1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * Glibc independent futex library for testing kernel functionality.
4 * Shamelessly stolen from Darren Hart <dvhltc@us.ibm.com>
5 * http://git.kernel.org/cgit/linux/kernel/git/dvhart/futextest.git/
6 */
7
8 #ifndef _FUTEX_H
9 #define _FUTEX_H
10
11 #include <unistd.h>
12 #include <sys/syscall.h>
13 #include <sys/types.h>
14 #include <linux/futex.h>
15
16 /**
17 * futex() - SYS_futex syscall wrapper
18 * @uaddr: address of first futex
19 * @op: futex op code
20 * @val: typically expected value of uaddr, but varies by op
21 * @timeout: typically an absolute struct timespec (except where noted
22 * otherwise). Overloaded by some ops
23 * @uaddr2: address of second futex for some ops\
24 * @val3: varies by op
25 * @opflags: flags to be bitwise OR'd with op, such as FUTEX_PRIVATE_FLAG
26 *
27 * futex() is used by all the following futex op wrappers. It can also be
28 * used for misuse and abuse testing. Generally, the specific op wrappers
29 * should be used instead. It is a macro instead of an static inline function as
30 * some of the types over overloaded (timeout is used for nr_requeue for
31 * example).
32 *
33 * These argument descriptions are the defaults for all
34 * like-named arguments in the following wrappers except where noted below.
35 */
36 #define futex(uaddr, op, val, timeout, uaddr2, val3, opflags) \
37 syscall(SYS_futex, uaddr, op | opflags, val, timeout, uaddr2, val3)
38
39 /**
40 * futex_wait() - block on uaddr with optional timeout
41 * @timeout: relative timeout
42 */
43 static inline int
44 futex_wait(u_int32_t *uaddr, u_int32_t val, struct timespec *timeout, int opflags)
45 {
46 return futex(uaddr, FUTEX_WAIT, val, timeout, NULL, 0, opflags);
47 }
48
49 /**
50 * futex_wake() - wake one or more tasks blocked on uaddr
51 * @nr_wake: wake up to this many tasks
52 */
53 static inline int
54 futex_wake(u_int32_t *uaddr, int nr_wake, int opflags)
55 {
56 return futex(uaddr, FUTEX_WAKE, nr_wake, NULL, NULL, 0, opflags);
57 }
58
59 /**
60 * futex_lock_pi() - block on uaddr as a PI mutex
61 */
62 static inline int
63 futex_lock_pi(u_int32_t *uaddr, struct timespec *timeout, int opflags)
64 {
65 return futex(uaddr, FUTEX_LOCK_PI, 0, timeout, NULL, 0, opflags);
66 }
67
68 /**
69 * futex_unlock_pi() - release uaddr as a PI mutex, waking the top waiter
70 */
71 static inline int
72 futex_unlock_pi(u_int32_t *uaddr, int opflags)
73 {
74 return futex(uaddr, FUTEX_UNLOCK_PI, 0, NULL, NULL, 0, opflags);
75 }
76
77 /**
78 * futex_cmp_requeue() - requeue tasks from uaddr to uaddr2
79 * @nr_wake: wake up to this many tasks
80 * @nr_requeue: requeue up to this many tasks
81 */
82 static inline int
83 futex_cmp_requeue(u_int32_t *uaddr, u_int32_t val, u_int32_t *uaddr2, int nr_wake,
84 int nr_requeue, int opflags)
85 {
86 return futex(uaddr, FUTEX_CMP_REQUEUE, nr_wake, nr_requeue, uaddr2,
87 val, opflags);
88 }
89 #endif /* _FUTEX_H */