1 files changed, 40 insertions, 42 deletions

diff --git a/drivers/usb/host/ehci-q.c b/drivers/usb/host/ehci-q.c
index 5d6bc624c96..9bf3c0d983c 100644
--- a/drivers/usb/host/ehci-q.c
+++ b/drivers/usb/host/ehci-q.c
@@ -1231,6 +1231,8 @@ static void start_unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh)
 
 	prev->hw->hw_next = qh->hw->hw_next;
 	prev->qh_next = qh->qh_next;
+	if (ehci->qh_scan_next == qh)
+		ehci->qh_scan_next = qh->qh_next.qh;
 	wmb ();
 
 	/* If the controller isn't running, we don't have to wait for it */
@@ -1256,53 +1258,49 @@ static void scan_async (struct ehci_hcd *ehci)
 	struct ehci_qh		*qh;
 	enum ehci_timer_action	action = TIMER_IO_WATCHDOG;
 
-	ehci->stamp = ehci_readl(ehci, &ehci->regs->frame_index);
 	timer_action_done (ehci, TIMER_ASYNC_SHRINK);
-rescan:
 	stopped = !HC_IS_RUNNING(ehci_to_hcd(ehci)->state);
-	qh = ehci->async->qh_next.qh;
-	if (likely (qh != NULL)) {
-		do {
-			/* clean any finished work for this qh */
-			if (!list_empty(&qh->qtd_list) && (stopped ||
-					qh->stamp != ehci->stamp)) {
-				int temp;
-
-				/* unlinks could happen here; completion
-				 * reporting drops the lock.  rescan using
-				 * the latest schedule, but don't rescan
-				 * qhs we already finished (no looping)
-				 * unless the controller is stopped.
-				 */
-				qh = qh_get (qh);
-				qh->stamp = ehci->stamp;
-				temp = qh_completions (ehci, qh);
-				if (qh->needs_rescan)
-					unlink_async(ehci, qh);
-				qh_put (qh);
-				if (temp != 0) {
-					goto rescan;
-				}
-			}
 
-			/* unlink idle entries, reducing DMA usage as well
-			 * as HCD schedule-scanning costs.  delay for any qh
-			 * we just scanned, there's a not-unusual case that it
-			 * doesn't stay idle for long.
-			 * (plus, avoids some kind of re-activation race.)
+	ehci->qh_scan_next = ehci->async->qh_next.qh;
+	while (ehci->qh_scan_next) {
+		qh = ehci->qh_scan_next;
+		ehci->qh_scan_next = qh->qh_next.qh;
+ rescan:
+		/* clean any finished work for this qh */
+		if (!list_empty(&qh->qtd_list)) {
+			int temp;
+
+			/*
+			 * Unlinks could happen here; completion reporting
+			 * drops the lock.  That's why ehci->qh_scan_next
+			 * always holds the next qh to scan; if the next qh
+			 * gets unlinked then ehci->qh_scan_next is adjusted
+			 * in start_unlink_async().
 			 */
-			if (list_empty(&qh->qtd_list)
-					&& qh->qh_state == QH_STATE_LINKED) {
-				if (!ehci->reclaim && (stopped ||
-					((ehci->stamp - qh->stamp) & 0x1fff)
-						>= EHCI_SHRINK_FRAMES * 8))
-					start_unlink_async(ehci, qh);
-				else
-					action = TIMER_ASYNC_SHRINK;
-			}
+			qh = qh_get(qh);
+			temp = qh_completions(ehci, qh);
+			if (qh->needs_rescan)
+				unlink_async(ehci, qh);
+			qh->unlink_time = jiffies + EHCI_SHRINK_JIFFIES;
+			qh_put(qh);
+			if (temp != 0)
+				goto rescan;
+		}
 
-			qh = qh->qh_next.qh;
-		} while (qh);
+		/* unlink idle entries, reducing DMA usage as well
+		 * as HCD schedule-scanning costs.  delay for any qh
+		 * we just scanned, there's a not-unusual case that it
+		 * doesn't stay idle for long.
+		 * (plus, avoids some kind of re-activation race.)
+		 */
+		if (list_empty(&qh->qtd_list)
+				&& qh->qh_state == QH_STATE_LINKED) {
+			if (!ehci->reclaim && (stopped ||
+					time_after_eq(jiffies, qh->unlink_time)))
+				start_unlink_async(ehci, qh);
+			else
+				action = TIMER_ASYNC_SHRINK;
+		}
 	}
 	if (action == TIMER_ASYNC_SHRINK)
 		timer_action (ehci, TIMER_ASYNC_SHRINK);