xhci: handle stop endpoint command completion with endpoint in running state.

Handle race where a stop endpoint command fails with "context state error"
as hardware hasn't actually started the ring yet after a previous urb
cancellation completed and restarted the endpoint.
Flushing the doorbell write that restart the endpoint reduced these cases,
but didn't completely resolve them.

Check if the ring is running in the stop endpoint completion handler, and
issue a new stop endpoint command in this case.
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20210129130044.206855-24-mathias.nyman@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-ring.c

@@ -983,6 +983,7 @@ static void xhci_handle_cmd_stop_ep(struct xhci_hcd *xhci, int slot_id,
 	struct xhci_ep_ctx *ep_ctx;
 	struct xhci_td *td = NULL;
 	enum xhci_ep_reset_type reset_type;
+	struct xhci_command *command;
 
 	if (unlikely(TRB_TO_SUSPEND_PORT(le32_to_cpu(trb->generic.field[3])))) {
 		if (!xhci->devs[slot_id])
@@ -1029,6 +1030,18 @@ static void xhci_handle_cmd_stop_ep(struct xhci_hcd *xhci, int slot_id,
 			/* reset ep, reset handler cleans up cancelled tds */
 			xhci_handle_halted_endpoint(xhci, ep, 0, td, reset_type);
 			xhci_stop_watchdog_timer_in_irq(xhci, ep);
+			return;
+		case EP_STATE_RUNNING:
+			/* Race, HW handled stop ep cmd before ep was running */
+			command = xhci_alloc_command(xhci, false, GFP_ATOMIC);
+			if (!command)
+				xhci_stop_watchdog_timer_in_irq(xhci, ep);
+
+			mod_timer(&ep->stop_cmd_timer,
+				  jiffies + XHCI_STOP_EP_CMD_TIMEOUT * HZ);
+			xhci_queue_stop_endpoint(xhci, command, slot_id, ep_index, 0);
+			xhci_ring_cmd_db(xhci);
+
 			return;
 		default:
 			break;