Critical section with sephamores

Question

1. Take this pseudo code,

   Semaphore S <- 0 
   non-critical section 
   wait(S)
   critical section 
   signal(S)
   

Does this solution to the critical section problem support mutual exclusion only?

I know that there is no freedom from deadlock since the critical section is never reached, however would that also mean that it does not support mutual exclusion.

Answer 1

Mutual Exclusion means that only 1 thread(or process) can enter the Critical Section. So by definition the code does not violate mutual exclusion.

The important thing to note here is that all threads, would be in busy-waiting state, and there is no progress at all, but actually there is no deadlock, because one of the 4 must occur conditions for deadlock is CIRCULAR WAIT. But its not that threads are waiting for each other in this case.