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>

5 files changed, 29 insertions, 2 deletions

diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index c8035a8216bd..fc9018e72a09 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 e710ce04e228..2dcde61c465e 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 fcbc1f2b2377..358df2a6c396 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/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);
 
diff --git a/drivers/usb/host/ohci-hcd.c b/drivers/usb/host/ohci-hcd.c
index 0afeda836df3..8647dab0d7f9 100644
--- a/drivers/usb/host/ohci-hcd.c
+++ b/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);
 
diff --git a/drivers/usb/host/uhci-hcd.c b/drivers/usb/host/uhci-hcd.c
index 2dddb258b0db..cf5e4cf7ea42 100644
--- a/drivers/usb/host/uhci-hcd.c
+++ b/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);