Comment 2 for bug 1562817

StacktraceTop:
 pa_alsa_path_set_volume (p=<optimized out>, m=0x12f67b0, cm=cm@entry=0x12188ec, v=v@entry=0x7f3971cdfa50, deferred_volume=deferred_volume@entry=true, write_to_hw=write_to_hw@entry=true) at modules/alsa/alsa-mixer.c:1219
 source_write_volume_cb (s=0x1218870) at modules/alsa/alsa-source.c:1250
 source_set_port_cb (s=0x1218870, p=<optimized out>) at modules/alsa/alsa-source.c:1382
 pa_source_process_msg (object=object@entry=0x1218870, code=code@entry=18, userdata=userdata@entry=0x7ffe6cdfb400, offset=offset@entry=0, chunk=chunk@entry=0x0) at pulsecore/source.c:2226
 source_process_msg (o=0x1218870, code=18, data=0x7ffe6cdfb400, offset=0, chunk=0x0) at modules/alsa/alsa-source.c:1086