usbhid: prevent deadlock during timeout
On some HCDs usb_unlink_urb() can directly call the
completion handler. That limits the spinlocks that can
be taken in the handler to locks not held while calling
usb_unlink_urb()
To prevent a race with resubmission, this patch exposes
usbcore's infrastructure for blocking submission, uses it
and so drops the lock without causing a race in usbhid.
Signed-off-by: Oliver Neukum <oneukum@suse.de>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
index 5bf91db..4bbb883 100644
--- a/drivers/hid/usbhid/hid-core.c
+++ b/drivers/hid/usbhid/hid-core.c
@@ -399,6 +399,16 @@
* Output interrupt completion handler.
*/
+static int irq_out_pump_restart(struct hid_device *hid)
+{
+ struct usbhid_device *usbhid = hid->driver_data;
+
+ if (usbhid->outhead != usbhid->outtail)
+ return hid_submit_out(hid);
+ else
+ return -1;
+}
+
static void hid_irq_out(struct urb *urb)
{
struct hid_device *hid = urb->context;
@@ -428,7 +438,7 @@
else
usbhid->outtail = (usbhid->outtail + 1) & (HID_OUTPUT_FIFO_SIZE - 1);
- if (usbhid->outhead != usbhid->outtail && !hid_submit_out(hid)) {
+ if (!irq_out_pump_restart(hid)) {
/* Successfully submitted next urb in queue */
spin_unlock_irqrestore(&usbhid->lock, flags);
return;
@@ -443,6 +453,15 @@
/*
* Control pipe completion handler.
*/
+static int ctrl_pump_restart(struct hid_device *hid)
+{
+ struct usbhid_device *usbhid = hid->driver_data;
+
+ if (usbhid->ctrlhead != usbhid->ctrltail)
+ return hid_submit_ctrl(hid);
+ else
+ return -1;
+}
static void hid_ctrl(struct urb *urb)
{
@@ -476,7 +495,7 @@
else
usbhid->ctrltail = (usbhid->ctrltail + 1) & (HID_CONTROL_FIFO_SIZE - 1);
- if (usbhid->ctrlhead != usbhid->ctrltail && !hid_submit_ctrl(hid)) {
+ if (!ctrl_pump_restart(hid)) {
/* Successfully submitted next urb in queue */
spin_unlock(&usbhid->lock);
return;
@@ -535,11 +554,27 @@
* the queue is known to run
* but an earlier request may be stuck
* we may need to time out
- * no race because this is called under
+ * no race because the URB is blocked under
* spinlock
*/
- if (time_after(jiffies, usbhid->last_out + HZ * 5))
+ if (time_after(jiffies, usbhid->last_out + HZ * 5)) {
+ usb_block_urb(usbhid->urbout);
+ /* drop lock to not deadlock if the callback is called */
+ spin_unlock(&usbhid->lock);
usb_unlink_urb(usbhid->urbout);
+ spin_lock(&usbhid->lock);
+ usb_unblock_urb(usbhid->urbout);
+ /*
+ * if the unlinking has already completed
+ * the pump will have been stopped
+ * it must be restarted now
+ */
+ if (!test_bit(HID_OUT_RUNNING, &usbhid->iofl))
+ if (!irq_out_pump_restart(hid))
+ set_bit(HID_OUT_RUNNING, &usbhid->iofl);
+
+
+ }
}
return;
}
@@ -583,11 +618,25 @@
* the queue is known to run
* but an earlier request may be stuck
* we may need to time out
- * no race because this is called under
+ * no race because the URB is blocked under
* spinlock
*/
- if (time_after(jiffies, usbhid->last_ctrl + HZ * 5))
+ if (time_after(jiffies, usbhid->last_ctrl + HZ * 5)) {
+ usb_block_urb(usbhid->urbctrl);
+ /* drop lock to not deadlock if the callback is called */
+ spin_unlock(&usbhid->lock);
usb_unlink_urb(usbhid->urbctrl);
+ spin_lock(&usbhid->lock);
+ usb_unblock_urb(usbhid->urbctrl);
+ /*
+ * if the unlinking has already completed
+ * the pump will have been stopped
+ * it must be restarted now
+ */
+ if (!test_bit(HID_CTRL_RUNNING, &usbhid->iofl))
+ if (!ctrl_pump_restart(hid))
+ set_bit(HID_CTRL_RUNNING, &usbhid->iofl);
+ }
}
}