[Qemu-devel] Re: [PATCH 3/5] char: Add framework for a 'write unblocked' callback

[Gerd Hoffmann]

  Hi,

@@ -60,6 +60,9 @@ struct CharDriverState {
      IOEventHandler *chr_event;
      IOCanReadHandler *chr_can_read;
      IOReadHandler *chr_read;
+    IOHandler *chr_write_unblocked;
+    void (*update_fd_handlers)(struct CharDriverState *chr,
+                               bool poll_out);

I think you don't need that callback in the first place if you are able 
to just enable/disable the handlers for a file handle.

cheers,
  Gerd