wrapper/writeback.h

   1 #ifndef _LTTNG_WRAPPER_WRITEBACK_H
   2 #define _LTTNG_WRAPPER_WRITEBACK_H
   3
   4 /*
   5  * wrapper/writeback.h
   6  *
   7  * wrapper around global_dirty_limit read. Using KALLSYMS with KALLSYMS_ALL
   8  * to get its address when available, else we need to have a kernel that
   9  * exports this variable to GPL modules.
  10  *
  11  * Copyright (C) 2013 Mentor Graphics Corp.
  12  *
  13  * This library is free software; you can redistribute it and/or
  14  * modify it under the terms of the GNU Lesser General Public
  15  * License as published by the Free Software Foundation; only
  16  * version 2.1 of the License.
  17  *
  18  * This library is distributed in the hope that it will be useful,
  19  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  21  * Lesser General Public License for more details.
  22  *
  23  * You should have received a copy of the GNU Lesser General Public
  24  * License along with this library; if not, write to the Free Software
  25  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  26  */
  27
  28 #ifdef CONFIG_KALLSYMS_ALL
  29
  30 #include <linux/kallsyms.h>
  31 #include "kallsyms.h"
  32
  33 static unsigned long *global_dirty_limit_sym;
  34
  35 static inline
  36 unsigned long wrapper_global_dirty_limit(void)
  37 {
  38         if (!global_dirty_limit_sym)
  39                 global_dirty_limit_sym =
  40                         (void *) kallsyms_lookup_dataptr("global_dirty_limit");
  41         if (global_dirty_limit_sym) {
  42                 return *global_dirty_limit_sym;
  43         } else {
  44                 printk(KERN_WARNING "LTTng: global_dirty_limit symbol lookup failed.\n");
  45                 return 0;
  46         }
  47 }
  48
  49 #else
  50
  51 #include <linux/writeback.h>
  52
  53 static inline
  54 unsigned long wrapper_global_dirty_limit(void)
  55 {
  56         return global_dirty_limit;
  57 }
  58
  59 #endif
  60
  61 #endif /* _LTTNG_WRAPPER_WRITEBACK_H */