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       io_cancel - cancel an outstanding asynchronous I/O operation


       Standard C library (libc, -lc)

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


       #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);


       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 NOTES.

       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.


       On success, io_cancel() returns 0.  For the failure return, see NOTES.


       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.


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


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


       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.


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