IO_CANCEL(2)                        Linux Programmer's Manual                        IO_CANCEL(2)



NAME
       io_cancel - cancel an outstanding asynchronous I/O operation

SYNOPSIS
       #include <linux/aio_abi.h>          /* Defines needed types */

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

       Note: There is no glibc wrapper for this system call; see NOTES.

DESCRIPTION
       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 oper‐
       ation 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.  For the failure return, see NOTES.

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
       The asynchronous I/O system calls first appeared in Linux 2.5.

CONFORMING TO
       io_cancel()  is  Linux-specific and should not be used in programs that are intended to be
       portable.

NOTES
       Glibc does not provide a wrapper function for this system call.  You could invoke it using
       syscall(2).   But  instead, you probably want to use the io_cancel() wrapper function pro‐
       vided by libaio.

       Note that the libaio wrapper function uses a different type (io_context_t) for the  ctx_id
       argument.   Note  also that the libaio wrapper does not follow the usual C library conven‐
       tions for indicating errors: on error it returns a negated error number (the  negative  of
       one  of  the values listed in ERRORS).  If the system call is invoked via syscall(2), then
       the return value follows the usual conventions for indicating an error: -1, with errno set
       to a (positive) value that indicates the error.

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

COLOPHON
       This  page  is  part of release 3.74 of the Linux man-pages project.  A description of the
       project, information about reporting bugs, and the latest version of  this  page,  can  be
       found at http://www.kernel.org/doc/man-pages/.



Linux                                       2013-04-10                               IO_CANCEL(2)