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Single answer: xchgl is a x86 machine instruction that reads…

Single answer: xchgl is a x86 machine instruction that reads a 32bit value from a memory location and sets a new value to the same memory location as a single atomic instruction. The following xchg is the mutual exclusion (mutex) implemented in xv6 os kernel using a xchgl x86 instruction. For your understanding, the machine effects are described in C.   static inline int xchg(volatile int *addr, int newval) { uint result; /* atomic read followed by update in a C version */ result = *addr; *addr = new; return result;} Select one that *CORRECTLY* implements a mutual lock to enter a critical section (mutual exclusion) using the xchg above.

Copy the program below and revise it to make the program pro…

Copy the program below and revise it to make the program produce the same output every time when it executes #include #include #include int value;typedef struct __myarg_t {  int x;  int y;} myarg_t;pthread_t t1,t2;pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;void *work(void *arg) {  myarg_t *m = (myarg_t *) arg; int local1 = m->x; int count = m->y; for (int i = 0; i < count ; i++) {   value = value + local1;  }  return NULL;}int main(){  value = 0; myarg_t arg1 = {2, 1000}; myarg_t arg2 = {3, 1000};  int rc;  value = 0; rc = pthread_create(&t1, NULL, &work, (void*)&arg1);  if (rc < 0) {   perror("pthread creation error for thread t1\n");    return -1;  } rc = pthread_create(&t2, NULL, &work, (void*)&arg2);  if (rc < 0) {   perror("pthread creation error for thread t2\n");    return -1;  }  pthread_join(t1, NULL);  pthread_join(t2, NULL); printf("%d\n", value);  return 0;}