Does the following lock implemented correctly? If not, point out the problems and justify your answers.

typedef struct __lock_t

{

int flag; // flag == 0 means resource is free; otherwise, resource is not available

}

lock_t;

void init(lock_t *lock)

{

lock->flag = 1;

}

void acquire(lock_t *lock)

{

while(xchg(&lock->flag, 1) == 0) ; // spin-wait (do nothing)

}

void release(lock_t *lock)

{

lock->flag = 1;

}