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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | NOTES | SEE ALSO | COLOPHON |
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io_uring_prep_timeout(3) liburing Manual io_uring_prep_timeout(3)
io_uring_prep_timeout - prepare a timeout request
#include <liburing.h>
void io_uring_prep_timeout(struct io_uring_sqe *sqe,
struct __kernel_timespec *ts,
unsigned count,
unsigned flags);
The io_uring_prep_timeout(3) function prepares a timeout request.
The submission queue entry sqe is setup to arm a timeout specified
by ts and with a timeout count of count completion entries. The
flags argument holds modifier flags for the request.
This request type can be used as a timeout waking anyone sleeping
for events on the CQ ring. The flags argument may contain:
IORING_TIMEOUT_ABS
The value specified in ts is an absolute value rather than
a relative one.
IORING_TIMEOUT_BOOTTIME
The boottime clock source should be used.
IORING_TIMEOUT_REALTIME
The realtime clock source should be used.
IORING_TIMEOUT_ETIME_SUCCESS
Consider an expired timeout a success in terms of the
posted completion. This means it will not sever dependent
links, as a failed request normally would. The posted CQE
result code will still contain -ETIME in the res value.
IORING_TIMEOUT_MULTISHOT
The request will return multiple timeout completions. The
completion flag IORING_CQE_F_MORE is set if more timeouts
are expected. The value specified in count is the number of
repeats. A value of 0 means the timeout is indefinite and
can only be stopped by a removal request. Available since
the 6.4 kernel.
If no alternate clock source is given in the above flags, then
CLOCK_MONOTONIC is used.
The timeout completion event will trigger if either the specified
timeout has occurred, or the specified number of events to wait
for have been posted to the CQ ring.
None
These are the errors that are reported in the CQE res field. On
success, 0 is returned.
-ETIME The specified timeout occurred and triggered the completion
event.
-EINVAL
One of the fields set in the SQE was invalid. For example,
two clocksources were given, or the specified timeout
seconds or nanoseconds were < 0.
-EFAULT
io_uring was unable to access the data specified by ts.
-ECANCELED
The timeout was canceled by a removal request.
As with any request that passes in data in a struct, that data
must remain valid until the request has been successfully
submitted. It need not remain valid until completion. Once a
request has been submitted, the in-kernel state is stable. Very
early kernels (5.4 and earlier) required state to be stable until
the completion occurred. Applications can test for this behavior
by inspecting the IORING_FEAT_SUBMIT_STABLE flag passed back from
io_uring_queue_init_params(3).
io_uring_get_sqe(3), io_uring_submit(3),
io_uring_prep_timeout_remove(3), io_uring_prep_timeout_update(3)
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 2025-08-11. (At that time,
the date of the most recent commit that was found in the
repository was 2025-08-02.) 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-2.2 March 12, 2022 io_uring_prep_timeout(3)
Pages that refer to this page: io_uring_prep_link_timeout(3), io_uring_prep_timeout(3), io_uring_prep_timeout_remove(3), io_uring_prep_timeout_update(3)
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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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