Function lockmgr_lock_flags

freebsd/kern/kern_lock.c:1029–1092

}

int
lockmgr_lock_flags(struct lock *lk, u_int flags, struct lock_object *ilk,
    const char *file, int line)
{
	struct lock_class *class;
	uintptr_t x, tid;
	u_int op;
	bool locked;

	if (KERNEL_PANICKED())
		return (0);

	op = flags & LK_TYPE_MASK;
	locked = false;
	switch (op) {
	case LK_SHARED:
		if (LK_CAN_WITNESS(flags))
			WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER,
			    file, line, flags & LK_INTERLOCK ? ilk : NULL);
		if (__predict_false(lk->lock_object.lo_flags & LK_NOSHARE))
			break;
		x = lockmgr_read_value(lk);
		if (lockmgr_slock_try(lk, &x, flags, true)) {
			lockmgr_note_shared_acquire(lk, 0, 0,
			    file, line, flags);
			locked = true;
		} else {
			return (lockmgr_slock_hard(lk, flags, ilk, file, line,
			    NULL));
		}
		break;
	case LK_EXCLUSIVE:
		if (LK_CAN_WITNESS(flags))
			WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER |
			    LOP_EXCLUSIVE, file, line, flags & LK_INTERLOCK ?
			    ilk : NULL);
		tid = (uintptr_t)curthread;
		if (lockmgr_read_value(lk) == LK_UNLOCKED &&
		    atomic_cmpset_acq_ptr(&lk->lk_lock, LK_UNLOCKED, tid)) {
			lockmgr_note_exclusive_acquire(lk, 0, 0, file, line,
			    flags);
			locked = true;
		} else {
			return (lockmgr_xlock_hard(lk, flags, ilk, file, line,
			    NULL));
		}
		break;
	case LK_UPGRADE:
	case LK_TRYUPGRADE:
		return (lockmgr_upgrade(lk, flags, ilk, file, line, NULL));
	default:
		break;
	}
	if (__predict_true(locked)) {
		if (__predict_false(flags & LK_INTERLOCK)) {
			class = LOCK_CLASS(ilk);
			class->lc_unlock(ilk);
		}