MFC 302899: Add documentation for the sigevent structure.

- Add a sigevent(3) manpage to give a general overview of the sigevent
  structure and the available notification mechanisms.
- Document that AIO requests contain a nested sigevent structure that can
  be used to request completion notification.
- Expand the sigevent details in other manuals to note details such as
  the extra values stored in a queued signal's information or in a posted
  kevent.

Approved by:	re (gjb)

1 files changed, 12 insertions, 1 deletions

diff --git a/lib/libc/sys/aio_read.2 b/lib/libc/sys/aio_read.2
index 65b5e10..cc0133b 100644
--- a/lib/libc/sys/aio_read.2
+++ b/lib/libc/sys/aio_read.2
@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd November 17, 1998
+.Dd July 15, 2016
 .Dt AIO_READ 2
 .Os
 .Sh NAME
@@ -79,6 +79,12 @@ If the request is successfully enqueued, the value of
 .Fa iocb->aio_offset
 can be modified during the request as context, so this value must
 not be referenced after the request is enqueued.
+.Pp
+The
+.Fa iocb->aio_sigevent
+structure can be used to request notification of the request's
+completion as described in
+.Xr aio 4 .
 .Sh RESTRICTIONS
 The Asynchronous I/O Control Block structure pointed to by
 .Fa iocb
@@ -115,6 +121,10 @@ system call will fail if:
 .Bl -tag -width Er
 .It Bq Er EAGAIN
 The request was not queued because of system resource limitations.
+.It Bq Er EINVAL
+The asynchronous notification method in
+.Fa iocb->aio_sigevent.sigev_notify
+is invalid or not supported.
 .It Bq Er ENOSYS
 The
 .Fn aio_read
@@ -191,6 +201,7 @@ would be invalid.
 .Xr aio_suspend 2 ,
 .Xr aio_waitcomplete 2 ,
 .Xr aio_write 2 ,
+.Xr sigevent 3 ,
 .Xr siginfo 3 ,
 .Xr aio 4
 .Sh STANDARDS