[Xenomai] Queue corruption from XDDP in Xenomai 2.6.1

[Doug Brunner <dbrunner@ebus.com>]

It looks like the bug I wrote about back in June still exists in Xenomai 
2.6.1 (with Linux 3.2.21). I ran the same test case (an RT thread opens 
an XDDP socket, then a Linux thread opens its end of the pipe, then the 
RT thread stops, then with the Linux thread still holding its end of the 
pipe another RT thread tries to open an XDDP socket with the same minor 
number). With Xenomai queue and I-pipe debugging enabled, I got a report 
of a corrupted queue. I've attached my config, test case, and serial 
console log.

So far I haven't found anything in the XDDP or underlying xnpipe_* code 
that would suggest why this is happening. However something is 
definitely going wrong, since xnpipe_minor_free should not be called 
until my Linux task closes its end of the pipe, so the call by the 
second RT thread to open the pipe should fail with -EBUSY. Any thoughts 
on why this might be happening?

-- 
     Doug Brunner

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Loading Linux 3.2.21-ipipe-small-2-ipd ...

?EXT4-fs (hda1): couldn't mount as ext3 due to feature incompatibilities
EXT4-fs (hda1): couldn't mount as ext2 due to feature incompatibilities

INIT: version 2.88 booting

Using makefile-style concurrent boot in runlevel S.
Starting the hotplug events dispatcher: udevd.
Synthesizing the initial hotplug events...done.
Waiting for /dev to be fully populated...done.
Setting preliminary keymap...done.
Activating swap...done.
Checking root file system...fsck from util-linux-ng 2.17.2
/dev/hda1: clean, 72970/256512 files, 579050/1026048 blocks
done.
Cleaning up ifupdown....
Setting up networking....
Loading kernel modules...done.
Activating lvm and md swap...done.
Checking file systems...fsck from util-linux-ng 2.17.2
done.
Mounting local filesystems...done.
Activating swapfile swap...done.
Cleaning up temporary files....
Configuring network interfaces...done.
Starting portmap daemon....
Starting NFS common utilities: statd.
Cleaning up temporary files....
Setting console screen modes.
^[]Rcannot (un)set powersave mode
^[[9;30]^[[14;30]Skipping font and keymap setup (handled by console-setup).
Setting up console font and keymap...done.
Setting sensors limits.
Setting kernel variables ...done.
Loading the saved-state of the serial devices... 
/dev/ttyS0 at 0x03f8 (irq = 4) is a 16550A

INIT: Entering runlevel: 2

Using makefile-style concurrent boot in runlevel 2.
Enabling additional executable binary formats: binfmt-supportmount: mount point /proc/sys/fs/binfmt_misc does not exist
Starting NFS common utilities: statd.
Starting portmap daemon...Already running..
Starting enhanced syslogd: rsyslogd.
Starting anac(h)ronistic cron: anacron.
Starting deferred execution scheduler: atd.
Starting periodic command scheduler: cron.
Starting system message bus: dbus.
Starting Avahi mDNS/DNS-SD Daemon: avahi-daemon.
Starting MTA:Starting kerneloops:
 exim4.
Loading cpufreq kernel modules...done (none).
CPUFreq Utilities: Setting ondemand CPUFreq governor...disabled, governor not available...done.
Starting network connection manager: NetworkManager.
Starting OpenBSD Secure Shell server: sshd.
I-pipe: Detected stalled head domain, probably caused by a bug.
        A critical section may have been left unterminated.

Debian GNU/Linux 6.0 eve-0000 ttyS0

eve-0000 login: root
Password: 
Last login: Wed Sep  5 10:53:59 PDT 2012 on ttyS0
Linux eve-0000 3.2.21-ipipe-small-2-ipd #7 Wed Sep 5 17:45:26 UTC 2012 i586

The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
root@eve-0000:~# ./xddp-trycrash
Xenomai: corrupted queue, qslot->elems=5/5, qslot=b065b9c0 at kernel/xenomai/nucleus/heap.c:332

 CPU  PID    PRI      TIMEOUT  STAT      NAME
>  0  0       -1      0        00500080  ROOT
   0  1539     0      0        00b00380  xddp-trycrash
   0  1542     0      0        00b00380  xddp-trycrash
   0  1543    42      0        00300380  xddp-trycrash
Master time base: clock=100421966997