io_cancel(2)                  System Calls Manual                 io_cancel(2)

NAME
       io_cancel - cancel an outstanding asynchronous I/O operation

LIBRARY
       Standard C library (libc, -lc)

SYNOPSIS
       #include <linux/aio_abi.h>    /* Definition of needed types */
       #include <sys/syscall.h>      /* Definition of SYS_* constants */
       #include <unistd.h>

       int syscall(SYS_io_cancel, aio_context_t ctx_id, struct iocb *iocb,
                   struct io_event *result);

DESCRIPTION
       Note: you probably want to use the io_getevents(3) wrapper function
       provided by libaio; see VERSIONS.

       The io_cancel() system call attempts to cancel an asynchronous I/O
       operation previously submitted with io_submit(2).  The iocb argument
       describes the operation to be canceled and the ctx_id argument is the
       AIO context to which the operation was submitted.  If the operation is
       successfully canceled, the event will be copied into the memory pointed
       to by result without being placed into the completion queue.

RETURN VALUE
       On success, io_cancel() returns 0.  On error, -1 is returned, and errno
       is set to indicate the error.

ERRORS
       EAGAIN The iocb specified was not canceled.

       EFAULT One of the data structures points to invalid data.

       EINVAL The AIO context specified by ctx_id is invalid.

       ENOSYS io_cancel() is not implemented on this architecture.

VERSIONS
       libaio <https://pagure.io/libaio> provides a wrapper function with the
       same name, but different prototype and return value.  You probably want
       to use that wrapper.

STANDARDS
       Linux.

HISTORY
       Linux 2.5.

SEE ALSO
       io_destroy(2), io_getevents(2), io_setup(2), io_submit(2),
       io_cancel(3), aio(7)

Linux man-pages 6.19              2026-04-11                      io_cancel(2)