Commit dbac5d07 authored May 31, 2016 by Bin Liu Committed by Greg Kroah-Hartman Jun 01, 2016

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: Max Uvarov <muvarov@gmail.com>
Tested-by: Yegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent b5801212

drivers/usb/musb/musb_host.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -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);