BUG/MEDIUM: h1: Make sure we subscribe before going into idle list.

In h1_detach(), make sure we subscribe before we call
srv_add_to_idle_list(), not after. As soon as srv_add_to_idle_list() is
called, and it is put in an idle list, another thread can take it, and
we're no longer allowed to subscribe.
This fixes a race condition when another thread grabs a connection as soon
as it is put, the original owner would subscribe, and thus the new thread
would fail to do so, and to activate polling.

diff --git a/src/mux_h1.c b/src/mux_h1.c
index f4cf0ff84c4f64426a55a3fead227ed9753e019d..fee645b191a3459361c2b2fc485c9dae3a55cc29 100644 (file)
--- a/src/mux_h1.c
+++ b/src/mux_h1.c
@@ -2466,13 +2466,13 @@ static void h1_detach(struct conn_stream *cs)
                if (!(h1c->conn->flags & CO_FL_PRIVATE)) {
                        if (h1c->conn->owner == sess)
                                h1c->conn->owner = NULL;
+                       h1c->conn->xprt->subscribe(h1c->conn, h1c->conn->xprt_ctx, SUB_RETRY_RECV, &h1c->wait_event);
                        if (!srv_add_to_idle_list(objt_server(h1c->conn->target), h1c->conn, is_not_first)) {
                                /* The server doesn't want it, let's kill the connection right away */
                                h1c->conn->mux->destroy(h1c);
                                TRACE_DEVEL("outgoing connection killed", H1_EV_STRM_END|H1_EV_H1C_END);
                                goto end;
                        }
-                       h1c->conn->xprt->subscribe(h1c->conn, h1c->conn->xprt_ctx, SUB_RETRY_RECV, &h1c->wait_event);
                        return;
                }
        }