From: Paul E. McKenney <paul.mckenney@linaro.org>
Date: Mon, 2 Jul 2012 21:42:01 +0000 (-0700)
Subject: rcu: Add PROVE_RCU_DELAY to provoke difficult races
X-Git-Tag: omap-for-v3.7-rc1/fixes-cpufreq-signed~101^2~1^2~2^3~16
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e3ebfb96f396731ca2d0b108785d5da31b53ab00;p=pandora-kernel.git

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>
---

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