double_checking: silence false positives caused by threading

double_checking: silence false positives caused by threading

A common thing in the kernel is when people do:

	if (!foo->bar)
		return;
	spin_lock();
	/* test again with the lock held */
	if (!foo->bar) {
		spin_unlock();
		return;
	}

This causes false positives in this check.  We can silence them by looking
for a synchronize function call in the lines just prior to the second
check.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>