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authorPaul E. McKenney <paul.mckenney@linaro.org>2012-01-12 13:08:18 -0800
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2012-02-21 09:03:45 -0800
commitc44e2cddacc2cf299186bad5697d738ea19668b7 (patch)
tree5346f0dbee43202bf4049e3cda955f3d0cf97cfb /kernel/rcutree.c
parent30fbcc90b02187c55c57ff0ecf57cecbd487d694 (diff)
downloadop-kernel-dev-c44e2cddacc2cf299186bad5697d738ea19668b7.zip
op-kernel-dev-c44e2cddacc2cf299186bad5697d738ea19668b7.tar.gz
rcu: Check for idle-loop entry while in RCU read-side critical section
The inner idle loop is an extended quiescent state for all flavors of RCU, but there have been recent bug involving use of RCU read-side primitives from within the idle loop. Therefore, this commit enlists lockdep-RCU to detect attempts to enter the inner idle loop while in an RCU read-side critical section, emitting a lockdep-RCU splat if so. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcutree.c')
-rw-r--r--kernel/rcutree.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 0569ba1..195bf1f 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -366,6 +366,17 @@ static void rcu_idle_enter_common(struct rcu_dynticks *rdtp, long long oldval)
atomic_inc(&rdtp->dynticks);
smp_mb__after_atomic_inc(); /* Force ordering with next sojourn. */
WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1);
+
+ /*
+ * The idle task is not permitted to enter the idle loop while
+ * in an RCU read-side critical section.
+ */
+ rcu_lockdep_assert(!lock_is_held(&rcu_lock_map),
+ "Illegal idle entry in RCU read-side critical section.");
+ rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map),
+ "Illegal idle entry in RCU-bh read-side critical section.");
+ rcu_lockdep_assert(!lock_is_held(&rcu_sched_lock_map),
+ "Illegal idle entry in RCU-sched read-side critical section.");
}
/**
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