Here's a test case: [poll_test.c](/uploads/ccf69b7248a07ab4de43b17a6612cebd/poll_test.c)
Run the exe with Wine, run `nc 127.0.0.1 12345`, attach to the Wine process with gdb, press Enter in the terminal running the `nc` command. You should see wineserver start to use 100% of a CPU core.