diff --git a/Project/Src/tinyUSB/examples/device/net_lwip_webserver/src/main.c b/Project/Src/tinyUSB/examples/device/net_lwip_webserver/src/main.c
index 9d5a798..5c24030 100644
--- a/Project/Src/tinyUSB/examples/device/net_lwip_webserver/src/main.c
+++ b/Project/Src/tinyUSB/examples/device/net_lwip_webserver/src/main.c
@@ -108,16 +108,16 @@ static const dhcp_config_t dhcp_config = {
 
 
 
-static void tud_output_fn(void *t){
+static int tud_output_fn(void *t){
   struct pbuf *p = t;
-  rt_kprintf("arrive %s:%d\n", __FILE__, __LINE__);
+  // rt_kprintf("arrive %s:%d\n", __FILE__, __LINE__);
   /* if the network driver can accept another packet, we make it happen */
   if (tud_network_can_xmit(p->tot_len)) {
     tud_network_xmit(p, 0 /* unused for this example */);
-    rt_kprintf("send %d bytes\n", p->tot_len);
-    // return ERR_OK;
+    // rt_kprintf("send %d bytes\n", p->tot_len);
+    return ERR_OK;
   }
-  // return ERR_USE;
+  return ERR_USE;
 }
 
 
@@ -130,14 +130,9 @@ static err_t linkoutput_fn(struct netif *netif, struct pbuf *p) {
     /* if TinyUSB isn't ready, we must signal back to lwip that there is nothing we can do */
     if (!tud_ready())
       return ERR_USE;
-    /*rc  this packet will be sent in usbd task */
-    rt_kprintf("arrive %s:%d\n", __FILE__, __LINE__);
-    usbd_defer_func(tud_output_fn, p, false);
-    return ERR_OK;
-    // return usbd_defer_func_wait(tud_output_fn, p);
-    /* transfer execution to TinyUSB in the hopes that it will finish transmitting the prior packet */
-    /*rc: if use rtos, this function still will be called? */
-    // tud_task();
+    // rt_kprintf("arrive %s:%d\n", __FILE__, __LINE__);
+    // 这里要等待usb线程处理完成，因为这个函数返回之后，lwip会释放p
+    return usbd_defer_func_wait(tud_output_fn, p);
   }
 }
 
@@ -228,10 +223,7 @@ bool tud_network_recv_cb(const uint8_t *src, uint16_t size) {
     /* Copy buf to pbuf */
     pbuf_take(p, src, size);
 
-    // Surrender ownership of our pbuf unless there was an error
-    // Only call pbuf_free if not Ok else it will panic with "pbuf_free: p->ref > 0"
-    // or steal it from whatever took ownership of it with undefined consequences.
-    // See: https://savannah.nongnu.org/patch/index.php?10121
+    // 把数据交给lwip处理，由于usb线程优先级比tcpip线程优先级低，所以这里会天然等待lwip处理完成
     if (err=netif->input(p, netif),err != ERR_OK) {
       rt_kprintf("ERROR: netif input failed, err=%d\n", err);
       pbuf_free(p);
@@ -358,9 +350,9 @@ int init_tinyusb(void) {
   while (dhserv_init(&dhcp_config) != ERR_OK){
     rt_thread_mdelay(10);
   }
-  // while (dnserv_init(IP_ADDR_ANY, 53, dns_query_proc) != ERR_OK){
-  //   rt_thread_mdelay(10);
-  // }
+  while (dnserv_init(IP_ADDR_ANY, 53, dns_query_proc) != ERR_OK){
+    rt_thread_mdelay(10);
+  }
   httpd_init();
 
 #ifdef INCLUDE_IPERF
@@ -393,26 +385,8 @@ int init_tinyusb(void) {
     }
 
     rt_thread_startup(tid);
-  // while (1) {
-  //   tud_task();
-  //   // sys_check_timeouts(); // service lwip
-  //   // handle_link_state_switch();
-  // }
 
   return 0;
 }
 extern_init(tinyusb, init_tinyusb);
 
-/* lwip has provision for using a mutex, when applicable */
-/* This implementation is for single-threaded use only */
-// sys_prot_t sys_arch_protect(void) {
-//   return 0;
-// }
-// void sys_arch_unprotect(sys_prot_t pval) {
-//   (void) pval;
-// }
-
-// /* lwip needs a millisecond time source, and the TinyUSB board support code has one available */
-// uint32_t sys_now(void) {
-//   return board_millis();
-// }
diff --git a/Project/Src/tinyUSB/lib/networking/dnserver.c b/Project/Src/tinyUSB/lib/networking/dnserver.c
index fd521b7..bbb7313 100644
--- a/Project/Src/tinyUSB/lib/networking/dnserver.c
+++ b/Project/Src/tinyUSB/lib/networking/dnserver.c
@@ -139,7 +139,7 @@ static void udp_recv_proc(void *arg, struct udp_pcb *upcb, struct pbuf *p, const
 	ip4_addr_t host_addr;
 	dns_answer_t *answer;
 
-  rt_kprintf("DNS query\n");
+  // rt_kprintf("DNS query\n");
   (void)arg;
 
 	if (p->len <= sizeof(dns_header_t)) goto error;