jackd2 hangs when stopping

[mokabar]

using jackd2 on 12.04, the the jackdbus process hangs when trying to stop jack via qjackctl. unfortunately there is no debug package for jackd/libjack, so the backtrace is not really helpful:

(gdb) thread apply all bt

Thread 4 (Thread 0x7f6be01b8700 (LWP 17410)):
#0 sem_wait () at ../nptl/sysdeps/unix/sysv/linux/x86_64/sem_wait.S:86
#1 0x00007f6be42b1ce8 in ?? ()
#2 0x00007f6be01b8700 in ?? ()
#3 0x0000000000000000 in ?? ()

Thread 3 (Thread 0x7f6bdf7b6700 (LWP 17411)):
#0 sem_wait () at ../nptl/sysdeps/unix/sysv/linux/x86_64/sem_wait.S:86
#1 0x00007f6be42b1ce8 in ?? ()
#2 0x0000000000000000 in ?? ()

Thread 2 (Thread 0x7f6bdedb4700 (LWP 17412)):
#0 sem_wait () at ../nptl/sysdeps/unix/sysv/linux/x86_64/sem_wait.S:86
#1 0x00007f6be42b1ce8 in ?? ()
#2 0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7f6be63c5740 (LWP 17409)):
#0 0x00007f6be50e5b03 in __GI___poll (fds=<optimized out>, nfds=<optimized out>, timeout=<optimized out>)
    at ../sysdeps/unix/sysv/linux/poll.c:87
#1 0x00007f6be5609de0 in ?? () from /lib/x86_64-linux-gnu/libdbus-1.so.3
#2 0x00007f6be5608ccd in ?? () from /lib/x86_64-linux-gnu/libdbus-1.so.3
#3 0x00007f6be55f3c05 in ?? () from /lib/x86_64-linux-gnu/libdbus-1.so.3
#4 0x00007f6be55f4ca2 in ?? () from /lib/x86_64-linux-gnu/libdbus-1.so.3
#5 0x000000000040463c in ?? ()
#6 0x00007f6be502076d in __libc_start_main (main=0x404380, argc=2, ubp_av=0x7fff0b2ab3e8, init=<optimized out>, fini=<optimized out>,
    rtld_fini=<optimized out>, stack_end=0x7fff0b2ab3d8) at libc-start.c:226
#7 0x0000000000404995 in ?? ()
#8 0x00007fff0b2ab3d8 in ?? ()
#9 0x000000000000001c in ?? ()
#10 0x0000000000000002 in ?? ()
#11 0x00007fff0b2acbd0 in ?? ()
#12 0x00007fff0b2acbe2 in ?? ()
#13 0x0000000000000000 in ?? ()

the backtrace via totalview is a bit more helpful:

> 0 __poll PC=0x7f6be50e5b03, FP=0x7fff0b2ab0d0 [/usr/lib/debug/lib/x86_64-linux-gnu/libc-2.15.so]
   1 dbus_threads_init_default PC=0x7f6be5609ddb, FP=0x7fff0b2ab110 [/lib/x86_64-linux-gnu/libdbus-1.so.3]
   2 dbus_threads_init_default PC=0x7f6be5608cca, FP=0x7fff0b2ab130 [/lib/x86_64-linux-gnu/libdbus-1.so.3]
   3 dbus_connection_open PC=0x7f6be55f3c00, FP=0x7fff0b2ab160 [/lib/x86_64-linux-gnu/libdbus-1.so.3]
   4 dbus_connection_dispatch PC=0x7f6be55f4c9d, FP=0x7fff0b2ab180 [/lib/x86_64-linux-gnu/libdbus-1.so.3]
   5 Unknown PC=0x00404637, FP=0x7fff0b2ab300 [/usr/bin/jackdbus]
   6 __libc_start_main PC=0x7f6be5020769, FP=0x7fff0b2ab3c0 [/usr/lib/debug/lib/x86_64-linux-gnu/libc-2.15.so]
   7 Unknown PC=0x00404990, FP=0x7fff0b2ab3d0 [/usr/bin/jackdbus]

[mokabar (tim-klingt)]

updating qjackctl to 0.3.9 seems to solve the issue