Commit 6aacd88d authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu/nocb: EXP Check use and usefulness of ->nocb_lock_contended 



Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.ibm.com>
parent d1b222c6

kernel/rcu/tree_plugin.h

+3 −1
Original line number Diff line number Diff line
@@ -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();

}