driver core: fix namespace issue with devices assigned to classes

  - uses a kset in "struct class" to keep track of all directories
    belonging to this class
  - merges with the /sys/devices/virtual logic.
  - removes the namespace-dir if the last member of that class
    leaves the directory.

There may be locking or refcounting fixes left, I stopped when it seemed
to work with network and sound modules. :)

From: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 10 insertions, 6 deletions

diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c
index 82fc1794b691..4122f38330d4 100644
--- a/lib/kobject_uevent.c
+++ b/lib/kobject_uevent.c
@@ -115,6 +115,16 @@ int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
                         return 0;
                 }
 
+        /* originating subsystem */
+        if (uevent_ops && uevent_ops->name)
+                subsystem = uevent_ops->name(kset, kobj);
+        else
+                subsystem = kobject_name(&kset->kobj);
+        if (!subsystem) {
+                pr_debug("unset subsytem caused the event to drop!\n");
+                return 0;
+        }
+
         /* environment index */
         envp = kzalloc(NUM_ENVP * sizeof (char *), GFP_KERNEL);
         if (!envp)
@@ -134,12 +144,6 @@ int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
                 goto exit;
         }
 
-        /* originating subsystem */
-        if (uevent_ops && uevent_ops->name)
-                subsystem = uevent_ops->name(kset, kobj);
-        else
-                subsystem = kobject_name(&kset->kobj);
-
         /* event environemnt for helper process only */
         envp[i++] = "HOME=/";
         envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";