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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | STANDARDS | HISTORY | SEE ALSO | COLOPHON |
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FUTEX_WAKE(2const) FUTEX_WAKE(2const)
FUTEX_WAKE - wake waiters that are inside FUTEX_WAIT
Standard C library (libc, -lc)
#include <linux/futex.h> /* Definition of FUTEX_* constants */
#include <sys/syscall.h> /* Definition of SYS_* constants */
#include <unistd.h>
long syscall(SYS_futex, uint32_t *uaddr, FUTEX_WAKE, uint32_t val);
This operation wakes at most val of the waiters that are waiting
(e.g., inside FUTEX_WAIT(2const)) on the futex word at the address
uaddr.
Most commonly, val is specified as either 1 (wake up a single
waiter) or INT_MAX (wake up all waiters).
No guarantee is provided about which waiters are awoken (e.g., a
waiter with a higher scheduling priority is not guaranteed to be
awoken in preference to a waiter with a lower priority).
On error, -1 is returned, and errno is set to indicate the error.
On success, FUTEX_WAKE returns the number of waiters that were
woken up.
See futex(2).
EINVAL The kernel detected an inconsistency between the user-space
state at uaddr and the kernel state—that is, it detected a
waiter which waits in FUTEX_LOCK_PI(2const) or
FUTEX_LOCK_PI2(2const) on uaddr.
Linux.
Linux 2.6.0.
futex(2)
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Linux man-pages 6.15 2025-05-30 FUTEX_WAKE(2const)
Pages that refer to this page: futex(2), FUTEX_CMP_REQUEUE(2const), FUTEX_FD(2const), FUTEX_WAIT(2const), FUTEX_WAIT_BITSET(2const), FUTEX_WAIT_REQUEUE_PI(2const)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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