[PATCH] Document struct sigevent in sigevent(7)

[PATCH] Document struct sigevent in sigevent(7)

[Petr Baudis]

The sigevent structure is used as a common interface for several
asynchronous pthreads functions; also, getaddrinfo_a() uses it
and in the future, other library functions might.

Currently, it is completely non-descript in some cases, plus
there are two competing descriptions in timer_create(2) and
mq_notify(3) (the former appears to be based on the latter).
This patch attempts to unify the descriptions in a single
manual page and networks it to the rest, so that I do not
have to add yet another description for the getaddrinfo_a(3)
manual page (currently in the works).

P.S.: There are two unresolved issues with this patch - the
timer_create(2) requirement of real-time signal requirements
is somewhat confusing and it seems that SIGEV_THREAD_ID can
be or'd with SIGEV_SIGNAL or not. I did not have time to research
this so far, so I decided to rather send it in and see if someone
knows about this off the top of their head.

Signed-off-by: Petr Baudis <pasky-AlSwsSmVLrQ@public.gmane.org>

diff --git a/man2/timer_create.2 b/man2/timer_create.2
index 92178e0..8f7c4d2 100644
--- a/man2/timer_create.2
+++ b/man2/timer_create.2
@@ -88,92 +88,21 @@ or
 The
 .I evp
 argument points to a
-.I sigevent
+.IR sigevent (7)
 structure that specifies how the caller
 should be notified when the timer expires.
-This structure is defined something like the following:
-
-.in +4n
-.nf
-union sigval {
-    int   sival_int;
-    void *sival_ptr;
-};
-
-struct sigevent {
-    int          sigev_notify;    /* Notification method */
-    int          sigev_signo;     /* Timer expiration signal */
-    union sigval sigev_value;     /* Value accompanying signal or
-                                     passed to thread function */
-    void       (*sigev_notify_function) (union sigval);
-                   /* Function used for thread
-                      notifications (SIGEV_THREAD) */
-    void        *sigev_notify_attributes;
-                   /* Attributes for notification thread
-                      (SIGEV_THREAD) */
-    pid_t        sigev_notify_thread_id;
-                   /* ID of thread to signal (SIGEV_THREAD_ID) */
-};
-.fi
-.in
-
-Some of these fields may be defined as part of a union:
-a program should only employ those fields relevant
-to the value specified in
-.IR sigev_notify .
-This field can have the following values:
-.TP
-.BR SIGEV_NONE
-Don't asynchronously notify when the timer expires.
-Progress of the timer can be monitored using
+In case its
+.I sigev_notify
+field is set to
+.BR SIGEV_NONE ,
+the progress of the timer can be monitored using
 .BR timer_gettime (2).
-.TP
+If the
 .BR SIGEV_SIGNAL
-Upon timer expiration, generate the signal
-.I sigev_signo
-for the process.
-If
-.I sigev_signo
-is a real-time signal,
-then it will be accompanied by the data specified in
-.IR sigev_value
-(like the signal-accompanying data for
-.BR sigqueue (2)).
-At any point in time,
+notification is used, at any point in time
 at most one signal is queued to the process for a given timer; see
 .BR timer_getoverrun (2)
 for more details.
-.TP
-.BR SIGEV_THREAD
-Upon timer expiration, invoke
-.I sigev_notify_function
-as if it were the start function of a new thread.
-(Among the implementation possibilities here are that
-each timer notification could result in the creation of a new thread,
-or that a single thread is created to receive all notifications.)
-The function is invoked with
-.I sigev_value
-as its sole argument.
-If
-.I sigev_notify_attributes
-is not NULL, it should point to a
-.I pthread_attr_t
-structure that defines attributes for the new thread (see
-.BR pthread_attr_init (3).
-.TP
-.BR SIGEV_THREAD_ID " (Linux-specific)"
-As for
-.BR SIGEV_SIGNAL ,
-but the signal is targeted at the thread whose ID is given in
-.IR sigev_notify_thread_id ,
-which must be a thread in the same process as the caller.
-The
-.IR sigev_notify_thread_id
-field specifies a kernel thread ID, that is, the value returned by
-.BR clone (2)
-or
-.BR gettid (2).
-This flag is only intended for use by threading libraries.
 .PP
 Specifying
 .I evp
@@ -431,4 +360,5 @@ main(int argc, char *argv[])
 .BR pthread_getcpuclockid (3),
 .BR pthreads (7),
 .BR signal (7),
+.BR sigevent (7),
 .BR time (7)
diff --git a/man3/aio_fsync.3 b/man3/aio_fsync.3
index cd9afc9..8babcd1 100644
--- a/man3/aio_fsync.3
+++ b/man3/aio_fsync.3
@@ -58,7 +58,9 @@ the only field in the structure pointed to by
 .I aiocbp
 that is used by this call is the
 .I aio_sigevent
-field (a \fIstruct sigevent\fP) that indicates the desired type of
+field (pointer to a
+.IR sigevent (7)
+structure) that indicates the desired type of
 asynchronous notification at completion.
 All other fields are ignored.
 .SH "RETURN VALUE"
@@ -91,4 +93,5 @@ POSIX.1-2001.
 .BR aio_read (3),
 .BR aio_return (3),
 .BR aio_suspend (3),
-.BR aio_write (3)
+.BR aio_write (3),
+.BR sigevent (7)
diff --git a/man3/mq_notify.3 b/man3/mq_notify.3
index 1b5df1a..a499bf8 100644
--- a/man3/mq_notify.3
+++ b/man3/mq_notify.3
@@ -44,90 +44,12 @@ the empty message queue referred to by the descriptor
 The
 .I notification
 argument is a pointer to a
-.I sigevent
-structure that is defined something like the following:
-.in +4n
-.nf
-
-union sigval {          /* Data passed with notification */
-    int     sival_int;         /* Integer value */
-    void   *sival_ptr;         /* Pointer value */
-};
-
-struct sigevent {
-    int          sigev_notify; /* Notification method */
-    int          sigev_signo;  /* Notification signal */
-    union sigval sigev_value;  /* Data passed with
-                                  notification */
-    void       (*sigev_notify_function) (union sigval);
-                               /* Function for thread
-                                  notification */
-    void        *sigev_notify_attributes;
-                               /* Thread function attributes */
-};
-.fi
-.in
-.PP
-If
+.IR sigevent (7)
+structure.  If
 .I notification
 is a non-NULL pointer, then
 .BR mq_notify ()
 registers the calling process to receive message notification.
-The
-.I sigev_notify
-field of the
-.I sigevent
-to which
-.I notification
-points specifies how notification is to be performed.
-This field has one of the following values:
-.TP
-.B SIGEV_NONE
-A "null" notification: the calling process is registered as the target
-for notification, but when a message arrives, no notification is sent.
-.\" When is SIGEV_NONE useful?
-.TP
-.B SIGEV_SIGNAL
-Notify the process by sending the signal specified in
-.IR sigev_signo .
-If the signal is caught with a signal handler that
-was registered using the
-.BR sigaction (2)
-.B SA_SIGINFO
-flag, then the following fields are set in the
-.I siginfo_t
-structure that is passed as the second argument of the handler:
-.I si_code
-is set to
-.BR SI_MESGQ ;
-.I si_signo
-is set to the signal number;
-.I si_value
-is set to the value specified in
-.IR notification\->sigev_value ;
-.\" I don't know of other implementations that set
-.\" si_pid and si_uid -- MTK
-.I si_pid
-is set to the PID of the process that sent the message; and
-.I si_uid
-is set to the real user ID of the sending process.
-The same information is available if the signal is accepted using
-.BR sigwaitinfo (2).
-.TP
-.B SIGEV_THREAD
-Deliver notification by invoking
-.I notification\->sigev_notify_function
-as the start function of a new thread.
-The function is invoked with
-.I notification\->sigev_value
-as its sole argument.
-If
-.I notification\->sigev_notify_attributes
-is not NULL, then it should point to a
-.I pthread_attr_t
-structure that defines attributes for the thread (see
-.BR pthread_attr_init (3)).
-.PP
 Only one process can be registered to receive notification
 from a message queue.
 
@@ -266,4 +188,5 @@ main(int argc, char *argv[])
 .BR mq_receive (3),
 .BR mq_send (3),
 .BR mq_unlink (3),
-.BR mq_overview (7)
+.BR mq_overview (7),
+.BR sigevent (7)
diff --git a/man7/sigevent.7 b/man7/sigevent.7
index e69de29..0434440 100644
--- a/man7/sigevent.7
+++ b/man7/sigevent.7
@@ -0,0 +1,137 @@
+.\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
+.\" Copyright (C) 2009 Petr Baudis <pasky-AlSwsSmVLrQ@public.gmane.org>
+.\"
+.\" Permission is granted to make and distribute verbatim copies of this
+.\" manual provided the copyright notice and this permission notice are
+.\" preserved on all copies.
+.\"
+.\" Permission is granted to copy and distribute modified versions of this
+.\" manual under the conditions for verbatim copying, provided that the
+.\" entire resulting derived work is distributed under the terms of a
+.\" permission notice identical to this one.
+.\"
+.\" Since the Linux kernel and libraries are constantly changing, this
+.\" manual page may be incorrect or out-of-date.  The author(s) assume no
+.\" responsibility for errors or omissions, or for damages resulting from
+.\" the use of the information contained herein.  The author(s) may not
+.\" have taken the same level of care in the production of this manual,
+.\" which is licensed free of charge, as they might when working
+.\" professionally.
+.\"
+.\" Formatted or processed versions of this manual, if unaccompanied by
+.\" the source, must acknowledge the copyright and authors of this work.
+.\"
+.TH SIGEVENT 3 2009-04-08 "GNU" "Linux Programmer's Manual"
+.SH NAME
+struct sigevent \- structure for notification from asynchronous routines
+.SH SYNOPSIS
+.nf
+
+union sigval {          /* Data passed with notification */
+    int     sival_int;         /* Integer value */
+    void   *sival_ptr;         /* Pointer value */
+};
+
+struct sigevent {
+    int          sigev_notify; /* Notification method */
+    int          sigev_signo;  /* Notification signal */
+    union sigval sigev_value;  /* Data passed with
+                                  notification */
+    void       (*sigev_notify_function) (union sigval);
+                   /* Function used for thread
+                      notification (SIGEV_THREAD) */
+    void        *sigev_notify_attributes;
+                   /* Attributes for notification thread
+                      (SIGEV_THREAD) */
+    pid_t        sigev_notify_thread_id;
+                   /* ID of thread to signal (SIGEV_THREAD_ID) */
+};
+.fi
+.SH DESCRIPTION
+.PP
+This structure is used by various modern asynchronous routines
+(mainly, but not exclusively, those of POSIX threads API),
+to describe the way a process wishes to be notified about
+the progress of the routine.
+.PP
+Some of these fields may be defined as part of a union:
+a program should only employ those fields relevant
+to the value specified in
+.IR sigev_notify .
+.PP
+The
+.I sigev_notify
+field specifies how notification is to be performed.
+This field can have one of the following values:
+.TP
+.BR SIGEV_NONE
+A "null" notification: the calling process is registered as the target
+for notification, but when a message arrives, no notification is sent.
+.TP
+.BR SIGEV_SIGNAL
+Notify the process by sending the signal specified in
+.IR sigev_signo .
+If the signal is caught with a signal handler that
+was registered using the
+.BR sigaction (2)
+.B SA_SIGINFO
+flag, then the following fields are set in the
+.I siginfo_t
+structure that is passed as the second argument of the handler:
+.\" Does this happen only for real-time signals? Or only in case of timer_create()?
+.I si_code
+is set appropriately based on the called routine;
+.I si_signo
+is set to the signal number;
+.I si_value
+is set to the value specified in
+.IR sigev_value ;
+.\" I don't know of other implementations that set
+.\" si_pid and si_uid -- MTK
+.I si_pid
+is set to the PID of the process that sent the message; and
+.I si_uid
+is set to the real user ID of the sending process.
+The same information is available if the signal is accepted using
+.BR sigwaitinfo (2).
+.TP
+.BR SIGEV_THREAD
+Deliver the notification by invoking
+.I sigev_notify_function
+as if it were the start function of a new thread.
+(Among the implementation possibilities here are that
+each timer notification could result in the creation of a new thread,
+or that a single thread is created to receive all notifications.)
+The function is invoked with
+.I sigev_value
+as its sole argument.
+If
+.I sigev_notify_attributes
+is not NULL, it should point to a
+.I pthread_attr_t
+structure that defines attributes for the new thread (see
+.BR pthread_attr_init (3)).
+.TP
+.\" | SIGEV_SIGNAL vs not?
+.BR SIGEV_THREAD_ID " (Linux-specific)"
+As for
+.BR SIGEV_SIGNAL ,
+but the signal is targeted at the thread whose ID is given in
+.IR sigev_notify_thread_id ,
+which must be a thread in the same process as the caller.
+The
+.IR sigev_notify_thread_id
+field specifies a kernel thread ID, that is, the value returned by
+.BR clone (2)
+or
+.BR gettid (2).
+This value is only intended for use by threading libraries.
+.SH CONFORMING TO
+POSIX.1-2001.
+.SH "SEE ALSO"
+.BR mq_notify (3),
+.BR timer_create (2),
+.BR aio_fsync (3),
+.BR lio_listio (3),
+.BR getaddrinfo_a (3),
+.BR pthreads (7)
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Re: [PATCH] Document struct sigevent in sigevent(7)

[Petr Baudis]

On Wed, Apr 15, 2009 at 01:14:42PM +0200, Petr Baudis wrote:
> The sigevent structure is used as a common interface for several
> asynchronous pthreads functions; also, getaddrinfo_a() uses it
> and in the future, other library functions might.
> 
> Currently, it is completely non-descript in some cases, plus
> there are two competing descriptions in timer_create(2) and
> mq_notify(3) (the former appears to be based on the latter).
> This patch attempts to unify the descriptions in a single
> manual page and networks it to the rest, so that I do not
> have to add yet another description for the getaddrinfo_a(3)
> manual page (currently in the works).
> 
> P.S.: There are two unresolved issues with this patch - the
> timer_create(2) requirement of real-time signal requirements
> is somewhat confusing and it seems that SIGEV_THREAD_ID can
> be or'd with SIGEV_SIGNAL or not. I did not have time to research
> this so far, so I decided to rather send it in and see if someone
> knows about this off the top of their head.
> 
> Signed-off-by: Petr Baudis <pasky-AlSwsSmVLrQ@public.gmane.org>

Ping...

				Petr "Pasky" Baudis
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Re: [PATCH] Document struct sigevent in sigevent(7)

[Petr Baudis]

On Sun, Sep 20, 2009 at 05:05:00PM +0200, Petr Baudis wrote:
> On Wed, Apr 15, 2009 at 01:14:42PM +0200, Petr Baudis wrote:
> > The sigevent structure is used as a common interface for several
> > asynchronous pthreads functions; also, getaddrinfo_a() uses it
> > and in the future, other library functions might.
> > 
> > Currently, it is completely non-descript in some cases, plus
> > there are two competing descriptions in timer_create(2) and
> > mq_notify(3) (the former appears to be based on the latter).
> > This patch attempts to unify the descriptions in a single
> > manual page and networks it to the rest, so that I do not
> > have to add yet another description for the getaddrinfo_a(3)
> > manual page (currently in the works).
> > 
> > P.S.: There are two unresolved issues with this patch - the
> > timer_create(2) requirement of real-time signal requirements
> > is somewhat confusing and it seems that SIGEV_THREAD_ID can
> > be or'd with SIGEV_SIGNAL or not. I did not have time to research
> > this so far, so I decided to rather send it in and see if someone
> > knows about this off the top of their head.
> > 
> > Signed-off-by: Petr Baudis <pasky-AlSwsSmVLrQ@public.gmane.org>
> 
> Ping...

Ping... :-)

P.S.: I'm sorry that I have not been of any help with maintaining
manpages contrary to what I promised - it turns out I'm currently way
too swamped by other stuff.. :-(

-- 
				Petr "Pasky" Baudis
A great many people think they are thinking when they are merely
rearranging their prejudices. -- William James
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Re: [PATCH] Document struct sigevent in sigevent(7)

[Michael Kerrisk]

Hello Petr,

First of all, my apologies for the enormous delay on following up on this patch.

On Wed, Apr 15, 2009 at 1:14 PM, Petr Baudis <pasky-AlSwsSmVLrQ@public.gmane.org> wrote:
> The sigevent structure is used as a common interface for several
> asynchronous pthreads functions; also, getaddrinfo_a() uses it
> and in the future, other library functions might.
>
> Currently, it is completely non-descript in some cases, plus
> there are two competing descriptions in timer_create(2) and
> mq_notify(3) (the former appears to be based on the latter).
> This patch attempts to unify the descriptions in a single
> manual page and networks it to the rest, so that I do not
> have to add yet another description for the getaddrinfo_a(3)
> manual page (currently in the works).
>
> P.S.: There are two unresolved issues with this patch - the
> timer_create(2) requirement of real-time signal requirements
> is somewhat confusing and it seems that SIGEV_THREAD_ID can
> be or'd with SIGEV_SIGNAL or not. I did not have time to research
> this so far, so I decided to rather send it in and see if someone
> knows about this off the top of their head.

I understand your motivations for writing this patch, in terms of
eliminating redundancy, and possible out-of-syncness in various pages.
However,  this patch suffers from several of the problems that I aimed
to avoid when I added the timer_create.2 page:

* By the nature of the APIs, the descriptions need to add some
API-specific content for the various 'notification' values. Your patch
partially addresses that, but in unifying the content, it loses some
per-API information.

* The patch introduces incorrect information. E.g., for SIGEV_SIGNAL,
not all APIs set si_uid and si_pid. Message queues do, but POSIX
timers don't (it makes no sense)

* Not all 'notification' values are valid for all APIS. As far as I
know, SIGEV_THREAD_ID is valid only for POSIX timers.

Like I say, when I wrote the timer_create.2 page, I ran into the same
problems, which is why I partially duplicated content, rather than
writing a separate page. Of course, this solution doesn't scale well,
as you highlight. So I think your idea is the right way to go, but it
needs tweaking. I propose to add the version below. Comments welcome.

Thanks,

Michael


.\" Copyright (C) 2006, 2010 Michael Kerrisk <mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
.\" Copyright (C) 2009 Petr Baudis <pasky-AlSwsSmVLrQ@public.gmane.org>
.\"
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\"
.TH SIGEVENT 7 2010-09-19 "GNU" "Linux Programmer's Manual"
.SH NAME
struct sigevent \- structure for notification from asynchronous routines
.SH SYNOPSIS
.nf

union sigval {          /* Data passed with notification */
    int     sival_int;         /* Integer value */
    void   *sival_ptr;         /* Pointer value */
};

struct sigevent {
    int          sigev_notify; /* Notification method */
    int          sigev_signo;  /* Notification signal */
    union sigval sigev_value;  /* Data passed with
                                  notification */
    void       (*sigev_notify_function) (union sigval);
                     /* Function used for thread
                        notification (SIGEV_THREAD) */
    void        *sigev_notify_attributes;
                     /* Attributes for notification thread
                        (SIGEV_THREAD) */
    pid_t        sigev_notify_thread_id;
                     /* ID of thread to signal (SIGEV_THREAD_ID) */
};
.fi
.SH DESCRIPTION
.PP
The
.I sigevent
structure is used by various APIs
to describe the way a process is to be notified about an event
(e.g., completion of an asynchronous request, expiration of a timer,
or the arrival of a message).
.PP
The definition shown in the SYNOPSIS is approximate:
some of the fields in the
.I sigevent
structure may be defined as part of a union.
Programs should only employ those fields relevant
to the value specified in
.IR sigev_notify .
.PP
The
.I sigev_notify
field specifies how notification is to be performed.
This field can have one of the following values:
.TP 8
.BR SIGEV_NONE
A "null" notification: don't do anything when the event occurs.
.TP
.BR SIGEV_SIGNAL
Notify the process by sending the signal specified in
.IR sigev_signo .
.IP
If the signal is caught with a signal handler that was registered using the
.BR sigaction (2)
.B SA_SIGINFO
flag, then the following fields are set in the
.I siginfo_t
structure that is passed as the second argument of the handler:
.RS 8
.TP 10
.I si_code
This field is set to a value that depends on the API
delivering the notification.
.TP
.I si_signo
This field is set to the signal number (i.e., the same value as in
.IR sigev_signo ).
.TP
.I si_value
This field is set to the value specified in
.IR sigev_value .
.RE
.IP
Depending on the API, other fields may also be set in the
.I siginfo_t
structure.
.IP
The same information is also available if the signal is accepted using
.BR sigwaitinfo (2).
.TP
.BR SIGEV_THREAD
Notify the process by invoking
.I sigev_notify_function
"as if" it were the start function of a new thread.
(Among the implementation possibilities here are that
each timer notification could result in the creation of a new thread,
or that a single thread is created to receive all notifications.)
The function is invoked with
.I sigev_value
as its sole argument.
If
.I sigev_notify_attributes
is not NULL, it should point to a
.I pthread_attr_t
structure that defines attributes for the new thread (see
.BR pthread_attr_init (3)).
.TP
.BR SIGEV_THREAD_ID " (Linux-specific)"
.\" | SIGEV_SIGNAL vs not?
Currently used only by POSIX timers; see
.BR timer_create (2).
.SH CONFORMING TO
POSIX.1-2001.
.SH "SEE ALSO"
.BR timer_create (2),
.BR aio_fsync (3),
.\" .BR lio_listio (3),
.\" FIXME This page will be added later .BR getaddrinfo_a (3),
.BR mq_notify (3),
.BR pthreads (7)
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Re: [PATCH] Document struct sigevent in sigevent(7)

[Michael Kerrisk]

Hello Petr,

The corresponding patch elsewhere in the set would then be as below.
Again, comments welcome.

Cheers,

Michael


diff --git a/man2/timer_create.2 b/man2/timer_create.2
index f5b8847..93af539 100644
--- a/man2/timer_create.2
+++ b/man2/timer_create.2
@@ -20,7 +20,7 @@
 .\"
 .\" Formatted or processed versions of this manual, if unaccompanied by
 .\" the source, must acknowledge the copyright and authors of this work.
-.TH TIMER_CREATE 2 2009-02-20 Linux "Linux Programmer's Manual"
+.TH TIMER_CREATE 2 2010-09-19 Linux "Linux Programmer's Manual"
 .SH NAME
 timer_create \- create a POSIX per-process timer
 .SH SYNOPSIS
@@ -90,37 +90,12 @@ argument points to a
 .I sigevent
 structure that specifies how the caller
 should be notified when the timer expires.
-This structure is defined something like the following:
+For the definition and general details of this structure, see
+.BR sigevent (7).

-.in +4n
-.nf
-union sigval {
-    int   sival_int;
-    void *sival_ptr;
-};
-
-struct sigevent {
-    int          sigev_notify;    /* Notification method */
-    int          sigev_signo;     /* Timer expiration signal */
-    union sigval sigev_value;     /* Value accompanying signal or
-                                     passed to thread function */
-    void       (*sigev_notify_function) (union sigval);
-                   /* Function used for thread
-                      notifications (SIGEV_THREAD) */
-    void        *sigev_notify_attributes;
-                   /* Attributes for notification thread
-                      (SIGEV_THREAD) */
-    pid_t        sigev_notify_thread_id;
-                   /* ID of thread to signal (SIGEV_THREAD_ID) */
-};
-.fi
-.in
-
-Some of these fields may be defined as part of a union:
-a program should only employ those fields relevant
-to the value specified in
-.IR sigev_notify .
-This field can have the following values:
+The
+.I evp.sigev_notify
+field can have the following values:
 .TP
 .BR SIGEV_NONE
 Don't asynchronously notify when the timer expires.
@@ -131,13 +106,15 @@ Progress of the timer can be monitored using
 Upon timer expiration, generate the signal
 .I sigev_signo
 for the process.
-If
-.I sigev_signo
-is a real-time signal,
-then it will be accompanied by the data specified in
-.IR sigev_value
-(like the signal-accompanying data for
-.BR sigqueue (2)).
+See
+.BR sigevent (7)
+for general details.
+The
+.I si_code
+field of the
+.I siginfo_t
+structure will be set to
+.BR SI_TIMER .
 At any point in time,
 at most one signal is queued to the process for a given timer; see
 .BR timer_getoverrun (2)
@@ -147,18 +124,9 @@ for more details.
 Upon timer expiration, invoke
 .I sigev_notify_function
 as if it were the start function of a new thread.
-(Among the implementation possibilities here are that
-each timer notification could result in the creation of a new thread,
-or that a single thread is created to receive all notifications.)
-The function is invoked with
-.I sigev_value
-as its sole argument.
-If
-.I sigev_notify_attributes
-is not NULL, it should point to a
-.I pthread_attr_t
-structure that defines attributes for the new thread (see
-.BR pthread_attr_init (3)).
+See
+.BR sigevent (7)
+for details.
 .TP
 .BR SIGEV_THREAD_ID " (Linux-specific)"
 As for
@@ -430,5 +398,6 @@ main(int argc, char *argv[])
 .BR clock_getcpuclockid (3),
 .BR pthread_getcpuclockid (3),
 .BR pthreads (7),
+.BR sigevent (7),
 .BR signal (7),
 .BR time (7)
diff --git a/man3/aio_fsync.3 b/man3/aio_fsync.3
index cd9afc9..949d02d 100644
--- a/man3/aio_fsync.3
+++ b/man3/aio_fsync.3
@@ -20,7 +20,7 @@
 .\" Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111,
 .\" USA.
 .\"
-.TH AIO_FSYNC 3 2003-11-14  "" "Linux Programmer's Manual"
+.TH AIO_FSYNC 3 2010-09-19  "" "Linux Programmer's Manual"
 .SH NAME
 aio_fsync \- asynchronous file synchronization
 .SH SYNOPSIS
@@ -58,8 +58,12 @@ the only field in the structure pointed to by
 .I aiocbp
 that is used by this call is the
 .I aio_sigevent
-field (a \fIstruct sigevent\fP) that indicates the desired type of
-asynchronous notification at completion.
+field (a
+.I sigevent
+structure, described in
+.BR sigevent (7)),
+which indicates the desired type of asynchronous notification at completion.
+,\" FIXME more sigevent details are probably needed here.
 All other fields are ignored.
 .SH "RETURN VALUE"
 On success (the sync request was successfully queued)
@@ -91,4 +95,5 @@ POSIX.1-2001.
 .BR aio_read (3),
 .BR aio_return (3),
 .BR aio_suspend (3),
-.BR aio_write (3)
+.BR aio_write (3),
+.BR sigevent (7)
diff --git a/man3/mq_notify.3 b/man3/mq_notify.3
index fba2d8f..f387f42 100644
--- a/man3/mq_notify.3
+++ b/man3/mq_notify.3
@@ -23,7 +23,7 @@
 .\" Formatted or processed versions of this manual, if unaccompanied by
 .\" the source, must acknowledge the copyright and authors of this work.
 .\"
-.TH MQ_NOTIFY 3 2010-08-29 "Linux" "Linux Programmer's Manual"
+.TH MQ_NOTIFY 3 2010-09-19 "Linux" "Linux Programmer's Manual"
 .SH NAME
 mq_notify \- register for notification when a message is available
 .SH SYNOPSIS
@@ -45,28 +45,9 @@ The
 .I notification
 argument is a pointer to a
 .I sigevent
-structure that is defined something like the following:
-.in +4n
-.nf
-
-union sigval {          /* Data passed with notification */
-    int     sival_int;         /* Integer value */
-    void   *sival_ptr;         /* Pointer value */
-};
-
-struct sigevent {
-    int          sigev_notify; /* Notification method */
-    int          sigev_signo;  /* Notification signal */
-    union sigval sigev_value;  /* Data passed with
-                                  notification */
-    void       (*sigev_notify_function) (union sigval);
-                               /* Function for thread
-                                  notification */
-    void        *sigev_notify_attributes;
-                               /* Thread function attributes */
-};
-.fi
-.in
+structure.
+For the definition and general details of this structure, see
+.BR sigevent (7).
 .PP
 If
 .I notification
@@ -77,7 +58,7 @@ The
 .I sigev_notify
 field of the
 .I sigevent
-to which
+structure to which
 .I notification
 points specifies how notification is to be performed.
 This field has one of the following values:
@@ -90,43 +71,30 @@ for notification, but when a message arrives, no
notification is sent.
 .B SIGEV_SIGNAL
 Notify the process by sending the signal specified in
 .IR sigev_signo .
-If the signal is caught with a signal handler that
-was registered using the
-.BR sigaction (2)
-.B SA_SIGINFO
-flag, then the following fields are set in the
-.I siginfo_t
-structure that is passed as the second argument of the handler:
+See
+.BR sigevent (7)
+for general details.
+The
 .I si_code
-is set to
-.BR SI_MESGQ ;
-.I si_signo
-is set to the signal number;
-.I si_value
-is set to the value specified in
-.IR notification\->sigev_value ;
+field of the
+.I siginfo_t
+structure will be set to
+.BR SI_MESGQ .
+In addition,
 .\" I don't know of other implementations that set
 .\" si_pid and si_uid -- MTK
 .I si_pid
-is set to the PID of the process that sent the message; and
+will be set to the PID of the process that sent the message, and
 .I si_uid
-is set to the real user ID of the sending process.
-The same information is available if the signal is accepted using
-.BR sigwaitinfo (2).
+will be set to the real user ID of the sending process.
 .TP
 .B SIGEV_THREAD
-Deliver notification by invoking
-.I notification\->sigev_notify_function
-as the start function of a new thread.
-The function is invoked with
-.I notification\->sigev_value
-as its sole argument.
-If
-.I notification\->sigev_notify_attributes
-is not NULL, then it should point to a
-.I pthread_attr_t
-structure that defines attributes for the thread (see
-.BR pthread_attr_init (3)).
+Upon message delivery, invoke
+.I sigev_notify_function
+as if it were the start function of a new thread.
+See
+.BR sigevent (7)
+for details.
 .PP
 Only one process can be registered to receive notification
 from a message queue.
@@ -279,4 +247,5 @@ main(int argc, char *argv[])
 .BR mq_receive (3),
 .BR mq_send (3),
 .BR mq_unlink (3),
-.BR mq_overview (7)
+.BR mq_overview (7),
+.BR sigevent (7)
diff --git a/man7/signal.7 b/man7/signal.7
index d67c893..8c418f8 100644
--- a/man7/signal.7
+++ b/man7/signal.7
@@ -41,7 +41,7 @@
 .\"     Added section on stop/cont signals interrupting syscalls.
 .\" 2008-10-05, mtk: various additions
 .\"
-.TH SIGNAL 7  2010-06-12 "Linux" "Linux Programmer's Manual"
+.TH SIGNAL 7  2010-09-19 "Linux" "Linux Programmer's Manual"
 .SH NAME
 signal \- overview of signals
 .SH DESCRIPTION
@@ -873,4 +873,5 @@ signal 29 is
 .BR sysv_signal (3),
 .BR core (5),
 .BR proc (5),
-.BR pthreads (7)
+.BR pthreads (7),
+.BR sigevent (7)
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Re: [PATCH] Document struct sigevent in sigevent(7)

[Petr Baudis]

  Hi!

On Sun, Sep 19, 2010 at 06:23:03PM +0200, Michael Kerrisk wrote:
> Like I say, when I wrote the timer_create.2 page, I ran into the same
> problems, which is why I partially duplicated content, rather than
> writing a separate page. Of course, this solution doesn't scale well,
> as you highlight. So I think your idea is the right way to go, but it
> needs tweaking. I propose to add the version below. Comments welcome.

  Hmm, what you write makes a lot of sense, the new versions looks good
to me!

  Thanks for looking into it,

-- 
				Petr "Pasky" Baudis
The true meaning of life is to plant a tree under whose shade
you will never sit.
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