.\" Copyright (C) 2003 Free Software Foundation, Inc.
+.\"
+.\" %%%LICENSE_START(GPL_NOVERSION_ONELINE)
.\" This file is distributed according to the GNU General Public License.
-.\" See the file COPYING in the top level source directory for details.
+.\" %%%LICENSE_END
.\"
-.\" .de Sh \" Subsection
-.\" .br
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-.\" .ne 5
-.\" .PP
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-.\" .PP
-.\" ..
-.\" .de Sp \" Vertical space (when we can't use .PP)
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-.\" .if n .sp
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-.TH IO_CANCEL 2 2008-06-18 "Linux" "Linux Programmer's Manual"
+.TH IO_CANCEL 2 2013-04-10 "Linux" "Linux Programmer's Manual"
.SH NAME
io_cancel \- cancel an outstanding asynchronous I/O operation
-.SH "SYNOPSIS"
+.SH SYNOPSIS
.nf
-.\" .ad l
-.\" .hy 0
-.\"
-.B #include <libaio.h>
-.\"#include <linux/aio.h>
-.sp
-.\" .HP 16
+.BR "#include <linux/aio_abi.h>" " /* Defines needed types */"
+
.BI "int io_cancel(aio_context_t " ctx_id ", struct iocb *" iocb ,
.BI " struct io_event *" result );
-.\" .ad
-.\" .hy
-.sp
-Link with \fI\-laio\fP.
.fi
-.SH "DESCRIPTION"
+
+.IR Note :
+There is no glibc wrapper for this system call; see NOTES.
+.SH DESCRIPTION
.PP
+The
.BR io_cancel ()
+system call
attempts to cancel an asynchronous I/O operation previously submitted with
.BR io_submit (2).
-\fIctx_id\fP is the AIO context ID of the operation to be canceled.
-If the AIO context is found, the event will be canceled and then copied
-into the memory pointed to by \fIresult\fP without being placed
-into the completion queue.
-.SH "RETURN VALUE"
+The
+.I iocb
+argument describes the operation to be canceled and the
+.I 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
+.I result
+without being placed into the
+completion queue.
+.SH RETURN VALUE
On success,
.BR io_cancel ()
returns 0.
For the failure return, see NOTES.
-.SH "ERRORS"
+.SH ERRORS
.TP
.B EAGAIN
The \fIiocb\fP specified was not canceled.
.B ENOSYS
.BR io_cancel ()
is not implemented on this architecture.
-.SH "VERSIONS"
+.SH VERSIONS
.PP
-The asynchronous I/O system calls first appeared in Linux 2.5, August 2002.
-.SH "CONFORMING TO"
+The asynchronous I/O system calls first appeared in Linux 2.5.
+.SH CONFORMING TO
.PP
.BR io_cancel ()
is Linux-specific and should not be used
in programs that are intended to be portable.
.SH NOTES
Glibc does not provide a wrapper function for this system call.
+You could invoke it using
+.BR syscall (2).
+But instead, you probably want to use the
+.BR io_cancel ()
+wrapper function provided by
+.\" http://git.fedorahosted.org/git/?p=libaio.git
+.IR libaio .
-The wrapper provided in
+Note that the
.I libaio
-for
-.BR io_cancel ()
-does not follow the usual C library conventions for indicating error:
+wrapper function uses a different type
+.RI ( io_context_t )
+.\" But glibc is confused, since <libaio.h> uses 'io_context_t' to declare
+.\" the system call.
+for the
+.I ctx_id
+argument.
+Note also that the
+.I 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
indicating an error: \-1, with
.I errno
set to a (positive) value that indicates the error.
-.SH "SEE ALSO"
+.SH SEE ALSO
.BR io_destroy (2),
.BR io_getevents (2),
.BR io_setup (2),
-.BR io_submit (2)
-.\" .SH "NOTES"
-.\"
-.\" .PP
-.\" The asynchronous I/O system calls were written by Benjamin LaHaise.
-.\"
+.BR io_submit (2),
+.BR aio (7)
.\" .SH AUTHOR
.\" Kent Yoder.
+.SH COLOPHON
+This page is part of release 3.79 of the Linux
+.I 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/.
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