USB: whci-hcd: make endpoint_reset method async

usb_hcd_endpoint_reset() may be called in atomic context and must not
sleep.  So make whci-hcd's endpoint_reset() asynchronous.  URBs
submitted while the reset is in progress will be queued (on the std
list) and transfers will resume once the reset is complete.

Signed-off-by: David Vrabel <david.vrabel@csr.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/host/whci/asl.c

@@ -227,11 +227,21 @@ void scan_async_work(struct work_struct *work)
 	/*
 	 * Now that the ASL is updated, complete the removal of any
 	 * removed qsets.
+	 *
+	 * If the qset was to be reset, do so and reinsert it into the
+	 * ASL if it has pending transfers.
 	 */
 	spin_lock_irq(&whc->lock);
 
 	list_for_each_entry_safe(qset, t, &whc->async_removed_list, list_node) {
 		qset_remove_complete(whc, qset);
+		if (qset->reset) {
+			qset_reset(whc, qset);
+			if (!list_empty(&qset->stds)) {
+				asl_qset_insert_begin(whc, qset);
+				queue_work(whc->workqueue, &whc->async_work);
+			}
+		}
 	}
 
 	spin_unlock_irq(&whc->lock);
@@ -267,7 +277,7 @@ int asl_urb_enqueue(struct whc *whc, struct urb *urb, gfp_t mem_flags)
 	else
 		err = qset_add_urb(whc, qset, urb, GFP_ATOMIC);
 	if (!err) {
-		if (!qset->in_sw_list)
+		if (!qset->in_sw_list && !qset->remove)
 			asl_qset_insert_begin(whc, qset);
 	} else
 		usb_hcd_unlink_urb_from_ep(&whc->wusbhc.usb_hcd, urb);

drivers/usb/host/whci/hcd.c

@@ -192,19 +192,23 @@ static void whc_endpoint_reset(struct usb_hcd *usb_hcd,
 	struct wusbhc *wusbhc = usb_hcd_to_wusbhc(usb_hcd);
 	struct whc *whc = wusbhc_to_whc(wusbhc);
 	struct whc_qset *qset;
+	unsigned long flags;
+
+	spin_lock_irqsave(&whc->lock, flags);
 
 	qset = ep->hcpriv;
 	if (qset) {
 		qset->remove = 1;
+		qset->reset = 1;
 
 		if (usb_endpoint_xfer_bulk(&ep->desc)
 		    || usb_endpoint_xfer_control(&ep->desc))
 			queue_work(whc->workqueue, &whc->async_work);
 		else
 			queue_work(whc->workqueue, &whc->periodic_work);
-
-		qset_reset(whc, qset);
 	}
+
+	spin_unlock_irqrestore(&whc->lock, flags);
 }
 
 

drivers/usb/host/whci/pzl.c

@@ -255,11 +255,21 @@ void scan_periodic_work(struct work_struct *work)
 	/*
 	 * Now that the PZL is updated, complete the removal of any
 	 * removed qsets.
+	 *
+	 * If the qset was to be reset, do so and reinsert it into the
+	 * PZL if it has pending transfers.
 	 */
 	spin_lock_irq(&whc->lock);
 
 	list_for_each_entry_safe(qset, t, &whc->periodic_removed_list, list_node) {
 		qset_remove_complete(whc, qset);
+		if (qset->reset) {
+			qset_reset(whc, qset);
+			if (!list_empty(&qset->stds)) {
+				qset_insert_in_sw_list(whc, qset);
+				queue_work(whc->workqueue, &whc->periodic_work);
+			}
+		}
 	}
 
 	spin_unlock_irq(&whc->lock);
@@ -295,7 +305,7 @@ int pzl_urb_enqueue(struct whc *whc, struct urb *urb, gfp_t mem_flags)
 	else
 		err = qset_add_urb(whc, qset, urb, GFP_ATOMIC);
 	if (!err) {
-		if (!qset->in_sw_list)
+		if (!qset->in_sw_list && !qset->remove)
 			qset_insert_in_sw_list(whc, qset);
 	} else
 		usb_hcd_unlink_urb_from_ep(&whc->wusbhc.usb_hcd, urb);

drivers/usb/host/whci/qset.c

@@ -103,7 +103,6 @@ static void qset_fill_qh(struct whc_qset *qset, struct urb *urb)
 void qset_clear(struct whc *whc, struct whc_qset *qset)
 {
 	qset->td_start = qset->td_end = qset->ntds = 0;
-	qset->remove = 0;
 
 	qset->qh.link = cpu_to_le32(QH_LINK_NTDS(8) | QH_LINK_T);
 	qset->qh.status = qset->qh.status & QH_STATUS_SEQ_MASK;
@@ -125,7 +124,7 @@ void qset_clear(struct whc *whc, struct whc_qset *qset)
  */
 void qset_reset(struct whc *whc, struct whc_qset *qset)
 {
-	wait_for_completion(&qset->remove_complete);
+	qset->reset = 0;
 
 	qset->qh.status &= ~QH_STATUS_SEQ_MASK;
 	qset->qh.cur_window = cpu_to_le32((1 << qset->max_burst) - 1);
@@ -156,6 +155,7 @@ struct whc_qset *get_qset(struct whc *whc, struct urb *urb,
 
 void qset_remove_complete(struct whc *whc, struct whc_qset *qset)
 {
+	qset->remove = 0;
 	list_del_init(&qset->list_node);
 	complete(&qset->remove_complete);
 }

drivers/usb/host/whci/whci-hc.h

@@ -264,6 +264,7 @@ struct whc_qset {
 	unsigned in_sw_list:1;
 	unsigned in_hw_list:1;
 	unsigned remove:1;
+	unsigned reset:1;
 	struct urb *pause_after_urb;
 	struct completion remove_complete;
 	int max_burst;