comments

esphome/core/lwip_fast_select.c

@@ -128,6 +128,10 @@ static void esphome_socket_event_callback(struct netconn *conn, enum netconn_evt
 void esphome_lwip_fast_select_init(void) { s_main_loop_task = xTaskGetCurrentTaskHandle(); }
 
 bool esphome_lwip_socket_has_data(int fd) {
+  // lwip_socket_dbg_get_socket() is a direct array lookup without the refcount that
+  // get_socket()/done_socket() uses. This is safe because the caller owns the socket
+  // lifetime: both has_data() and socket close happen on the main loop thread, so
+  // the sockets[] entry cannot be freed while we read it.
   struct lwip_sock *sock = lwip_socket_dbg_get_socket(fd);
   if (sock == NULL || sock->conn == NULL)
     return false;

esphome/core/lwip_fast_select.h

@@ -14,8 +14,9 @@ extern "C" {
 void esphome_lwip_fast_select_init(void);
 
 /// Check if a LwIP socket has data ready via direct rcvevent read (~215 ns per socket).
-/// Uses lwip_socket_dbg_get_socket() which is a direct array lookup — no locking, no refcount.
-/// Safe for single-threaded polling from the main loop.
+/// Uses lwip_socket_dbg_get_socket() — a direct array lookup without the refcount that
+/// get_socket()/done_socket() uses. Safe because the caller owns the socket lifetime:
+/// both has_data reads and socket close/unregister happen on the main loop thread.
 bool esphome_lwip_socket_has_data(int fd);
 
 /// Hook a socket's netconn callback to notify the main loop task on receive events.