From db89960e50f45274c07dc60926b5a49489b8a7a0 Mon Sep 17 00:00:00 2001 From: Michael Grzeschik Date: Wed, 12 Sep 2012 14:58:04 +0300 Subject: [PATCH] usb: chipidea: udc: don't stall endpoint if request list is empty in isr_tr_complete_low When attaching an imx28 or imx53 in USB gadget mode to a Windows host and starting a rndis connection we see this message every 4-10 seconds: g_ether gadget: high speed config #2: RNDIS Analysis shows that each time this message is printed, the rndis connection is re-establish due to a reset because of a stalled endpoint (ep 0, dir 1). The endpoint is stalled because the reqeust complete bit on that endpoint is set, but in isr_tr_complete_low() the endpoint request list (mEp->qh.queue) is empty. This patch removed this check, because the code doesn't take the following situation into account: The loop over all endpoints in isr_tr_complete_handler() will call ep_nuke() on both ep0/dir0 and ep/dir1 in the first loop. Pending reqeusts will be flushed and completed here. There seems to be a race condition, the request is nuked, but the request complete bit will be set, too. The subsequent check (in ep0/dir1's loop cycle) for endpoint request list (mEp->qh.queue) empty will fail. Both other mainline chipidea drivers (mv_udc_core.c and fsl_udc_core.c) don't have this check. Cc: stable Signed-off-by: Michael Grzeschik Signed-off-by: Marc Kleine-Budde Signed-off-by: Alexander Shishkin Signed-off-by: Greg Kroah-Hartman --- drivers/usb/chipidea/udc.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c index 2d8b609..d214448 100644 --- a/drivers/usb/chipidea/udc.c +++ b/drivers/usb/chipidea/udc.c @@ -771,10 +771,7 @@ __acquires(mEp->lock) { struct ci13xxx_req *mReq, *mReqTemp; struct ci13xxx_ep *mEpTemp = mEp; - int uninitialized_var(retval); - - if (list_empty(&mEp->qh.queue)) - return -EINVAL; + int retval = 0; list_for_each_entry_safe(mReq, mReqTemp, &mEp->qh.queue, queue) { -- 2.7.4