nginx 0.8.53 *) Feature: now the "error_page" directive allows to change a status code in a redirect. *) Feature: the "gzip_disable" directive supports special "degradation" mask. *) Bugfix: a socket leak might occurred if file AIO was used. Thanks to Maxim Dounin. *) Bugfix: if the first server had no "listen" directive and there was no explicit default server, then a next server with a "listen" directive became the default server; the bug had appeared in 0.8.21.

--- a/src/core/ngx_output_chain.c
+++ b/src/core/ngx_output_chain.c
@@ -74,18 +74,18 @@ ngx_output_chain(ngx_output_chain_ctx_t 
         }
     }
 
-#if (NGX_HAVE_FILE_AIO)
-    if (ctx->aio) {
-        return NGX_AGAIN;
-    }
-#endif
-
     out = NULL;
     last_out = &out;
     last = NGX_NONE;
 
     for ( ;; ) {
 
+#if (NGX_HAVE_FILE_AIO)
+        if (ctx->aio) {
+            return NGX_AGAIN;
+        }
+#endif
+
         while (ctx->in) {
 
             /*