io_uring_prep_futex_wake(3)     liburing Manual    io_uring_prep_futex_wake(3)

NAME
       io_uring_prep_futex_wake - prepare a futex wake request

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

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

DESCRIPTION
       The io_uring_prep_futex_wake(3) function prepares a futex wake request.
       The submission queue entry sqe is setup for waking any waiters on the
       futex indicated by futex and at most val futexes.  futex_flags
       indicates the futex2(2) modifier flags, and io_uring futex flags of
       flags .

       If a given bitset for who to wake is desired, then that must be set in
       mask .  Use FUTEX_BITSET_MATCH_ANY to match any waiter on the given
       futex.

       flags are currently unused and hence 0 must be passed.

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

       Available since kernel 6.7.


RETURN VALUE
       None

ERRORS
       The CQE res field will contain the result of the operation. On success,
       the value will be the index into futexv which received a wakeup. See
       the related man page for details on possible values for errors. 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.

SEE ALSO
       io_uring_get_sqe(3), io_uring_submit(3), io_uring_prep_futex_wait(3),
       io_uring_prep_futex_waitv(3), futex(2) futex2(2)

liburing-2.5                  September 29, 2023   io_uring_prep_futex_wake(3)