class: change internal semaphore to a mutex

Now that the lockdep infrastructure in the class core is in place, we
should be able to properly change the internal class semaphore to be a
mutex.

David wrote the original patch, and Greg fixed it up to apply properly
due to all of the recent changes in this area.

From: Dave Young <hidave.darkstar@gmail.com>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 5 insertions, 4 deletions

diff --git a/drivers/base/core.c b/drivers/base/core.c
index b90ae6f7be86..c05b1159023e 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -21,6 +21,7 @@
 #include <linux/genhd.h>
 #include <linux/kallsyms.h>
 #include <linux/semaphore.h>
+#include <linux/mutex.h>
 
 #include "base.h"
 #include "power/power.h"
@@ -907,7 +908,7 @@ int device_add(struct device *dev)
                 klist_add_tail(&dev->knode_parent, &parent->klist_children);
 
         if (dev->class) {
-                down(&dev->class->p->class_sem);
+                mutex_lock(&dev->class->p->class_mutex);
                 /* tie the class to the device */
                 list_add_tail(&dev->node, &dev->class->p->class_devices);
 
@@ -916,7 +917,7 @@ int device_add(struct device *dev)
                                     &dev->class->p->class_interfaces, node)
                         if (class_intf->add_dev)
                                 class_intf->add_dev(dev, class_intf);
-                up(&dev->class->p->class_sem);
+                mutex_unlock(&dev->class->p->class_mutex);
         }
  Done:
         put_device(dev);
@@ -1017,7 +1018,7 @@ void device_del(struct device *dev)
         if (dev->class) {
                 device_remove_class_symlinks(dev);
 
-                down(&dev->class->p->class_sem);
+                mutex_lock(&dev->class->p->class_mutex);
                 /* notify any interfaces that the device is now gone */
                 list_for_each_entry(class_intf,
                                     &dev->class->p->class_interfaces, node)
@@ -1025,7 +1026,7 @@ void device_del(struct device *dev)
                                 class_intf->remove_dev(dev, class_intf);
                 /* remove the device from the class list */
                 list_del_init(&dev->node);
-                up(&dev->class->p->class_sem);
+                mutex_unlock(&dev->class->p->class_mutex);
         }
         device_remove_file(dev, &uevent_attr);
         device_remove_attrs(dev);