diff --git a/include/proto/server.h b/include/proto/server.h
index b101b3e..ff4ec77 100644
--- a/include/proto/server.h
+++ b/include/proto/server.h
@@ -64,10 +64,9 @@
 /* increase the number of cumulated connections on the designated server */
 static void inline srv_inc_sess_ctr(struct server *s)
 {
-	s->counters.cum_sess++;
-	update_freq_ctr(&s->sess_per_sec, 1);
-	if (s->sess_per_sec.curr_ctr > s->counters.sps_max)
-		s->counters.sps_max = s->sess_per_sec.curr_ctr;
+	HA_ATOMIC_ADD(&s->counters.cum_sess, 1);
+	HA_ATOMIC_UPDATE_MAX(&s->counters.sps_max,
+			     update_freq_ctr(&s->sess_per_sec, 1));
 }
 
 /* set the time of last session on the designated server */
diff --git a/include/proto/stream.h b/include/proto/stream.h
index 00f452c..aae7d34 100644
--- a/include/proto/stream.h
+++ b/include/proto/stream.h
@@ -262,17 +262,23 @@
 
 static void inline stream_add_srv_conn(struct stream *sess, struct server *srv)
 {
+	SPIN_LOCK(SERVER_LOCK, &srv->lock);
 	sess->srv_conn = srv;
 	LIST_ADD(&srv->actconns, &sess->by_srv);
+	SPIN_UNLOCK(SERVER_LOCK, &srv->lock);
 }
 
 static void inline stream_del_srv_conn(struct stream *sess)
 {
-	if (!sess->srv_conn)
+	struct server *srv = sess->srv_conn;
+
+	if (!srv)
 		return;
 
+	SPIN_LOCK(SERVER_LOCK, &srv->lock);
 	sess->srv_conn = NULL;
 	LIST_DEL(&sess->by_srv);
+	SPIN_UNLOCK(SERVER_LOCK, &srv->lock);
 }
 
 static void inline stream_init_srv_conn(struct stream *sess)