Replaced the locking strategy (formerly a recursive lock for the depot and

one for each per CPU store):
* The depot is now protected by a R/W lock combined with a spinlock. It is
  required to either hold read lock + spinlock or just the write lock.
* When accessing the per CPU stores we only need to acquire the read lock
  and disable interrupts. When switching magazines with the depot we
  additionally get the spinlock.
* When allocating a new magazine we do completely unlock.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35200 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/kernel/slab/ObjectDepot.h

@@ -13,7 +13,8 @@
 struct DepotMagazine;
 
 typedef struct object_depot {
-	recursive_lock			lock;
+	rw_lock					outer_lock;
+	spinlock				inner_lock;
 	DepotMagazine*			full;
 	DepotMagazine*			empty;
 	size_t					full_count;