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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | NOTES | SEE ALSO | COLOPHON |
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io_uring_prep_futex_wait(3) liburing Manual io_uring_prep_futex_wait(3)
io_uring_prep_futex_wait - prepare a futex wait request
#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);
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.
None
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
field.
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.
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)
This page is part of the liburing (A library for io_uring)
project. Information about the project can be found at
⟨https://github.com/axboe/liburing⟩. If you have a bug report for
this manual page, send it to io-uring@vger.kernel.org. This page
was obtained from the project's upstream Git repository
⟨https://github.com/axboe/liburing⟩ 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
man-pages@man7.org
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)
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HTML rendering created 2023-12-22 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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