From: Paul E. McKenney Date: Sat, 13 Jul 2019 19:27:03 +0000 (-0700) Subject: rcu/nocb: EXP Check use and usefulness of ->nocb_lock_contended X-Git-Tag: v5.4-rc1~181^2~1^2^2~7 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=6aacd88d1721e12b013ae4ccf4f17609bd5091f3;p=thirdparty%2Fkernel%2Flinux.git rcu/nocb: EXP Check use and usefulness of ->nocb_lock_contended Signed-off-by: Paul E. McKenney --- diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 12b14d7a2cf2f..97c730753a6d0 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(); }