SOLUTION

If a process is executing in its critical section no other process can execute in its critical section.

A solution to the critical-section problem must satisfy the following three requirements:

Mutual Exclusion: If the process is executing in its critical section, then no other processes can be executing in their critical sections.

Progress: If no process is executing in its critical section and there exist some processes that wish to enter their critical sections, then only those processes that are not executing in their remainder section can participate in the decision of which will enter its critical section next, and this selection cannot be postponed indefinitely.

Bounded Waiting: There exists a bound on the number of times that other processes are allowed to enter their critical sections after a process has made a request to enter its critical section and before that request is granted.