Bug 90135

While reviewing the test case for https://bugs.freedesktop.org/show_bug.cgi?id=89297 a thread blocking issue has been detected with a slighty modified test case, which is appended to this bug.

The test case sends messages to the session bus over a dbus connection from two threads, which works fine in mostly cases (visible by the test case output).

From time to time the output stops for about 40-60 seconds and then continues. On that case the threads shows the following back trace. 

Program received signal SIGINT, Interrupt.
0x00007ffff761f20d in nanosleep () from /lib64/libc.so.6
(gdb) info thread
  Id   Target Id         Frame 
  3    Thread 0x7ffff6b5d700 (LWP 1779) "dbus-test" 0x00007ffff79210af in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  2    Thread 0x7ffff735e700 (LWP 1778) "dbus-test" 0x00007ffff76457bd in poll () from /lib64/libc.so.6
* 1    Thread 0x7ffff7fbe700 (LWP 1774) "dbus-test" 0x00007ffff761f20d in nanosleep () from /lib64/libc.so.6
(gdb) thread 3
[Switching to thread 3 (Thread 0x7ffff6b5d700 (LWP 1779))]
#0  0x00007ffff79210af in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
(gdb) bt
#0  0x00007ffff79210af in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x00007ffff7bb1bea in _dbus_platform_condvar_wait () from /home/xxx/dbus/usr/local/lib/libdbus-1.so.3
#2  0x00007ffff7b8be59 in _dbus_condvar_wait () from /home/xxx/dbus/usr/local/lib/libdbus-1.so.3
#3  0x00007ffff7b55987 in _dbus_connection_acquire_io_path () from /home/xxx/dbus/usr/local/lib/libdbus-1.so.3
#4  0x00007ffff7b55cbb in _dbus_connection_do_iteration_unlocked () from /home/xxx/dbus/usr/local/lib/libdbus-1.so.3
#5  0x00007ffff7b5ab46 in _dbus_connection_flush_unlocked () from /home/xxx/dbus/usr/local/lib/libdbus-1.so.3
#6  0x00007ffff7b58165 in _dbus_connection_block_pending_call () from /home/xxx/dbus/usr/local/lib/libdbus-1.so.3
#7  0x00007ffff7b821d4 in dbus_pending_call_block () from /home/xxx/dbus/usr/local/lib/libdbus-1.so.3
#8  0x00007ffff7b5aa13 in dbus_connection_send_with_reply_and_block () from /home/xxx/dbus/usr/local/lib/libdbus-1.so.3
#9  0x0000000000400ea4 in fun ()
#10 0x00007ffff791d0db in start_thread () from /lib64/libpthread.so.0
#11 0x00007ffff764e58d in clone () from /lib64/libc.so.6
(gdb) thread 2
[Switching to thread 2 (Thread 0x7ffff735e700 (LWP 1778))]
#0  0x00007ffff76457bd in poll () from /lib64/libc.so.6
(gdb) bt
#0  0x00007ffff76457bd in poll () from /lib64/libc.so.6
#1  0x00007ffff7baf660 in _dbus_poll () from /home/xxx/dbus/usr/local/lib/libdbus-1.so.3
#2  0x00007ffff7b907a0 in socket_do_iteration () from /home/xxx/dbus/usr/local/lib/libdbus-1.so.3
#3  0x00007ffff7b8da64 in _dbus_transport_do_iteration () from /home/xxx/dbus/usr/local/lib/libdbus-1.so.3
#4  0x00007ffff7b55d9c in _dbus_connection_do_iteration_unlocked () from /home/xxx/dbus/usr/local/lib/libdbus-1.so.3
#5  0x00007ffff7b5855f in _dbus_connection_block_pending_call () from /home/xxx/dbus/usr/local/lib/libdbus-1.so.3
#6  0x00007ffff7b821d4 in dbus_pending_call_block () from /home/xxx/dbus/usr/local/lib/libdbus-1.so.3
#7  0x00007ffff7b5aa13 in dbus_connection_send_with_reply_and_block () from /home/xxx/dbus/usr/local/lib/libdbus-1.so.3
#8  0x0000000000400ea4 in fun ()
#9  0x00007ffff791d0db in start_thread () from /lib64/libpthread.so.0
#10 0x00007ffff764e58d in clone () from /lib64/libc.so.6
(gdb) c
Continuing.