staging: octeon: Convert create_singlethread_workqueue()

With conccurency managed workqueues, use of dedicated workqueues can
be replaced by system_wq. Drop cvm_oct_poll_queue by using system_wq.

There are multiple work items per cvm_oct_poll_queue (viz.
cvm_oct_rx_refill_work, port_periodic_work) and different
cvm_oct_poll_queues need not be be ordered. Hence, concurrency
can be increased by switching to system_wq.

All work items are sync canceled in cvm_oct_remove() so it
is guaranteed that no work is in flight by the time exit path runs.

Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/octeon/ethernet.c

@@ -86,10 +86,6 @@ int rx_napi_weight = 32;
 module_param(rx_napi_weight, int, 0444);
 MODULE_PARM_DESC(rx_napi_weight, "The NAPI WEIGHT parameter.");
 
-/*
- * cvm_oct_poll_queue - Workqueue for polling operations.
- */
-struct workqueue_struct *cvm_oct_poll_queue;
 
 /*
  * cvm_oct_poll_queue_stopping - flag to indicate polling should stop.
@@ -121,8 +117,7 @@ static void cvm_oct_rx_refill_worker(struct work_struct *work)
 	cvm_oct_rx_refill_pool(num_packet_buffers / 2);
 
 	if (!atomic_read(&cvm_oct_poll_queue_stopping))
-		queue_delayed_work(cvm_oct_poll_queue,
-				   &cvm_oct_rx_refill_work, HZ);
+		schedule_delayed_work(&cvm_oct_rx_refill_work, HZ);
 }
 
 static void cvm_oct_periodic_worker(struct work_struct *work)
@@ -138,8 +133,7 @@ static void cvm_oct_periodic_worker(struct work_struct *work)
 						cvm_oct_device[priv->port]);
 
 	if (!atomic_read(&cvm_oct_poll_queue_stopping))
-		queue_delayed_work(cvm_oct_poll_queue,
-						&priv->port_periodic_work, HZ);
+		schedule_delayed_work(&priv->port_periodic_work, HZ);
 }
 
 static void cvm_oct_configure_common_hw(void)
@@ -666,11 +660,6 @@ static int cvm_oct_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
-	cvm_oct_poll_queue = create_singlethread_workqueue("octeon-ethernet");
-	if (!cvm_oct_poll_queue) {
-		pr_err("octeon-ethernet: Cannot create workqueue");
-		return -ENOMEM;
-	}
 
 	cvm_oct_configure_common_hw();
 
@@ -828,8 +817,7 @@ static int cvm_oct_probe(struct platform_device *pdev)
 				fau -=
 				    cvmx_pko_get_num_queues(priv->port) *
 				    sizeof(u32);
-				queue_delayed_work(cvm_oct_poll_queue,
-						&priv->port_periodic_work, HZ);
+				schedule_delayed_work(&priv->port_periodic_work, HZ);
 			}
 		}
 	}
@@ -842,7 +830,7 @@ static int cvm_oct_probe(struct platform_device *pdev)
 	 */
 	cvm_oct_tx_poll_interval = 150 * (octeon_get_clock_rate() / 1000000);
 
-	queue_delayed_work(cvm_oct_poll_queue, &cvm_oct_rx_refill_work, HZ);
+	schedule_delayed_work(&cvm_oct_rx_refill_work, HZ);
 
 	return 0;
 }
@@ -885,7 +873,6 @@ static int cvm_oct_remove(struct platform_device *pdev)
 		}
 	}
 
-	destroy_workqueue(cvm_oct_poll_queue);
 
 	cvmx_pko_shutdown();
 

drivers/staging/octeon/octeon-ethernet.h

@@ -76,7 +76,6 @@ extern int pow_send_group;
 extern int pow_receive_group;
 extern char pow_send_list[];
 extern struct net_device *cvm_oct_device[];
-extern struct workqueue_struct *cvm_oct_poll_queue;
 extern atomic_t cvm_oct_poll_queue_stopping;
 extern u64 cvm_oct_tx_poll_interval;