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Commit 8f507ef5 authored by Alan Stern's avatar Alan Stern Committed by Jiri Kosina
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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: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
parent 79346d62

drivers/hid/usbhid/hid-core.c

+9 −25
Original line number Diff line number Diff line
@@ -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);

	}

}