locked             16 spinlock.c       lk->locked = 0;
locked             34 spinlock.c       while(xchg(&lk->locked, 1) != 0)
locked             61 spinlock.c       xchg(&lk->locked, 0);
locked             88 spinlock.c       return lock->locked && lock->cpu == cpu;
locked              3 spinlock.h       uint locked;       // Is the lock held?