gstvideodecoder.c: excessive locking triggering many deadlocks
Submitted by min..@..arp.fm
Link to original bug (#783627)
Description
gst_video_decoder_negotiate() is triggering a deadlock during playback:
GST_VIDEO_DECODER_STREAM_LOCK (decoder);
gst_pad_check_reconfigure (decoder->srcpad);
if (klass->negotiate) {
ret = klass->negotiate (decoder); // deadlock here
if (!ret)
gst_pad_mark_reconfigure (decoder->srcpad);
}
GST_VIDEO_DECODER_STREAM_UNLOCK (decoder);
After locking the element, we get stop waiting for a condition to be completed inside klass->negotiate() as follows:
Thread 21 (Thread 0x6a1ff460 (LWP 28443)):
#0 syscall () at ../ports/sysdeps/unix/sysv/linux/arm/syscall.S:37
#1 0x76d7943c in g_cond_wait (cond=0x6de57c54, mutex=0x6de57c04) at /build/glib2.0-tTvduh/glib2.0-2.42.1/./glib/gthread-posix.c:1396
#2 0x76f052c4 in do_probe_callbacks (pad=0x6de57bf8, info=0x6a1fea78, defaultval=GST_FLOW_OK) at gstpad.c:3666
#3 0x76f07104 in gst_pad_peer_query (pad=0x6de57bf8, query=0x7190ca00) at gstpad.c:4071
#4 0x76330cc4 in gst_video_decoder_negotiate_pool (decoder=0x71836150, caps=0x72204ea0) at gstvideodecoder.c:3708
#5 0x763315c8 in gst_video_decoder_negotiate_default (decoder=0x71836150) at gstvideodecoder.c:3859
#6 0x763317ac in gst_video_decoder_negotiate (decoder=0x71836150) at gstvideodecoder.c:3900
#7 0x72e6c28c in gst_omx_video_dec_reconfigure_output_port (self=0x71836150) at gstomxvideodec.c:974
#8 0x72e6d530 in gst_omx_video_dec_loop (self=0x71836150) at gstomxvideodec.c:1289
#9 0x76f519e8 in gst_task_func (task=0x6de4c2c8) at gsttask.c:332
#10 0x76f5305c in default_func (tdata=0x1ca9a0, pool=0x38c58) at gsttaskpool.c:69
#11 0x76d5945c in g_thread_pool_thread_proxy (data=<optimized out>) at /build/glib2.0-tTvduh/glib2.0-2.42.1/./glib/gthreadpool.c:307
#12 0x76d588c4 in g_thread_proxy (data=0x718032f0) at /build/glib2.0-tTvduh/glib2.0-2.42.1/./glib/gthread.c:764
#13 0x76c9ae90 in start_thread (arg=0x6a1ff460) at pthread_create.c:311
#14 0x76c24598 in ?? () at ../ports/sysdeps/unix/sysv/linux/arm/nptl/../clone.S:92 from /lib/arm-linux-gnueabihf/libc.so.6 In another thread, playback is going on, which then tries to lock the same element, in the process, deadlock:
Thread 17 (Thread 0x6c5ff460 (LWP 28437)):
#0 0x76ca2780 in __lll_lock_wait (futex=futex@entry=0x71801688, private=<optimized out>) at ../ports/sysdeps/unix/sysv/linux/arm/nptl/lowlevellock.c:46
#1 0x76c9d3c4 in __GI___pthread_mutex_lock (mutex=0x71801688) at pthread_mutex_lock.c:114
#2 0x76329b20 in gst_video_decoder_chain (pad=0x6de57aa8, parent=0x71836150, buf=0x75643970) at gstvideodecoder.c:2430
#3 0x76f07bd0 in gst_pad_chain_data_unchecked (pad=0x6de57aa8, type=4112, data=0x75643970) at gstpad.c:4205
#4 0x76f08bfc in gst_pad_push_data (pad=0x6de45958, type=4112, data=0x75643970) at gstpad.c:4457
#5 0x76f094c0 in gst_pad_push (pad=0x6de45958, buffer=0x75643970) at gstpad.c:4576
#6 0x767c4128 in gst_base_transform_chain (pad=0x6de45808, parent=0x2d5bb0, buffer=0x75643970) at gstbasetransform.c:2312
#7 0x76f07bd0 in gst_pad_chain_data_unchecked (pad=0x6de45808, type=4112, data=0x75643970) at gstpad.c:4205
#8 0x76f08bfc in gst_pad_push_data (pad=0x6de456b8, type=4112, data=0x75643970) at gstpad.c:4457
#9 0x76f094c0 in gst_pad_push (pad=0x6de456b8, buffer=0x75643970) at gstpad.c:4576
#10 0x7678ef1c in gst_base_parse_push_frame (parse=0x6de4a730, frame=0x71803b68) at gstbaseparse.c:2520
#11 0x7678dd08 in gst_base_parse_handle_and_push_frame (parse=0x6de4a730, frame=0x71803b68) at gstbaseparse.c:2337
#12 0x7678f850 in gst_base_parse_finish_frame (parse=0x6de4a730, frame=0x71803b68, size=43130) at gstbaseparse.c:2678
#13 0x72ec2188 in gst_h264_parse_handle_frame (parse=0x6de4a730, frame=0x71803b68, skipsize=0x6c5fea6c) at gsth264parse.c:1275
#14 0x7678cee0 in gst_base_parse_handle_buffer (parse=0x6de4a730, buffer=0x756b3a00, skip=0x6c5fea6c, flushed=0x6c5fea68) at gstbaseparse.c:2145
#15 0x767923d4 in gst_base_parse_chain (pad=0x6de45568, parent=0x6de4a730, buffer=0x75692cb8) at gstbaseparse.c:3227
#16 0x76f07bd0 in gst_pad_chain_data_unchecked (pad=0x6de45568, type=4112, data=0x75692cb8) at gstpad.c:4205
#17 0x76f08bfc in gst_pad_push_data (pad=0x6de45418, type=4112, data=0x75692cb8) at gstpad.c:4457
#18 0x76f094c0 in gst_pad_push (pad=0x6de45418, buffer=0x75692cb8) at gstpad.c:4576
#19 0x75fdcf78 in gst_single_queue_push_one (mq=0x6de452a8, sq=0x6de48cc8, object=0x75692cb8, allow_drop=0x6c5fed44) at gstmultiqueue.c:1608
#20 0x75fdede8 in gst_multi_queue_loop (pad=0x6de45418) at gstmultiqueue.c:1920
#21 0x76f519e8 in gst_task_func (task=0x7561e418) at gsttask.c:332
#22 0x76f5305c in default_func (tdata=0x1affe0, pool=0x38c58) at gsttaskpool.c:69
#23 0x76d5945c in g_thread_pool_thread_proxy (data=<optimized out>) at /build/glib2.0-tTvduh/glib2.0-2.42.1/./glib/gthreadpool.c:307
#24 0x76d588c4 in g_thread_proxy (data=0x75602000) at /build/glib2.0-tTvduh/glib2.0-2.42.1/./glib/gthread.c:764
#25 0x76c9ae90 in start_thread (arg=0x6c5ff460) at pthread_create.c:311
#26 0x76c24598 in ?? () at ../ports/sysdeps/unix/sysv/linux/arm/nptl/../clone.S:92 from /lib/arm-linux-gnueabihf/libc.so.6