __ATTR(remove, (S_IWUSR|S_IWGRP), NULL, remove_store),
+#endif
         __ATTR_NULL,
 };