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Clarify usage of aio(4) with kqueue(2)

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Reviewed by:	jhb
MFC after:	3 weeks
Differential Revision:	https://reviews.freebsd.org/D11299
This commit is contained in:
Alan Somers 2017-06-23 00:40:09 +00:00
parent 514fd0b8d3
commit 09986d3bd2
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=320255
2 changed files with 29 additions and 28 deletions
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37
lib/libc/sys/kqueue.2
View File

@ -24,7 +24,7 @@
.\"
.\" $FreeBSD$
.\"
.Dd June 17, 2017
.Dd June 22, 2017
.Dt KQUEUE 2
.Os
.Sh NAME
@ -351,33 +351,18 @@ case.
Takes a descriptor as the identifier, and returns whenever
there is no remaining data in the write buffer.
.It Dv EVFILT_AIO
The sigevent portion of the AIO request is filled in, with
.Va sigev_notify_kqueue
containing the descriptor of the kqueue that the event should
be attached to,
.Va sigev_notify_kevent_flags
containing the kevent flags which should be
.Dv EV_ONESHOT ,
.Dv EV_CLEAR
or
.Dv EV_DISPATCH ,
.Va sigev_value
containing the udata value, and
.Va sigev_notify
set to
.Dv SIGEV_KEVENT .
When the
.Fn aio_*
system call is made, the event will be registered
with the specified kqueue, and the
.Va ident
argument set to the
.Fa struct aiocb
returned by the
.Fn aio_*
system call.
Events for this filter are not registered with
.Fn kevent
directly but are registered via the
.Va aio_sigevent
member of an asychronous I/O request when it is scheduled via an asychronous I/O
system call such as
.Fn aio_read .
The filter returns under the same conditions as
.Fn aio_error .
For more details on this filter see
.Xr sigevent 3 and
.Xr aio 4 .
.It Dv EVFILT_VNODE
Takes a file descriptor as the identifier and the events to watch for in
.Va fflags ,

20
share/man/man4/aio.4
View File

@ -27,7 +27,7 @@
.\"
.\" $FreeBSD$
.\"
.Dd July 21, 2016
.Dd June 22, 2017
.Dt AIO 4
.Os
.Sh NAME
@ -161,11 +161,27 @@ field which can be used to request notification when an operation completes.
For
.Dv SIGEV_KEVENT
notifications,
the posted kevent will contain:
the
.Va sigevent
.Ap
s
.Va sigev_notify_kqueue
field should contain the descriptor of the kqueue that the event should be attached
to, its
.Va sigev_notify_kevent_flags
field may contain
.Dv EV_ONESHOT ,
.Dv EV_CLEAR , and/or
.Dv EV_DISPATCH , and its
.Va sigev_notify
field should be set to
.Dv SIGEV_KEVENT .
The posted kevent will contain:
.Bl -column ".Va filter"
.It Sy Member Ta Sy Value
.It Va ident Ta asynchronous I/O control buffer pointer
.It Va filter Ta Dv EVFILT_AIO
.It Va flags Ta Dv EV_EOF
.It Va udata Ta
value stored in
.Va aio_sigevent.sigev_value