net/mlx5_core/health: Remove deprecated create_singlethread_workqueue

The workqueue health->wq was used as per device private health thread.
This was done to perform delayed work.

The workqueue has a single workitem(&health->work) and
hence doesn't require ordering. It is involved in handling the health of
the device and is not being used on a memory reclaim path.
Hence, the singlethreaded workqueue has been replaced with the use of
system_wq.

Work item has been flushed in mlx5_health_cleanup() to ensure that
there are no pending tasks while disconnecting the driver.

Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@gmail.com>
Acked-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx5/core/health.c

@@ -272,7 +272,7 @@ static void poll_health(unsigned long data)
 	if (in_fatal(dev) && !health->sick) {
 		health->sick = true;
 		print_health_info(dev);
-		queue_work(health->wq, &health->work);
+		schedule_work(&health->work);
 	}
 }
 
@@ -301,7 +301,7 @@ void mlx5_health_cleanup(struct mlx5_core_dev *dev)
 {
 	struct mlx5_core_health *health = &dev->priv.health;
 
-	destroy_workqueue(health->wq);
+	flush_work(&health->work);
 }
 
 int mlx5_health_init(struct mlx5_core_dev *dev)
@@ -316,10 +316,7 @@ int mlx5_health_init(struct mlx5_core_dev *dev)
 
 	strcpy(name, "mlx5_health");
 	strcat(name, dev_name(&dev->pdev->dev));
-	health->wq = create_singlethread_workqueue(name);
 	kfree(name);
-	if (!health->wq)
-		return -ENOMEM;
 
 	INIT_WORK(&health->work, health_care);