tree 7bac429c3cad5f00894746270322d5a4119cea47
parent a10d206ef1a83121ab7430cb196e0376a7145b22
author Paul E. McKenney <paul.mckenney@linaro.org> 1341265321 -0700
committer Paul E. McKenney <paulmck@linux.vnet.ibm.com> 1348411369 -0700

rcu: Add PROVE_RCU_DELAY to provoke difficult races

There have been some recent bugs that were triggered only when
preemptible RCU's __rcu_read_unlock() was preempted just after setting
->rcu_read_lock_nesting to INT_MIN, which is a low-probability event.
Therefore, reproducing those bugs (to say nothing of gaining confidence
in alleged fixes) was quite difficult.  This commit therefore creates
a new debug-only RCU kernel config option that forces a short delay
in __rcu_read_unlock() to increase the probability of those sorts of
bugs occurring.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>