RnaSessStop

This function is called when Dial-Up Networking wants to terminate the SMM. The overlaying SMM should do the following during this function.

• If the overlaying SMM has not handed off the control to the overlaid SMM (by calling its Start function) when this function is called, it means the overlaying SMM is managing the session in a separate thread. The overlaying SMM must stop managing the session as soon as possible. When it can stop the task it needs to call the RnaTerminate function.
• If the overlaying SMM already calls the overlaid SMM's Start function, it can simply call the overlaid SMM's Stop function and return immediately.

In the sample, SMMSessStop determines whether it has started managing the session by the existence of the session control block for the connection. If the session control block does not exist, it never manages the session, so it can bypass the Stop function to the PPPSMM immediately. Otherwise, it signals an event the session management thread to stops managing the session. When the thread detects the event, it terminates the session and calls RnaComplete or simply calls the PPPSMM to stop the session.