caif-hsi: Remove deprecated create_singlethread_workqueue

alloc_workqueue replaces deprecated create_singlethread_workqueue().

A dedicated workqueue has been used since the workitems are being used
on a packet tx/rx path. Hence, WQ_MEM_RECLAIM has been set to guarantee
forward progress under memory pressure.

An ordered workqueue has been used since workitems &cfhsi->wake_up_work
and &cfhsi->wake_down_work cannot be run concurrently.

Calls to flush_workqueue() before destroy_workqueue() have been dropped
since destroy_workqueue() itself calls drain_workqueue() which flushes
repeatedly till the workqueue becomes empty.
Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/caif/caif_hsi.c

@@ -1201,7 +1201,7 @@ static int cfhsi_open(struct net_device *ndev)
 	clear_bit(CFHSI_AWAKE, &cfhsi->bits);
 
 	/* Create work thread. */
-	cfhsi->wq = create_singlethread_workqueue(cfhsi->ndev->name);
+	cfhsi->wq = alloc_ordered_workqueue(cfhsi->ndev->name, WQ_MEM_RECLAIM);
 	if (!cfhsi->wq) {
 		netdev_err(cfhsi->ndev, "%s: Failed to create work queue.\n",
 			__func__);
@@ -1267,9 +1267,6 @@ static int cfhsi_close(struct net_device *ndev)
 	/* going to shutdown driver */
 	set_bit(CFHSI_SHUTDOWN, &cfhsi->bits);
 
-	/* Flush workqueue */
-	flush_workqueue(cfhsi->wq);
-
 	/* Delete timers if pending */
 	del_timer_sync(&cfhsi->inactivity_timer);
 	del_timer_sync(&cfhsi->rx_slowpath_timer);