HID: usbhid: improve handling of Clear-Halt and reset

This patch changes the way usbhid carries out Clear-Halt and reset.

Currently, after a Clear-Halt on the interrupt-IN endpoint, the driver
immediately restarts the interrupt URB, even if the Clear-Halt failed.
This doesn't work out well when the reason for the failure was that
the device was disconnected (when a low- or full-speed device is
connected through a hub to an EHCI controller, transfer errors caused
by disconnection are reported as stalls by the hub).  Instead now the
driver will attempt a reset after a failed Clear-Halt.

The way resets are carried out is also changed.  Now the driver will
call usb_queue_reset_device() instead of calling usb_reset_device()
directly.  This avoids a deadlock that would arise when a device is
unplugged: The hid_reset() routine runs as a workqueue item, a reset
attempt after the device has been unplugged will fail, failure will
cause usbhid to be unbound, and the disconnect routine will try to do
cancel_work_sync().  The usb_queue_reset_device() implementation is
carefully written to handle scenarios like this one properly.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
index 79cf503..80c5076 100644 (file)
--- a/drivers/hid/usbhid/hid-core.c
+++ b/drivers/hid/usbhid/hid-core.c
@@ -116,40 +116,24 @@ static void hid_reset(struct work_struct *work)
        struct usbhid_device *usbhid =
                container_of(work, struct usbhid_device, reset_work);
        struct hid_device *hid = usbhid->hid;
-       int rc = 0;
+       int rc;
 
        if (test_bit(HID_CLEAR_HALT, &usbhid->iofl)) {
                dev_dbg(&usbhid->intf->dev, "clear halt\n");
                rc = usb_clear_halt(hid_to_usb_dev(hid), usbhid->urbin->pipe);
                clear_bit(HID_CLEAR_HALT, &usbhid->iofl);
-               hid_start_in(hid);
-       }
-
-       else if (test_bit(HID_RESET_PENDING, &usbhid->iofl)) {
-               dev_dbg(&usbhid->intf->dev, "resetting device\n");
-               rc = usb_lock_device_for_reset(hid_to_usb_dev(hid), usbhid->intf);
                if (rc == 0) {
-                       rc = usb_reset_device(hid_to_usb_dev(hid));
-                       usb_unlock_device(hid_to_usb_dev(hid));
+                       hid_start_in(hid);
+               } else {
+                       dev_dbg(&usbhid->intf->dev,
+                                       "clear-halt failed: %d\n", rc);
+                       set_bit(HID_RESET_PENDING, &usbhid->iofl);
                }
-               clear_bit(HID_RESET_PENDING, &usbhid->iofl);
        }
 
-       switch (rc) {
-       case 0:
-               if (!test_bit(HID_IN_RUNNING, &usbhid->iofl))
-                       hid_io_error(hid);
-               break;
-       default:
-               hid_err(hid, "can't reset device, %s-%s/input%d, status %d\n",
-                       hid_to_usb_dev(hid)->bus->bus_name,
-                       hid_to_usb_dev(hid)->devpath,
-                       usbhid->ifnum, rc);
-               /* FALLTHROUGH */
-       case -EHOSTUNREACH:
-       case -ENODEV:
-       case -EINTR:
-               break;
+       if (test_bit(HID_RESET_PENDING, &usbhid->iofl)) {
+               dev_dbg(&usbhid->intf->dev, "resetting device\n");
+               usb_queue_reset_device(usbhid->intf);
        }
 }