examples/zcrx: handle CQ overflow

The request can get terminated if the CQ becomes full, handle it by
reissuing the request.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>

Author: isilence

examples/zcrx.c

@@ -353,6 +353,19 @@ static void return_buffer(struct io_uring_zcrx_rq *rq_ring,
 static void process_recvzc_error(struct io_uring *ring, struct zc_conn *conn,
 				 int ret)
 {
+	if (ret == -ENOSPC) {
+		size_t left = 0;
+
+		if (cfg_size) {
+			left = cfg_size - received;
+			if (left == 0)
+				t_error(1, 0, "ENOSPC for a finished request");
+		}
+
+		add_recvzc(ring, connfd, left);
+		return;
+	}
+
 	if (ret != 0)
 		t_error(1, 0, "invalid final recvzc ret %i", ret);
 	if (cfg_size && conn->received != cfg_size)