+#ifndef _LTTNG_WRAPPER_WRITEBACK_H
+#define _LTTNG_WRAPPER_WRITEBACK_H
+
+/*
+ * wrapper/writeback.h
+ *
+ * wrapper around global_dirty_limit read. Using KALLSYMS with KALLSYMS_ALL
+ * to get its address when available, else we need to have a kernel that
+ * exports this variable to GPL modules.
+ *
+ * Copyright (C) 2013 Mentor Graphics Corp.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; only
+ * version 2.1 of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifdef CONFIG_KALLSYMS_ALL
+
+#include <linux/kallsyms.h>
+#include "kallsyms.h"
+
+static unsigned long *global_dirty_limit_sym;
+
+static inline
+unsigned long wrapper_global_dirty_limit(void)
+{
+ if (!global_dirty_limit_sym)
+ global_dirty_limit_sym =
+ (void *) kallsyms_lookup_dataptr("global_dirty_limit");
+ if (global_dirty_limit_sym) {
+ return *global_dirty_limit_sym;
+ } else {
+ printk(KERN_WARNING "LTTng: global_dirty_limit symbol lookup failed.\n");
+ return 0;
+ }
+}
+
+#else
+
+#include <linux/writeback.h>
+
+static inline
+unsigned long wrapper_global_dirty_limit(void)
+{
+ return global_dirty_limit;
+}
+
+#endif
+
+#endif /* _LTTNG_WRAPPER_WRITEBACK_H */