The following pseudo code implements the suspend() and activate() functions. Two new states are introduced, suspended_ready and suspended_blocked, to keep track of the state in which a process was suspended. That is, a ready process moves to the suspended_ready state by the suspend function. Similarly, a blocked process moves to the suspended_blocked state by the suspend function. The activate function reverses the transitions. suspend() { if (p. process_state == blocked) p. process_state - suspended_blocked else p. process_state = suspended_ready } activate() { if (p. process_state == suspended_ready) p. process_state - ready else p. process_state - blocked scheduler() (a) What changes must be made to the scheduler or other functions to make suspend/activate work correctly?
(b) Why is the scheduler called only in activate but not in suspend?
(c) A process must be prevented from calling suspend() or activate() on itself. Why?
(d) A process must be prevented from calling suspend() on an already suspended process, or calling activate() on a currently active (ready) process. Why?