USB: add a "remove hardware" sysfs attribute
This patch (as1297) adds a "remove" attribute to each USB device's
directory in sysfs. Writing to this attribute causes the device to be
deconfigured (the same as writing 0 to the "bConfigurationValue"
attribute) and then tells the hub driver to disable the device's
upstream port. The device remains locked during these activities so
there is no possibility of it getting reconfigured in between. The
port will remain disabled until after the device is unplugged.
The purpose of this is to provide a means for user programs to imitate
the "Safely remove hardware" applet in Windows. Some devices do
expect their ports to be disabled before they are unplugged, and they
provide visual feedback to users indicating when they can safely be
unplugged.
The security implications are minimal. Writing to the "remove"
attribute is no more dangerous than writing to the
"bConfigurationValue" attribute.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: David Zeuthen <davidz@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 708c638..5413d71 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -60,6 +60,8 @@
status change */
unsigned long busy_bits[1]; /* ports being reset or
resumed */
+ unsigned long removed_bits[1]; /* ports with a "removed"
+ device present */
#if USB_MAXCHILDREN > 31 /* 8*sizeof(unsigned long) - 1 */
#error event_bits[] is too short!
#endif
@@ -635,6 +637,33 @@
kick_khubd(hub);
}
+/**
+ * usb_remove_device - disable a device's port on its parent hub
+ * @udev: device to be disabled and removed
+ * Context: @udev locked, must be able to sleep.
+ *
+ * After @udev's port has been disabled, khubd is notified and it will
+ * see that the device has been disconnected. When the device is
+ * physically unplugged and something is plugged in, the events will
+ * be received and processed normally.
+ */
+int usb_remove_device(struct usb_device *udev)
+{
+ struct usb_hub *hub;
+ struct usb_interface *intf;
+
+ if (!udev->parent) /* Can't remove a root hub */
+ return -EINVAL;
+ hub = hdev_to_hub(udev->parent);
+ intf = to_usb_interface(hub->intfdev);
+
+ usb_autopm_get_interface(intf);
+ set_bit(udev->portnum, hub->removed_bits);
+ hub_port_logical_disconnect(hub, udev->portnum);
+ usb_autopm_put_interface(intf);
+ return 0;
+}
+
enum hub_activation_type {
HUB_INIT, HUB_INIT2, HUB_INIT3,
HUB_POST_RESET, HUB_RESUME, HUB_RESET_RESUME,
@@ -730,6 +759,13 @@
USB_PORT_FEAT_C_ENABLE);
}
+ /* We can forget about a "removed" device when there's a
+ * physical disconnect or the connect status changes.
+ */
+ if (!(portstatus & USB_PORT_STAT_CONNECTION) ||
+ (portchange & USB_PORT_STAT_C_CONNECTION))
+ clear_bit(port1, hub->removed_bits);
+
if (!udev || udev->state == USB_STATE_NOTATTACHED) {
/* Tell khubd to disconnect the device or
* check for a new connection
@@ -2965,6 +3001,13 @@
usb_disconnect(&hdev->children[port1-1]);
clear_bit(port1, hub->change_bits);
+ /* We can forget about a "removed" device when there's a physical
+ * disconnect or the connect status changes.
+ */
+ if (!(portstatus & USB_PORT_STAT_CONNECTION) ||
+ (portchange & USB_PORT_STAT_C_CONNECTION))
+ clear_bit(port1, hub->removed_bits);
+
if (portchange & (USB_PORT_STAT_C_CONNECTION |
USB_PORT_STAT_C_ENABLE)) {
status = hub_port_debounce(hub, port1);
@@ -2978,8 +3021,11 @@
}
}
- /* Return now if debouncing failed or nothing is connected */
- if (!(portstatus & USB_PORT_STAT_CONNECTION)) {
+ /* Return now if debouncing failed or nothing is connected or
+ * the device was "removed".
+ */
+ if (!(portstatus & USB_PORT_STAT_CONNECTION) ||
+ test_bit(port1, hub->removed_bits)) {
/* maybe switch power back on (e.g. root hub was reset) */
if ((wHubCharacteristics & HUB_CHAR_LPSM) < 2