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 */ 90