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 #include <lttng-kernel-version.h>
  29
  30 #ifdef CONFIG_KALLSYMS_ALL
  31 #include <linux/kallsyms.h>
  32 #include <wrapper/kallsyms.h>
  33
  34
  35
  36 #if LINUX_VERSION_CODE >= KERNEL_VERSION(4,2,0)
  37
  38 static struct wb_domain *global_wb_domain_sym;
  39
  40 static inline
  41 unsigned long wrapper_global_dirty_limit(void)
  42 {
  43         if (!global_wb_domain_sym)
  44                 global_wb_domain_sym =
  45                         (void *) kallsyms_lookup_dataptr("global_wb_domain");
  46         if (global_wb_domain_sym) {
  47                 return global_wb_domain_sym->dirty_limit;
  48         } else {
  49                 printk_once(KERN_WARNING "LTTng: global_wb_domain symbol lookup failed.\n");
  50                 return 0;
  51         }
  52 }
  53 #else
  54
  55 static unsigned long *global_dirty_limit_sym;
  56
  57 static inline
  58 unsigned long wrapper_global_dirty_limit(void)
  59 {
  60         if (!global_dirty_limit_sym)
  61                 global_dirty_limit_sym =
  62                         (void *) kallsyms_lookup_dataptr("global_dirty_limit");
  63         if (global_dirty_limit_sym) {
  64                 return *global_dirty_limit_sym;
  65         } else {
  66                 printk_once(KERN_WARNING "LTTng: global_dirty_limit symbol lookup failed.\n");
  67                 return 0;
  68         }
  69 }
  70 #endif
  71
  72 #else /* CONFIG_KALLSYMS_ALL */
  73
  74 #include <linux/writeback.h>
  75
  76 static inline
  77 unsigned long wrapper_global_dirty_limit(void)
  78 {
  79         return global_dirty_limit;
  80 }
  81
  82 #endif
  83
  84 #endif /* _LTTNG_WRAPPER_WRITEBACK_H */