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.
Reported-by: Max Uvarov <muvarov@xxxxxxxxx>
Tested-by: Yegor Yefremov <yegorslists@xxxxxxxxxxxxxx>
Signed-off-by: Bin Liu <b-liu@xxxxxx>
---
drivers/usb/musb/musb_host.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
index 90c6115..ecbd8bb 100644
--- a/drivers/usb/musb/musb_host.c
+++ b/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 != NULL && 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);
--
1.9.1
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