1 | #ifndef _LINUX_MEMBARRIER_H |
2 | #define _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 on success. The |
56 | * "expedited" commands complete faster than |
57 | * the non-expedited ones, they never block, |
58 | * but have the downside of causing extra |
59 | * overhead. A process needs to register its |
60 | * intent to use the private expedited command |
61 | * prior to using it, otherwise this command |
62 | * returns -EPERM. |
63 | * @MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED: |
64 | * Register the process intent to use |
65 | * MEMBARRIER_CMD_PRIVATE_EXPEDITED. Always |
66 | * returns 0. |
67 | * |
68 | * Command to be passed to the membarrier system call. The commands need to |
69 | * be a single bit each, except for MEMBARRIER_CMD_QUERY which is assigned to |
70 | * the value 0. |
71 | */ |
72 | enum membarrier_cmd { |
73 | MEMBARRIER_CMD_QUERY = 0, |
74 | MEMBARRIER_CMD_SHARED = (1 << 0), |
75 | /* reserved for MEMBARRIER_CMD_SHARED_EXPEDITED (1 << 1) */ |
76 | /* reserved for MEMBARRIER_CMD_PRIVATE (1 << 2) */ |
77 | MEMBARRIER_CMD_PRIVATE_EXPEDITED = (1 << 3), |
78 | MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED = (1 << 4), |
79 | }; |
80 | |
81 | #endif /* _LINUX_MEMBARRIER_H */ |
82 | |