io_uring_prep_futex_wait(3) — Linux manual page


io_uring_prep_futex_wait(3)  liburing Manual io_uring_prep_futex_wait(3)

NAME         top

       io_uring_prep_futex_wait - prepare a futex wait request

SYNOPSIS         top

       #include <linux/futex.h>
       #include <unistd.h>
       #include <liburing.h>

       void io_uring_prep_futex_wait(struct io_uring_sqe *sqe,
                                     uint32_t *futex,
                                     uint64_t val,
                                     uint64_t mask,
                                     uint32_t futex_flags,
                                     unsigned int flags);

DESCRIPTION         top

       The io_uring_prep_futex_wait(3) function prepares a futex wait
       request. The submission queue entry sqe is setup for waiting on a
       futex at address futex and which still has the value val and with
       futex2(2) flags of futex_flags and io_uring futex flags of flags

       mask can be set to a specific bitset mask, which will be matched
       by the waking side to decide who to wake up. To always get woken,
       an application may use FUTEX_BITSET_MATCH_ANY .

       futex_flags follows the futex2(2) flags, not the futex(2) v1
       interface flags.

       flags are currently unused and hence 0 must be passed.

       This function prepares an async futex(2) wait request. See that
       man page for details. Note that the io_uring futex wait request
       is similar to the FUTEX_WAIT_BITSET operation, as FUTEX_WAIT is a
       strict subset of that.

RETURN VALUE         top


ERRORS         top

       The CQE res field will contain the result of the operation. See
       the related man page for details on possible values. Note that
       where synchronous system calls will return -1 on failure and set
       errno to the actual error value, io_uring never uses errno.
       Instead it returns the negated errno directly in the CQE res

NOTES         top

       Unlike the sync futex syscalls that wait on a futex, io_uring
       does not support passing in a timeout for the request. Instead,
       applications are encouraged to use a linked timeout to abort the
       futex request at a given time, if desired.

SEE ALSO         top

       io_uring_get_sqe(3), io_uring_submit(3),
       io_uring_prep_futex_waitv(3), io_uring_prep_futex_wake(3),
       io_uring_prep_link_timeout(3), futex(2) futex2(2)

COLOPHON         top

       This page is part of the liburing (A library for io_uring)
       project.  Information about the project can be found at 
       ⟨⟩.  If you have a bug report for
       this manual page, send it to  This page
       was obtained from the project's upstream Git repository
       ⟨⟩ on 2023-12-22.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2023-12-19.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to

liburing-2.5                  Sep 29, 2023   io_uring_prep_futex_wait(3)

Pages that refer to this page: io_uring_prep_futex_wait(3)io_uring_prep_futex_waitv(3)io_uring_prep_futex_wake(3)