diff mbox

[tip/core/rcu,24/47] rcu: Check for idle-loop entry while in RCU read-side critical section

Message ID 1328319922-30828-24-git-send-email-paulmck@linux.vnet.ibm.com
State Accepted
Commit c44e2cddacc2cf299186bad5697d738ea19668b7
Headers show

Commit Message

Paul E. McKenney Feb. 4, 2012, 1:44 a.m. UTC 
From: "Paul E. McKenney" <paul.mckenney@linaro.org>

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>
---
 kernel/rcutree.c |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)
diff mbox

Patch

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.");
 }
 
 /**