include/uapi/linux/membarrier.h

   1 #ifndef _UAPI_LINUX_MEMBARRIER_H
   2 #define _UAPI_LINUX_MEMBARRIER_H
   3
   4 /*
   5  * linux/membarrier.h
   6  *
   7  * membarrier system call API
   8  *
   9  * Copyright (c) 2010, 2015 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  10  *
  11  * Permission is hereby granted, free of charge, to any person obtaining a copy
  12  * of this software and associated documentation files (the "Software"), to deal
  13  * in the Software without restriction, including without limitation the rights
  14  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  15  * copies of the Software, and to permit persons to whom the Software is
  16  * furnished to do so, subject to the following conditions:
  17  *
  18  * The above copyright notice and this permission notice shall be included in
  19  * all copies or substantial portions of the Software.
  20  *
  21  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  22  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  23  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  24  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  25  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  26  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  27  * SOFTWARE.
  28  */
  29
  30 /**
  31  * enum membarrier_cmd - membarrier system call command
  32  * @MEMBARRIER_CMD_QUERY:   Query the set of supported commands. It returns
  33  *                          a bitmask of valid commands.
  34  * @MEMBARRIER_CMD_SHARED:  Execute a memory barrier on all running threads.
  35  *                          Upon return from system call, the caller thread
  36  *                          is ensured that all running threads have passed
  37  *                          through a state where all memory accesses to
  38  *                          user-space addresses match program order between
  39  *                          entry to and return from the system call
  40  *                          (non-running threads are de facto in such a
  41  *                          state). This covers threads from all processes
  42  *                          running on the system. This command returns 0.
  43  *
  44  * Command to be passed to the membarrier system call. The commands need to
  45  * be a single bit each, except for MEMBARRIER_CMD_QUERY which is assigned to
  46  * the value 0.
  47  */
  48 enum membarrier_cmd {
  49         MEMBARRIER_CMD_QUERY = 0,
  50         MEMBARRIER_CMD_SHARED = (1 << 0),
  51 };
  52
  53 #endif /* _UAPI_LINUX_MEMBARRIER_H */