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

commit 9beeee6584b9aa4f9192055512411484a2a624df upstream

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

5 files changed, 29 insertions, 2 deletions

diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index 8ab389dca2b..706f3e6a07d 100644
--- a/drivers/usb/core/hcd.c
+++ b/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);
diff --git a/drivers/usb/core/hcd.h b/drivers/usb/core/hcd.h
index e710ce04e22..2dcde61c465 100644
--- a/drivers/usb/core/hcd.h
+++ b/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__ */
diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index 8409e0705d6..86e38b0569f 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -1049,6 +1049,12 @@ static int __init ehci_hcd_init(void)
 {
 	int retval = 0;
 
+	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),
@@ -1056,8 +1062,10 @@ 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
@@ -1104,7 +1112,9 @@ clean0:
 #ifdef DEBUG
 	debugfs_remove(ehci_debug_root);
 	ehci_debug_root = NULL;
+err_debug:
 #endif
+	clear_bit(USB_EHCI_LOADED, &usb_hcds_loaded);
 	return retval;
 }
 module_init(ehci_hcd_init);
@@ -1126,6 +1136,7 @@ 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);
 
diff --git a/drivers/usb/host/ohci-hcd.c b/drivers/usb/host/ohci-hcd.c
index 89901962cbf..8bec02c6736 100644
--- a/drivers/usb/host/ohci-hcd.c
+++ b/drivers/usb/host/ohci-hcd.c
@@ -1098,6 +1098,7 @@ static int __init ohci_hcd_mod_init(void)
 	printk (KERN_DEBUG "%s: " DRIVER_INFO "\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);
@@ -1184,6 +1185,7 @@ 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);
@@ -1214,6 +1216,7 @@ 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);
 
diff --git a/drivers/usb/host/uhci-hcd.c b/drivers/usb/host/uhci-hcd.c
index 3a7bfe7a887..59bed3c4259 100644
--- a/drivers/usb/host/uhci-hcd.c
+++ b/drivers/usb/host/uhci-hcd.c
@@ -953,6 +953,7 @@ static int __init uhci_hcd_init(void)
 
 	printk(KERN_INFO DRIVER_DESC " " DRIVER_VERSION "%s\n",
 			ignore_oc ? ", overcurrent ignored" : "");
+	set_bit(USB_UHCI_LOADED, &usb_hcds_loaded);
 
 	if (usb_disabled())
 		return -ENODEV;
@@ -988,6 +989,7 @@ debug_failed:
 
 errbuf_failed:
 
+	clear_bit(USB_UHCI_LOADED, &usb_hcds_loaded);
 	return retval;
 }
 
@@ -997,6 +999,7 @@ 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);