USB: EHCI: log a warning if ehci-hcd is not loaded first

This patch (as1139) adds a warning to the system log whenever ehci-hcd
is loaded after ohci-hcd or uhci-hcd.  Nowadays most distributions are
pretty good about not doing this; maybe the warning will help convince
anyone still doing it wrong.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@kernel.org>  [2.6.27]
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/core/hcd.c

@@ -81,6 +81,10 @@
 
 /*-------------------------------------------------------------------------*/
 
+/* Keep track of which host controller drivers are loaded */
+unsigned long usb_hcds_loaded;
+EXPORT_SYMBOL_GPL(usb_hcds_loaded);
+
 /* host controllers we manage */
 LIST_HEAD (usb_bus_list);
 EXPORT_SYMBOL_GPL (usb_bus_list);

drivers/usb/core/hcd.h

@@ -482,4 +482,10 @@ static inline void usbmon_urb_complete(struct usb_bus *bus, struct urb *urb,
  */
 extern struct rw_semaphore ehci_cf_port_reset_rwsem;
 
+/* Keep track of which host controller drivers are loaded */
+#define USB_UHCI_LOADED		0
+#define USB_OHCI_LOADED		1
+#define USB_EHCI_LOADED		2
+extern unsigned long usb_hcds_loaded;
+
 #endif /* __KERNEL__ */

drivers/usb/host/ehci-hcd.c

@@ -1046,6 +1046,12 @@ static int __init ehci_hcd_init(void)
 		return -ENODEV;
 
 	printk(KERN_INFO "%s: " DRIVER_DESC "\n", hcd_name);
+	set_bit(USB_EHCI_LOADED, &usb_hcds_loaded);
+	if (test_bit(USB_UHCI_LOADED, &usb_hcds_loaded) ||
+			test_bit(USB_OHCI_LOADED, &usb_hcds_loaded))
+		printk(KERN_WARNING "Warning! ehci_hcd should always be loaded"
+				" before uhci_hcd and ohci_hcd, not after\n");
+
 	pr_debug("%s: block sizes: qh %Zd qtd %Zd itd %Zd sitd %Zd\n",
 		 hcd_name,
 		 sizeof(struct ehci_qh), sizeof(struct ehci_qtd),
@@ -1053,8 +1059,10 @@ static int __init ehci_hcd_init(void)
 
 #ifdef DEBUG
 	ehci_debug_root = debugfs_create_dir("ehci", NULL);
-	if (!ehci_debug_root)
-		return -ENOENT;
+	if (!ehci_debug_root) {
+		retval = -ENOENT;
+		goto err_debug;
+	}
 #endif
 
 #ifdef PLATFORM_DRIVER
@@ -1102,6 +1110,8 @@ clean0:
 	debugfs_remove(ehci_debug_root);
 	ehci_debug_root = NULL;
 #endif
+err_debug:
+	clear_bit(USB_EHCI_LOADED, &usb_hcds_loaded);
 	return retval;
 }
 module_init(ehci_hcd_init);
@@ -1123,6 +1133,7 @@ static void __exit ehci_hcd_cleanup(void)
 #ifdef DEBUG
 	debugfs_remove(ehci_debug_root);
 #endif
+	clear_bit(USB_EHCI_LOADED, &usb_hcds_loaded);
 }
 module_exit(ehci_hcd_cleanup);
 

drivers/usb/host/ohci-hcd.c

@@ -1095,6 +1095,7 @@ static int __init ohci_hcd_mod_init(void)
 	printk(KERN_INFO "%s: " DRIVER_DESC "\n", hcd_name);
 	pr_debug ("%s: block sizes: ed %Zd td %Zd\n", hcd_name,
 		sizeof (struct ed), sizeof (struct td));
+	set_bit(USB_OHCI_LOADED, &usb_hcds_loaded);
 
 #ifdef DEBUG
 	ohci_debug_root = debugfs_create_dir("ohci", NULL);
@@ -1181,6 +1182,7 @@ static int __init ohci_hcd_mod_init(void)
  error_debug:
 #endif
 
+	clear_bit(USB_OHCI_LOADED, &usb_hcds_loaded);
 	return retval;
 }
 module_init(ohci_hcd_mod_init);
@@ -1211,6 +1213,7 @@ static void __exit ohci_hcd_mod_exit(void)
 #ifdef DEBUG
 	debugfs_remove(ohci_debug_root);
 #endif
+	clear_bit(USB_OHCI_LOADED, &usb_hcds_loaded);
 }
 module_exit(ohci_hcd_mod_exit);
 

drivers/usb/host/uhci-hcd.c

@@ -955,6 +955,7 @@ static int __init uhci_hcd_init(void)
 
 	printk(KERN_INFO "uhci_hcd: " DRIVER_DESC "%s\n",
 			ignore_oc ? ", overcurrent ignored" : "");
+	set_bit(USB_UHCI_LOADED, &usb_hcds_loaded);
 
 	if (DEBUG_CONFIGURED) {
 		errbuf = kmalloc(ERRBUF_LEN, GFP_KERNEL);
@@ -987,6 +988,7 @@ debug_failed:
 
 errbuf_failed:
 
+	clear_bit(USB_UHCI_LOADED, &usb_hcds_loaded);
 	return retval;
 }
 
@@ -996,6 +998,7 @@ static void __exit uhci_hcd_cleanup(void)
 	kmem_cache_destroy(uhci_up_cachep);
 	debugfs_remove(uhci_debugfs_root);
 	kfree(errbuf);
+	clear_bit(USB_UHCI_LOADED, &usb_hcds_loaded);
 }
 
 module_init(uhci_hcd_init);