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

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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>
This commit is contained in:
Bin Liu 2016-05-31 10:05:04 -05:00 committed by Greg Kroah-Hartman
parent b580121222
commit dbac5d07d1
1 changed files with 7 additions and 1 deletions
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8
drivers/usb/musb/musb_host.c
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@ -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);