rcutorture: Check for ->up_read() without matching ->down_read()

rcutorture: Check for ->up_read() without matching ->down_read()

This commit creates counters in the rcu_torture_one_read_state_updown
structure that check for a call to ->up_read() that lacks a matching
call to ->down_read().

While in the area, add end-of-run cleanup code that prevents calls to
rcu_torture_updown_hrt() from happening after the test has moved on.  Yes,
the srcu_barrier() at the end of the test will wait for them, but this
could result in confusing states, statistics, and diagnostic information.
So explicitly wait for them before we get to the end-of-test output.

[ paulmck: Apply kernel test robot feedback. ]
[ joel: Apply Boqun's fix for counter increment ordering. ]

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>