Re: Kaffeine problem with CFS

Ingo Molnar
2007-04-18T10:50:05Z

* Ingo Molnar <mingo@elte.hu> wrote:

> > hm. I've reviewed all uses of demux_lock. ./src/xine-engine/demux.c
> > does this:
>
> plus it does this too:
>
> pthread_mutex_unlock( &stream->demux_lock );
> xine_usec_sleep(100000);
> pthread_mutex_lock( &stream->demux_lock );
>
> this would explain the nanosleep() strace entries. But the task stuck
> on demux_lock never gets the unlock event. Weird.

9303 is stuck here on demux_lock:

#0 0xffffe410 in __kernel_vsyscall ()
#1 0x4a2538ce in __lll_mutex_lock_wait () from /lib/libpthread.so.0
#2 0x4a24f71c in _L_mutex_lock_79 () from /lib/libpthread.so.0
#3 0x4a24f24d in pthread_mutex_lock () from /lib/libpthread.so.0
#4 0xb79f64f9 in xine_play () from /usr/lib/libxine.so.1

that mutex related futex is at address 0xb07409e0, but the only sign in
the strace of that futex being touched is:

9303 futex(0xb07409e0, FUTEX_WAIT, 2, NULL <unfinished ...>

no other event ever happens on futex 0xb07409e0. Other threads dont
touch it.

Maybe thread 9324 is the owner of that mutex, and it's looping somewhere
that does xine_xmalloc_aligned(), with the lock held? It did this:

#0 0xffffe410 in __kernel_vsyscall ()
#1 0x4a2539e1 in __lll_mutex_unlock_wake () from /lib/libpthread.so.0
#2 0x4a2506f9 in _L_mutex_unlock_99 () from /lib/libpthread.so.0
#3 0x4a250370 in __pthread_mutex_unlock_usercnt () from /lib/libpthread.so.0
#4 0x4a2506f0 in pthread_mutex_unlock () from /lib/libpthread.so.0
#5 0xb79fce5a in QWidget::setUpdatesEnabled () from /usr/lib/libxine.so.1
#6 0xb7a4b90b in dvd_plugin_free_buffer (buf=0xb0745470) at input_dvd.c:570
#7 0xb7a030a2 in QWidget::setUpdatesEnabled () from /usr/lib/libxine.so.1
#8 0x4a24d2db in start_thread () from /lib/libpthread.so.0
#9 0x4a05820e in clone () from /lib/libc.so.6

Ingo