USB: make ehci driver use a kref instead of an atomic_t

drivers/usb/host/ehci-hcd.c

@@ -965,7 +965,7 @@ ehci_endpoint_disable (struct usb_hcd *hcd, struct hcd_dev *dev, int ep)
 		goto rescan;
 	case QH_STATE_IDLE:		/* fully unlinked */
 		if (list_empty (&qh->qtd_list)) {
-			qh_put (ehci, qh);
+			qh_put (qh);
 			break;
 		}
 		/* else FALL THROUGH */

drivers/usb/host/ehci-mem.c

@@ -87,6 +87,22 @@ static inline void ehci_qtd_free (struct ehci_hcd *ehci, struct ehci_qtd *qtd)
 }
 
 
+static void qh_destroy (struct kref *kref)
+{
+	struct ehci_qh *qh = container_of(kref, struct ehci_qh, kref);
+	struct ehci_hcd *ehci = qh->ehci;
+
+	/* clean qtds first, and know this is not linked */
+	if (!list_empty (&qh->qtd_list) || qh->qh_next.ptr) {
+		ehci_dbg (ehci, "unused qh not empty!\n");
+		BUG ();
+	}
+	if (qh->dummy)
+		ehci_qtd_free (ehci, qh->dummy);
+	usb_put_dev (qh->dev);
+	dma_pool_free (ehci->qh_pool, qh, qh->qh_dma);
+}
+
 static struct ehci_qh *ehci_qh_alloc (struct ehci_hcd *ehci, int flags)
 {
 	struct ehci_qh		*qh;
@@ -98,7 +114,8 @@ static struct ehci_qh *ehci_qh_alloc (struct ehci_hcd *ehci, int flags)
 		return qh;
 
 	memset (qh, 0, sizeof *qh);
-	atomic_set (&qh->refcount, 1);
+	kref_init(&qh->kref, qh_destroy);
+	qh->ehci = ehci;
 	qh->qh_dma = dma;
 	// INIT_LIST_HEAD (&qh->qh_list);
 	INIT_LIST_HEAD (&qh->qtd_list);
@@ -114,25 +131,15 @@ static struct ehci_qh *ehci_qh_alloc (struct ehci_hcd *ehci, int flags)
 }
 
 /* to share a qh (cpu threads, or hc) */
-static inline struct ehci_qh *qh_get (/* ehci, */ struct ehci_qh *qh)
+static inline struct ehci_qh *qh_get (struct ehci_qh *qh)
 {
-	atomic_inc (&qh->refcount);
+	kref_get(&qh->kref);
 	return qh;
 }
 
-static void qh_put (struct ehci_hcd *ehci, struct ehci_qh *qh)
+static inline void qh_put (struct ehci_qh *qh)
 {
-	if (!atomic_dec_and_test (&qh->refcount))
-		return;
-	/* clean qtds first, and know this is not linked */
-	if (!list_empty (&qh->qtd_list) || qh->qh_next.ptr) {
-		ehci_dbg (ehci, "unused qh not empty!\n");
-		BUG ();
-	}
-	if (qh->dummy)
-		ehci_qtd_free (ehci, qh->dummy);
-	usb_put_dev (qh->dev);
-	dma_pool_free (ehci->qh_pool, qh, qh->qh_dma);
+	kref_put(&qh->kref);
 }
 
 /*-------------------------------------------------------------------------*/
@@ -145,7 +152,7 @@ static void qh_put (struct ehci_hcd *ehci, struct ehci_qh *qh)
 static void ehci_mem_cleanup (struct ehci_hcd *ehci)
 {
 	if (ehci->async)
-		qh_put (ehci, ehci->async);
+		qh_put (ehci->async);
 	ehci->async = 0;
 
 	/* DMA consistent memory and pools */

drivers/usb/host/ehci-q.c

@@ -193,7 +193,7 @@ ehci_urb_done (struct ehci_hcd *ehci, struct urb *urb, struct pt_regs *regs)
 			/* ... update hc-wide periodic stats (for usbfs) */
 			hcd_to_bus (&ehci->hcd)->bandwidth_int_reqs--;
 		}
-		qh_put (ehci, qh);
+		qh_put (qh);
 	}
 
 	spin_lock (&urb->lock);
@@ -708,7 +708,7 @@ qh_make (
 	default:
  		dbg ("bogus dev %p speed %d", urb->dev, urb->dev->speed);
 done:
-		qh_put (ehci, qh);
+		qh_put (qh);
 		return 0;
 	}
 
@@ -951,7 +951,7 @@ static void end_unlink_async (struct ehci_hcd *ehci, struct pt_regs *regs)
 	// qh->hw_next = cpu_to_le32 (qh->qh_dma);
 	qh->qh_state = QH_STATE_IDLE;
 	qh->qh_next.qh = 0;
-	qh_put (ehci, qh);			// refcount from reclaim 
+	qh_put (qh);			// refcount from reclaim 
 
 	/* other unlink(s) may be pending (in QH_STATE_UNLINK_WAIT) */
 	next = qh->reclaim;
@@ -965,7 +965,7 @@ static void end_unlink_async (struct ehci_hcd *ehci, struct pt_regs *regs)
 			&& HCD_IS_RUNNING (ehci->hcd.state))
 		qh_link_async (ehci, qh);
 	else {
-		qh_put (ehci, qh);		// refcount from async list
+		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.
@@ -1067,7 +1067,7 @@ scan_async (struct ehci_hcd *ehci, struct pt_regs *regs)
 				qh = qh_get (qh);
 				qh->stamp = ehci->stamp;
 				temp = qh_completions (ehci, qh, regs);
-				qh_put (ehci, qh);
+				qh_put (qh);
 				if (temp != 0) {
 					goto rescan;
 				}

drivers/usb/host/ehci-sched.c

@@ -312,7 +312,7 @@ static void intr_deschedule (
 
 	do {
 		periodic_unlink (ehci, frame, qh);
-		qh_put (ehci, qh);
+		qh_put (qh);
 		frame += qh->period;
 	} while (frame < ehci->periodic_size);
 
@@ -355,7 +355,7 @@ static void intr_deschedule (
 
 	dbg ("descheduled qh %p, period = %d frame = %d count = %d, urbs = %d",
 		qh, qh->period, frame,
-		atomic_read (&qh->refcount), ehci->periodic_sched);
+		atomic_read (&qh->kref.refcount), ehci->periodic_sched);
 }
 
 static int check_period (
@@ -1846,7 +1846,7 @@ scan_periodic (struct ehci_hcd *ehci, struct pt_regs *regs)
 				modified = qh_completions (ehci, temp.qh, regs);
 				if (unlikely (list_empty (&temp.qh->qtd_list)))
 					intr_deschedule (ehci, temp.qh, 0);
-				qh_put (ehci, temp.qh);
+				qh_put (temp.qh);
 				break;
 			case Q_TYPE_FSTN:
 				/* for "save place" FSTNs, look at QH entries

drivers/usb/host/ehci.h

@@ -366,7 +366,8 @@ struct ehci_qh {
 	struct ehci_qtd		*dummy;
 	struct ehci_qh		*reclaim;	/* next to reclaim */
 
-	atomic_t		refcount;
+	struct ehci_hcd		*ehci;
+	struct kref		kref;
 	unsigned		stamp;
 
 	u8			qh_state;