usb: musb: host: don't start next rx urb if current one failed

urb->status is set when endpoint csr RXSTALL, H_ERROR, DATAERROR or
INCOMPRX bit is set. Those bits mean a broken pipe, so don't start next
urb when any of these bits is set by checking urb->status.

To minimize the risk of regression, only do so for RX, until we have a
test case to understand the behavior of TX.

The patch fixes system freeze issue caused by repeatedly invoking RX ISR
while removing a usb uart device connected to a hub, in which case the
hub has no chance to report the disconnect event due to the kernel is
busy in processing the RX interrupt flooding.

Fix checkpatch complaint (qh != NULL) as while.
Reported-by: NMax Uvarov <muvarov@gmail.com>
Tested-by: NYegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: NBin Liu <b-liu@ti.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/musb/musb_host.c

@@ -434,7 +434,13 @@ static void musb_advance_schedule(struct musb *musb, struct urb *urb,
 		}
 	}
 
-	if (qh != NULL && qh->is_ready) {
+	/*
+	 * The pipe must be broken if current urb->status is set, so don't
+	 * start next urb.
+	 * TODO: to minimize the risk of regression, only check urb->status
+	 * for RX, until we have a test case to understand the behavior of TX.
+	 */
+	if ((!status || !is_in) && qh && qh->is_ready) {
 		dev_dbg(musb->controller, "... next ep%d %cX urb %p\n",
 		    hw_ep->epnum, is_in ? 'R' : 'T', next_urb(qh));
 		musb_start_urb(musb, is_in, qh);