Is it safe to call scheduler_add from a thread different then main

[giovancris]

The documentation of scheduler_add method said that:

/* this function adds a task into the scheduler to execute and directly returns

• if the pipe is not full. Otherwise the task is run directly. Should only be
• called from main thread or within task handler.
  Input:
  • function to execute to process the task
  • userdata to call the execution function with
  • array size that will be divided over multible threads
    Output:
  • task handle used to wait for the task to finish or check if done. Needs
    to be persistent over the process of the task
    */

Is it not safe to call the scheduler_add method from the same thread where we call scheduler_start if this thread is different from the main thread?