PA_LLIST_HEAD(pa_source_volume_change, volume_changes);
pa_source_volume_change *volume_changes_tail;
/* This value is updated in pa_source_volume_change_apply() and
PA_LLIST_HEAD(pa_source_volume_change, volume_changes);
pa_source_volume_change *volume_changes_tail;
/* This value is updated in pa_source_volume_change_apply() and