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 #include <linux/version.h>
  32
  33 /*
  34  * lttng_kref_get: get reference count, checking for overflow.
  35  *
  36  * Return 1 if reference is taken, 0 otherwise (overflow).
  37  */
  38 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,11,0))
  39 static inline int lttng_kref_get(struct kref *kref)
  40 {
  41         kref_get(kref);
  42         return 1;
  43 }
  44 #else /* #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,11,0)) */
  45 static inline int lttng_kref_get(struct kref *kref)
  46 {
  47         return atomic_add_unless(&kref->refcount, 1, INT_MAX);
  48 }
  49 #endif /* #else #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,11,0)) */
  50
  51 #endif /* _LTTNG_WRAPPER_KREF_H */