eth_device_init is not re-entrance, add a warning.

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@1479 bbd45198-f89e-11dd-88c7-29a3b14d5316

components/net/lwip-1.4.0/src/netif/ethernetif.c

@@ -153,6 +153,9 @@ static err_t ethernetif_init(struct netif *netif)
 
 
 /* ethernetif APIs */
+/* WARNING: because netif_set_up() is not re-entrance ( it will pending on sem/mbox )
+ * you MUST NOT call it before scheduler starts.
+ */
 rt_err_t eth_device_init(struct eth_device* dev, const char* name)
 {
 	struct netif* pnetif;