port-powerpc/44387: some pthread mutex tests fail on ppc platforms

[riz%NetBSD.org@localhost]

>Number:         44387
>Category:       port-powerpc
>Synopsis:       some pthread mutex tests fail on ppc platforms
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    port-powerpc-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Jan 14 16:50:00 +0000 2011
>Originator:     Jeff Rizzo
>Release:        5.99.43
>Organization:
>Environment:
NetBSD powerbookg4 5.99.43 NetBSD 5.99.43 (GENERIC) #1: Fri Jan 14 08:25:34 PST 
2011  
riz%hack.lan@localhost:/Users/riz/Documents/code/netbsd/obj/sys/arch/macppc/compile/GENERIC
 macppc

>Description:
Using a kernel that is *not* build with "options DIAGNOSTIC", the regression 
tests in
/usr/tests/lib/libpthread/t_mutex fail on various powerpc platforms.  The 
failing test basically creates two threads which each increment a variable 
which is protected by a mutex;  when it fails (it doesn't fail 100% of the 
time), it looks like both threads are in "parked" state.  (I have also seen one 
thread parked and one in iowait)

I confirmed this on two different macppc boxes I have, and I have at least one 
test run from an ofppc box running 5.99.42 (without DIAGNOSTIC).

For whatever reason, building the kernel with DIAGNOSTIC seems to hide the 
problem.  I have not yet determined why;  no additional output is available.

In case it matters:  one machine has a PPC 7400, one has a 7447, and one has a 
750CX CPU.
>How-To-Repeat:
On a machine with a GENERIC kernel:

cd /usr/tests/lib/libpthread
powerbookg4:riz  /usr/tests/lib/libpthread> ./t_mutex mutex2
1: Mutex-test 2
1: Thread 0xffe00000
2: Second thread (0xefa00000). Count is 10000000

<hang indefinitely>

Sometimes it does not hang - frequency of hang seems to vary by machine and 
kernel.  You may also wish to run the entire pthread test suite from that 
directory with "atf-run | atf-report".  It will take about 10 minutes (because 
of the mutex test hangs).  
>Fix:
None given.