io_uring_prep_timeout(3) — Linux manual page


io_uring_pr...oll_timeout(3) liburing Manualio_uring_pr...oll_timeout(3)

NAME         top

       io_uring_prep_timeoute - prepare a timeout request

SYNOPSIS         top

       #include <liburing.h>

       void io_uring_prep_timeout(struct io_uring_sqe *sqe,
                                  struct __kernel_timespec *ts,
                                  unsigned count,
                                  unsigned flags);

DESCRIPTION         top

       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:

              The value specified in ts is an absolute value rather than
              a relative one.

              The boottime clock source should be used.

              The realtime clock source should be used.

              Consider an expired timeout a success in terms of the
              posted completion.  Normally a timeout that triggers would
              return in a -ETIME CQE res value.

              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.

       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.

RETURN VALUE         top


ERRORS         top

       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.

              One of the fields set in the SQE was invalid. For example,
              two clocksources where given, or the specified timeout
              seconds or nanoseconds where < 0.

              io_uring was unable to access the data specified by ts.

              The timeout was canceled by a removal request.

NOTES         top

       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

SEE ALSO         top

       io_uring_get_sqe(3), io_uring_submit(3),
       io_uring_prep_timeout_remove(3), io_uring_prep_timeout_update(3)

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
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       (which is not part of the original manual page), send a mail to

liburing-2.2                 March 12, 2022 io_uring_pr...oll_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)