From: Alan Stern Date: Fri, 31 Jul 2009 14:40:22 +0000 (-0400) Subject: USB: EHCI: fix two new bugs related to Clear-TT-Buffer X-Git-Tag: v2.6.31-rc6~35^2~5 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=7a0f0d951273eee889c2441846842348ebc00a2a;p=platform%2Fkernel%2Flinux-stable.git USB: EHCI: fix two new bugs related to Clear-TT-Buffer This patch (as1273) fixes two(!) bugs introduced by the new Clear-TT-Buffer implementation in ehci-hcd. It is now possible for an idle QH to have some URBs on its queue -- this will happen if a Clear-TT-Buffer is pending for the QH's endpoint. Consequently we should not issue a warning when someone tries to unlink an URB from an idle QH; instead we should process the request immediately. The refcounts for QHs could get messed up, because submit_async() would increment the refcount when calling qh_link_async() and qh_link_async() would then refuse to link the QH into the schedule if a Clear-TT-Buffer was pending. Instead we should increment the refcount only when the QH actually is added to the schedule. The current code tries to be clever by leaving the refcount alone if an unlink is immediately followed by a relink; the patch changes this to an unconditional decrement and increment (although they occur in the opposite order). Signed-off-by: Alan Stern CC: David Brownell Tested-by: Manuel Lauss Tested-by: Matthijs Kooijman Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c index 7d03549..11c627c 100644 --- a/drivers/usb/host/ehci-hcd.c +++ b/drivers/usb/host/ehci-hcd.c @@ -903,7 +903,8 @@ static int ehci_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status) /* already started */ break; case QH_STATE_IDLE: - WARN_ON(1); + /* QH might be waiting for a Clear-TT-Buffer */ + qh_completions(ehci, qh); break; } break; diff --git a/drivers/usb/host/ehci-q.c b/drivers/usb/host/ehci-q.c index 9a13847..b273805 100644 --- a/drivers/usb/host/ehci-q.c +++ b/drivers/usb/host/ehci-q.c @@ -940,6 +940,7 @@ static void qh_link_async (struct ehci_hcd *ehci, struct ehci_qh *qh) head->qh_next.qh = qh; head->hw_next = dma; + qh_get(qh); qh->xacterrs = QH_XACTERR_MAX; qh->qh_state = QH_STATE_LINKED; /* qtd completions reported later by interrupt */ @@ -1080,7 +1081,7 @@ submit_async ( * the HC and TT handle it when the TT has a buffer ready. */ if (likely (qh->qh_state == QH_STATE_IDLE)) - qh_link_async (ehci, qh_get (qh)); + qh_link_async(ehci, qh); done: spin_unlock_irqrestore (&ehci->lock, flags); if (unlikely (qh == NULL)) @@ -1115,8 +1116,6 @@ static void end_unlink_async (struct ehci_hcd *ehci) && HC_IS_RUNNING (ehci_to_hcd(ehci)->state)) qh_link_async (ehci, qh); else { - qh_put (qh); // refcount from async list - /* it's not free to turn the async schedule on/off; leave it * active but idle for a while once it empties. */ @@ -1124,6 +1123,7 @@ static void end_unlink_async (struct ehci_hcd *ehci) && ehci->async->qh_next.qh == NULL) timer_action (ehci, TIMER_ASYNC_OFF); } + qh_put(qh); /* refcount from async list */ if (next) { ehci->reclaim = NULL;