kern/54707: Description for SI_ASYNCIO in siginfo(2) outdated

[rokuyama.rk%gmail.com@localhost]

>Number:         54707
>Category:       kern
>Synopsis:       Description for SI_ASYNCIO in siginfo(2) outdated
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Nov 18 11:00:00 +0000 2019
>Originator:     Rin Okuyama
>Release:        9.99.17
>Organization:
Department of Physics, Meiji University
>Environment:
NetBSD nb64 9.99.17 NetBSD 9.99.17 (AMD64) #11: Mon Nov 18 18:48:19 JST 2019  rin@latipes:/build/src/sys/arch/amd64/compile/AMD64 amd64
>Description:
siginfo(2) explains SI_ASYNCIO as:

https://netbsd.gw.com/cgi-bin/man-cgi?siginfo++NetBSD-current

SI_ASYNCIO  The signal was generated by completion of an asynchronous I/O
            operation.  The siginfo structure contains the following
            additional members:

                  int si_fd;
                  long si_band;
<snip>

However, only si_value is used for SI_ASYNCIO. There's 3 files in
kernel that use SI_ASYNCIO: kern/sys_aio.c and
compat/linux{,32}/common/linux{,32}_signal.c. Everyone fills only
si_value member. For userland, kdump(1) recognizes SI_ASYNCIO, and
it retrieves only si_value also.
>How-To-Repeat:
Code reading.
>Fix:
Please update siginfo(2) with description of si_value member.