Move pagemgr to generic lock free structure.

2 files changed, 50 insertions, 2 deletions

diff --git a/src/include/kernel/pagemgr.H b/src/include/kernel/pagemgr.H
index 1d7193b22..b99cedff2 100644
--- a/src/include/kernel/pagemgr.H
+++ b/src/include/kernel/pagemgr.H
@@ -2,6 +2,7 @@
 #define __KERNEL_PAGEMGR_H
 
 #include <stdint.h>
+#include <util/lockfree/stack.H>
 
 /** @class PageManager
  *  @brief Manages the allocation of memory pages.
@@ -31,9 +32,9 @@ class PageManager
 	
 	struct page_t
 	{
-	    page_t* next_page;
+	    page_t* next;
 	};
-	page_t* first_page[BUCKETS];
+	Util::Lockfree::Stack<page_t> first_page[BUCKETS];
 
 	page_t* pop_bucket(size_t);
 	void push_bucket(page_t*, size_t);
diff --git a/src/include/util/lockfree/stack.H b/src/include/util/lockfree/stack.H
new file mode 100644
index 000000000..8f884e072
--- /dev/null
+++ b/src/include/util/lockfree/stack.H
@@ -0,0 +1,47 @@
+#ifndef __UTIL_LOCKFREE_STACK_H
+#define __UTIL_LOCKFREE_STACK_H
+
+#include <stddef.h>
+
+namespace Util
+{
+    namespace Lockfree
+    {
+	template <typename _T>
+	class Stack
+	{
+	    public:
+		Stack() : head(NULL) {};
+		
+		_T* pop();
+		void push(_T*);
+
+	    private:
+		_T* head;
+	};
+
+	template <typename _T>
+	_T* Stack<_T>::pop()
+	{
+	    _T * h = head;
+	    if (NULL == h) return h;
+	    if (!__sync_bool_compare_and_swap(&head,
+					      h,
+					      h->next))
+		return pop();
+	    return h;
+	}
+
+	template <typename _T>
+	void Stack<_T>::push(_T* p)
+	{
+	    p->next = head;
+	    if (!__sync_bool_compare_and_swap(&head,
+					      p->next,
+					      p))
+		push(p);
+	}
+    }
+}
+
+#endif