The atomic fetch-and-set x, y instruction unconditionally sets the memory location x to 1 and fetches the old value of x in y without allowing any intervening access to the memory location x. Consider the following implementation of P and V functions on a binary semaphore S. void P (binary_semaphore *S) { unsigned y;unsigned *x = & (S -> value); do { fetch-and-set x, y; } while (y); } void V (binary_semaphore *S) { s - > value = 0; } Which one of the following is true?

Instead of using fetch-and-set, a pair of normal load/ store can be used

The implementation may not work, if context switching is disabled in P

Instead of using fetch-and-set, a pair of normal load/ store can be used

The implementation of V is wrong

The code does not implement a binary semaphore

The atomic fetch-and-set x, y instruction unconditionally sets the mem

1.	The atomic fetch-and-set x, y instruction unconditionally sets the memory location x to 1 and fetches the old value of x in y without allowing any intervening access to the memory location x. Consider the following implementation of P and V functions on a binary semaphore S. void P (binary_semaphore S) { unsigned y;unsigned x = & (S -> value); do { fetch-and-set x, y; } while (y); } void V (binary_semaphore *S) { s - > value = 0; } Which one of the following is true?
A.	The implementation may not work, if context switching is disabled in P
B.	Instead of using fetch-and-set, a pair of normal load/ store can be used
C.	The implementation of V is wrong
D.	The code does not implement a binary semaphore
Answer» B. Instead of using fetch-and-set, a pair of normal load/ store can be used

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