From 6aacd88d1721e12b013ae4ccf4f17609bd5091f3 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sat, 13 Jul 2019 12:27:03 -0700 Subject: rcu/nocb: EXP Check use and usefulness of ->nocb_lock_contended Signed-off-by: Paul E. McKenney --- kernel/rcu/tree_plugin.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 12b14d7a2cf2..97c730753a6d 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -1515,6 +1515,7 @@ static void rcu_nocb_bypass_lock(struct rcu_data *rdp) if (raw_spin_trylock(&rdp->nocb_bypass_lock)) return; atomic_inc(&rdp->nocb_lock_contended); + WARN_ON_ONCE(smp_processor_id() != rdp->cpu); smp_mb__after_atomic(); /* atomic_inc() before lock. */ raw_spin_lock(&rdp->nocb_bypass_lock); smp_mb__before_atomic(); /* atomic_dec() after lock. */ @@ -1533,7 +1534,8 @@ static void rcu_nocb_bypass_lock(struct rcu_data *rdp) */ static void rcu_nocb_wait_contended(struct rcu_data *rdp) { - while (atomic_read(&rdp->nocb_lock_contended)) + WARN_ON_ONCE(smp_processor_id() != rdp->cpu); + while (WARN_ON_ONCE(atomic_read(&rdp->nocb_lock_contended))) cpu_relax(); } -- cgit v1.2.3