ngx_queue_prev     64 src/core/ngx_queue.c         prev = ngx_queue_prev(q);
ngx_queue_prev     74 src/core/ngx_queue.c             prev = ngx_queue_prev(prev);
ngx_queue_prev   1696 src/http/ngx_http_file_cache.c          q = ngx_queue_prev(q))
ngx_queue_prev    978 src/http/ngx_http_spdy_filter_module.c          q = ngx_queue_prev(q))