IO_CANCEL(2)              (2020-12-21)               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
          Note: this page describes the raw Linux system call inter-
          face.  The wrapper function provided by libaio uses a dif-
          ferent type for the ctx_id argument.  See NOTES.

          The io_cancel() system call attempts to cancel an asyn-
          chronous 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 suc-
          cessfully canceled, the event will be copied into the memory
          pointed to by result without being placed into the comple-
          tion 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 pro-
          grams that are intended to be portable.

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     IO_CANCEL(2)              (2020-12-21)               IO_CANCEL(2)

     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
          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 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 indicat-
          ing 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 5.10 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 https://www.kernel.org/doc/man-pages/.

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