rcutorture: Better bounds checking for n_barrier_cbs

A negative value for rcutorture.n_barrier_cbs can pass a negative value
to the memory allocator, so this commit instead causes rcu_barrier()
testing to be disabled in this case.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2015-05-14 15:35:43 -07:00
commit d9eba76883