pegasus: minor resource shrinkage

Make pegasus driver not allocate a workqueue until the driver
is bound to some device, which will need that workqueue if
the device is brought up.  This conserves resources when the
driver is linked but there's no pegasus device connected.

Also shrink the runtime footprint a smidgeon by moving some
init-only code into its proper section, and move an obnoxious
(frequent and meaningless) message to be debug-only.
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/usb/pegasus.c

@@ -1213,7 +1213,7 @@ static void pegasus_set_multicast(struct net_device *net)
 		pegasus->eth_regs[EthCtrl0] |= RX_MULTICAST;
 		pegasus->eth_regs[EthCtrl2] &= ~RX_PROMISCUOUS;
 		if (netif_msg_link(pegasus))
-			pr_info("%s: set allmulti\n", net->name);
+			pr_debug("%s: set allmulti\n", net->name);
 	} else {
 		pegasus->eth_regs[EthCtrl0] &= ~RX_MULTICAST;
 		pegasus->eth_regs[EthCtrl2] &= ~RX_PROMISCUOUS;
@@ -1273,6 +1273,7 @@ static inline void setup_pegasus_II(pegasus_t * pegasus)
 }
 
 
+static int pegasus_count;
 static struct workqueue_struct *pegasus_workqueue = NULL;
 #define CARRIER_CHECK_DELAY (2 * HZ)
 
@@ -1301,6 +1302,18 @@ static int pegasus_blacklisted(struct usb_device *udev)
 	return 0;
 }
 
+/* we rely on probe() and remove() being serialized so we
+ * don't need extra locking on pegasus_count.
+ */
+static void pegasus_dec_workqueue(void)
+{
+	pegasus_count--;
+	if (pegasus_count == 0) {
+		destroy_workqueue(pegasus_workqueue);
+		pegasus_workqueue = NULL;
+	}
+}
+
 static int pegasus_probe(struct usb_interface *intf,
 			 const struct usb_device_id *id)
 {
@@ -1310,12 +1323,17 @@ static int pegasus_probe(struct usb_interface *intf,
 	int dev_index = id - pegasus_ids;
 	int res = -ENOMEM;
 
-	usb_get_dev(dev);
+	if (pegasus_blacklisted(dev))
+		return -ENODEV;
 
-	if (pegasus_blacklisted(dev)) {
-		res = -ENODEV;
-		goto out;
+	if (pegasus_count == 0) {
+		pegasus_workqueue = create_singlethread_workqueue("pegasus");
+		if (!pegasus_workqueue)
+			return -ENOMEM;
 	}
+	pegasus_count++;
+
+	usb_get_dev(dev);
 
 	net = alloc_etherdev(sizeof(struct pegasus));
 	if (!net) {
@@ -1400,6 +1418,7 @@ static int pegasus_probe(struct usb_interface *intf,
 	free_netdev(net);
 out:
 	usb_put_dev(dev);
+	pegasus_dec_workqueue();
 	return res;
 }
 
@@ -1425,6 +1444,7 @@ static void pegasus_disconnect(struct usb_interface *intf)
 		pegasus->rx_skb = NULL;
 	}
 	free_netdev(pegasus->net);
+	pegasus_dec_workqueue();
 }
 
 static int pegasus_suspend (struct usb_interface *intf, pm_message_t message)
@@ -1468,7 +1488,7 @@ static struct usb_driver pegasus_driver = {
 	.resume = pegasus_resume,
 };
 
-static void parse_id(char *id)
+static void __init parse_id(char *id)
 {
 	unsigned int vendor_id=0, device_id=0, flags=0, i=0;
 	char *token, *name=NULL;
@@ -1504,15 +1524,11 @@ static int __init pegasus_init(void)
 	pr_info("%s: %s, " DRIVER_DESC "\n", driver_name, DRIVER_VERSION);
 	if (devid)
 		parse_id(devid);
-	pegasus_workqueue = create_singlethread_workqueue("pegasus");
-	if (!pegasus_workqueue)
-		return -ENOMEM;
 	return usb_register(&pegasus_driver);
 }
 
 static void __exit pegasus_exit(void)
 {
-	destroy_workqueue(pegasus_workqueue);
 	usb_deregister(&pegasus_driver);
 }