nginx-1.12.1.patch

diff --git a/src/core/ngx_core.h b/src/core/ngx_core.h
index 2069373b..e24e5df5 100644
--- a/src/core/ngx_core.h
+++ b/src/core/ngx_core.h
@@ -39,6 +39,7 @@ typedef void (*ngx_connection_handler_pt)(ngx_connection_t *c);
 #define  NGX_DONE       -4
 #define  NGX_DECLINED   -5
 #define  NGX_ABORT      -6
+#define  NGX_BLOCK      -7
 
 
 #include <ngx_errno.h>
diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
index 36952860..a2fa6b34 100644
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -35,8 +35,6 @@ static void ngx_http_upstream_rd_check_broken_connection(ngx_http_request_t *r);
 static void ngx_http_upstream_wr_check_broken_connection(ngx_http_request_t *r);
 static void ngx_http_upstream_check_broken_connection(ngx_http_request_t *r,
     ngx_event_t *ev);
-static void ngx_http_upstream_connect(ngx_http_request_t *r,
-    ngx_http_upstream_t *u);
 static ngx_int_t ngx_http_upstream_reinit(ngx_http_request_t *r,
     ngx_http_upstream_t *u);
 static void ngx_http_upstream_send_request(ngx_http_request_t *r,
@@ -1457,36 +1455,42 @@ ngx_http_upstream_check_broken_connection(ngx_http_request_t *r,
 }
 
 
-static void
+void
 ngx_http_upstream_connect(ngx_http_request_t *r, ngx_http_upstream_t *u)
 {
     ngx_int_t          rc;
     ngx_connection_t  *c;
 
-    r->connection->log->action = "connecting to upstream";
+    if (!u->blocked) {
+        r->connection->log->action = "connecting to upstream";
 
-    if (u->state && u->state->response_time) {
-        u->state->response_time = ngx_current_msec - u->state->response_time;
-    }
+        if (u->state && u->state->response_time) {
+            u->state->response_time = ngx_current_msec - u->state->response_time;
+        }
 
-    u->state = ngx_array_push(r->upstream_states);
-    if (u->state == NULL) {
-        ngx_http_upstream_finalize_request(r, u,
-                                           NGX_HTTP_INTERNAL_SERVER_ERROR);
-        return;
-    }
+        u->state = ngx_array_push(r->upstream_states);
+        if (u->state == NULL) {
+            ngx_http_upstream_finalize_request(r, u,
+                                               NGX_HTTP_INTERNAL_SERVER_ERROR);
+            return;
+        }
 
-    ngx_memzero(u->state, sizeof(ngx_http_upstream_state_t));
+        ngx_memzero(u->state, sizeof(ngx_http_upstream_state_t));
 
-    u->state->response_time = ngx_current_msec;
-    u->state->connect_time = (ngx_msec_t) -1;
-    u->state->header_time = (ngx_msec_t) -1;
+        u->state->response_time = ngx_current_msec;
+        u->state->connect_time = (ngx_msec_t) -1;
+        u->state->header_time = (ngx_msec_t) -1;
+    }
 
     rc = ngx_event_connect_peer(&u->peer);
 
     ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                    "http upstream connect: %i", rc);
 
+    if (rc == NGX_BLOCK) {
+        return;
+    }
+
     if (rc == NGX_ERROR) {
         ngx_http_upstream_finalize_request(r, u,
                                            NGX_HTTP_INTERNAL_SERVER_ERROR);
diff --git a/src/http/ngx_http_upstream.h b/src/http/ngx_http_upstream.h
index c552ac0c..92bb6229 100644
--- a/src/http/ngx_http_upstream.h
+++ b/src/http/ngx_http_upstream.h
@@ -389,6 +389,7 @@ struct ngx_http_upstream_s {
     unsigned                         request_sent:1;
     unsigned                         request_body_sent:1;
     unsigned                         header_sent:1;
+    unsigned                         blocked:1;
 };
 
 
@@ -416,6 +417,8 @@ char *ngx_http_upstream_param_set_slot(ngx_conf_t *cf, ngx_command_t *cmd,
 ngx_int_t ngx_http_upstream_hide_headers_hash(ngx_conf_t *cf,
     ngx_http_upstream_conf_t *conf, ngx_http_upstream_conf_t *prev,
     ngx_str_t *default_hide_headers, ngx_hash_init_t *hash);
+void ngx_http_upstream_connect(ngx_http_request_t *r,
+    ngx_http_upstream_t *u);
 
 
 #define ngx_http_conf_upstream_srv_conf(uscf, module)                         \