kern/44986: "screens" gets stuck during detach

[tron%zhadum.org.uk@localhost]

>Number:         44986
>Category:       kern
>Synopsis:       "screens" gets stuck during detach
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat May 21 11:40:01 +0000 2011
>Originator:     tron%zhadum.org.uk@localhost
>Release:        NetBSD 5.99.51 2011-05-21 sources
>Organization:
Matthias Scheler                                  http://zhadum.org.uk/
>Environment:
System: NetBSD lyssa.zhadum.org.uk 5.99.51 NetBSD 5.99.51 (LYSSA) #0: Sat May 
21 11:53:54 BST 2011 tron%lyssa.zhadum.org.uk@localhost:/src/sys/compile/LYSSA 
i386
Architecture: i386
Machine: i386
>Description:
"screen" gets stuck during detach under NetBSD/i386 current since a few days.
It is working fine with 2011-05-13 build and doesn't work with a
2011-05-19 build and newer. I've attached "gdb" to the hung "screen"
process at it produced the following stack trace:

(gdb) where
#0  0xbbab2657 in _sys___sigsuspend14 () from /usr/lib/libc.so.12
#1  0xbbadb252 in pause () from /usr/lib/libc.so.12
#2  0x0806bb13 in ?? ()
#3  0x0000000f in ?? ()
#4  0x0806adc0 in ?? ()
#5  0x00000000 in ?? ()

I've suspicion that the problem is related to this change:

http://mail-index.netbsd.org/source-changes/2011/05/18/msg022025.html

I could however not find a problem when I reviewed the change to
"src/sys/kern/sys_sig.c".

>How-To-Repeat:
screen
<CTRL> "a" + "d"

>Fix:
Not known.