tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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 * @MEMBARRIER_CMD_PRIVATE_EXPEDITED:
44 * Execute a memory barrier on each running
45 * thread belonging to the same process as the current
46 * thread. Upon return from system call, the
47 * caller thread is ensured that all its running
48 * threads siblings have passed through a state
49 * where all memory accesses to user-space
50 * addresses match program order between entry
51 * to and return from the system call
52 * (non-running threads are de facto in such a
53 * state). This only covers threads from the
54 * same processes as the caller thread. This
55 * command returns 0. The "expedited" commands
56 * complete faster than the non-expedited ones,
57 * they never block, but have the downside of
58 * causing extra overhead.
59 *
60 * Command to be passed to the membarrier system call. The commands need to
61 * be a single bit each, except for MEMBARRIER_CMD_QUERY which is assigned to
62 * the value 0.
63 */
64enum membarrier_cmd {
65 MEMBARRIER_CMD_QUERY = 0,
66 MEMBARRIER_CMD_SHARED = (1 << 0),
67 /* reserved for MEMBARRIER_CMD_SHARED_EXPEDITED (1 << 1) */
68 /* reserved for MEMBARRIER_CMD_PRIVATE (1 << 2) */
69 MEMBARRIER_CMD_PRIVATE_EXPEDITED = (1 << 3),
70};
71
72#endif /* _UAPI_LINUX_MEMBARRIER_H */