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.TH FUTEX_REQUEUE 2const 2025-05-30 "Linux man-pages 6.15"
.SH NAME
FUTEX_REQUEUE \- wake some waiters, and requeue others
.SH LIBRARY
Standard C library
.RI ( libc ,\~ \-lc )
.SH SYNOPSIS
.nf
.BR "#include <linux/futex.h>" "  /* Definition of " FUTEX_* " constants */"
.BR "#include <sys/syscall.h>" "  /* Definition of " SYS_* " constants */"
.B #include <unistd.h>
.P
.BI "long syscall(SYS_futex, uint32_t *" uaddr ", FUTEX_REQUEUE,"
.BI "             uint32_t " val ", uint32_t " val2 ", uint32_t *" uaddr2 );
.fi
.SH DESCRIPTION
This operation performs the same task as
.BR FUTEX_CMP_REQUEUE (2const),
except that the futex word isn't compared.
.\"
.SH RETURN VALUE
On error,
\-1 is returned,
and
.I errno
is set to indicate the error.
.P
On success,
.B FUTEX_REQUEUE
returns the number of waiters that were woken up.
.SH ERRORS
See
.BR futex (2).
.TP
.B EFAULT
.I uaddr2
did not point to a valid user-space address.
.TP
.B EINVAL
.I uaddr2
does not point to a valid object\[em]that is,
the address is not four-byte-aligned.
.TP
.B EINVAL
The kernel detected an inconsistency between the user-space state at
.I uaddr
and the kernel state\[em]that is, it detected a waiter which waits in
.BR FUTEX_LOCK_PI (2const)
or
.BR FUTEX_LOCK_PI2 (2const)
on
.IR uaddr .
.SH STANDARDS
Linux.
.SH HISTORY
Linux 2.6.0.
.SH SEE ALSO
.BR futex (2)