Timer task may stall if timer callback routine invokes blocking kernel service

To protect the global ressources of the timer module, the scheduler is locked while processing the registered timer callbacks. Functions which have the potential to block the current task (e.g. rX_SigWaitForSignal, rX_QueWaitForPacket) must not be called inside a timer callback routine as context switching is not allowed while scheduler is locked. This behaviour is not covered in the current documentation!

Suggestions:

• Change documentation and stay with the current implementation
• Introduce mutex to protect the global timer ressources and keep the current documentation