From c44e2cddacc2cf299186bad5697d738ea19668b7 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 12 Jan 2012 13:08:18 -0800 Subject: [PATCH] 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 Signed-off-by: Paul E. McKenney --- kernel/rcutree.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 0569ba11e35a..195bf1fb59ea 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."); } /** -- 2.39.5