[PATCH] Driver core: link device and all class devices derived from it.

Driver core: link device and all class devices derived from it.

To ease the task of locating class devices derived from a certain
device create symlinks from parent device to its class devices.
Change USB host class device name from usbX to usb_hostX to avoid
conflict when creating aforementioned links.

Tweaked by Greg to have the symlink be "class_name:class_device_name" in
order to prevent duplicate links.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 32 insertions, 3 deletions

diff --git a/drivers/base/class.c b/drivers/base/class.c
index 0154a1623b21..d207296b18dc 100644
--- a/drivers/base/class.c
+++ b/drivers/base/class.c
@@ -452,10 +452,29 @@ void class_device_initialize(struct class_device *class_dev)
         INIT_LIST_HEAD(&class_dev->node);
 }
 
+static char *make_class_name(struct class_device *class_dev)
+{
+        char *name;
+        int size;
+
+        size = strlen(class_dev->class->name) +
+                strlen(kobject_name(&class_dev->kobj)) + 2;
+
+        name = kmalloc(size, GFP_KERNEL);
+        if (!name)
+                return ERR_PTR(-ENOMEM);
+
+        strcpy(name, class_dev->class->name);
+        strcat(name, ":");
+        strcat(name, kobject_name(&class_dev->kobj));
+        return name;
+}
+
 int class_device_add(struct class_device *class_dev)
 {
         struct class * parent = NULL;
         struct class_interface * class_intf;
+        char *class_name = NULL;
         int error;
 
         class_dev = class_device_get(class_dev);
@@ -500,9 +519,13 @@ int class_device_add(struct class_device *class_dev)
         }
 
         class_device_add_attrs(class_dev);
-        if (class_dev->dev)
+        if (class_dev->dev) {
+                class_name = make_class_name(class_dev);
                 sysfs_create_link(&class_dev->kobj,
                                   &class_dev->dev->kobj, "device");
+                sysfs_create_link(&class_dev->dev->kobj, &class_dev->kobj,
+                                  class_name);
+        }
 
         /* notify any interfaces this device is now here */
         if (parent) {
@@ -519,6 +542,7 @@ int class_device_add(struct class_device *class_dev)
         if (error && parent)
                 class_put(parent);
         class_device_put(class_dev);
+        kfree(class_name);
         return error;
 }
 
@@ -584,6 +608,7 @@ void class_device_del(struct class_device *class_dev)
 {
         struct class * parent = class_dev->class;
         struct class_interface * class_intf;
+        char *class_name = NULL;
 
         if (parent) {
                 down(&parent->sem);
@@ -594,8 +619,11 @@ void class_device_del(struct class_device *class_dev)
                 up(&parent->sem);
         }
 
-        if (class_dev->dev)
+        if (class_dev->dev) {
+                class_name = make_class_name(class_dev);
                 sysfs_remove_link(&class_dev->kobj, "device");
+                sysfs_remove_link(&class_dev->dev->kobj, class_name);
+        }
         if (class_dev->devt_attr)
                 class_device_remove_file(class_dev, class_dev->devt_attr);
         class_device_remove_attrs(class_dev);
@@ -605,6 +633,7 @@ void class_device_del(struct class_device *class_dev)
 
         if (parent)
                 class_put(parent);
+        kfree(class_name);
 }
 
 void class_device_unregister(struct class_device *class_dev)
diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index 79422a3b07bc..9f44e83c6a69 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -782,7 +782,7 @@ static int usb_register_bus(struct usb_bus *bus)
                 return -E2BIG;
         }
 
-        bus->class_dev = class_device_create(usb_host_class, MKDEV(0,0), bus->controller, "usb%d", busnum);
+        bus->class_dev = class_device_create(usb_host_class, MKDEV(0,0), bus->controller, "usb_host%d", busnum);
         if (IS_ERR(bus->class_dev)) {
                 clear_bit(busnum, busmap.busmap);
                 up(&usb_bus_list_lock);