wrapper/kref.h

   1 #ifndef _LTTNG_WRAPPER_KREF_H
   2 #define _LTTNG_WRAPPER_KREF_H
   3
   4 /*
   5  * wrapper/kref.h
   6  *
   7  * wrapper around linux/kref.h.
   8  *
   9  * Copyright (C) 2016 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; only version 2 of the License.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License along
  21  * with this program; if not, write to the Free Software Foundation, Inc.,
  22  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  23  *
  24  * This wrapper code is derived from Linux 3.19.2 include/linux/list.h
  25  * and include/linux/rculist.h, hence the GPLv2 license applied to this
  26  * file.
  27  */
  28
  29 #include <linux/kref.h>
  30 #include <linux/rculist.h>
  31
  32 /*
  33  * lttng_kref_get: get reference count, checking for overflow.
  34  *
  35  * Return 1 if reference is taken, 0 otherwise (overflow).
  36  */
  37 static inline int lttng_kref_get(struct kref *kref)
  38 {
  39         if (atomic_add_unless(&kref->refcount, 1, INT_MAX) != INT_MAX) {
  40                 return 1;
  41         } else {
  42                 return 0;
  43         }
  44 }
  45
  46 #endif /* _LTTNG_WRAPPER_KREF_H */