NAME

       io_cancel - cancel an outstanding asynchronous I/O operation

LIBRARY

       Standard C library (libc, -lc)

       Alternatively, Asynchronous I/O library (libaio, -laio); see VERSIONS.

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:  this  page  describes  the  raw  Linux system call interface.  The wrapper function
       provided by libaio uses a different type for the ctx_id argument.  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.  For the failure return, see VERSIONS.

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

       You probably want to use the io_cancel() wrapper function provided 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
       conventions 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.

STANDARDS

       Linux.

HISTORY

       Linux 2.5.

SEE ALSO

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