This commit causes the early boot single-CPU synchronize_rcu_expedited()
fastpath to update the rcu_state structure's ->expedited_sequence
counter. This will allow the full-state polled grace-period APIs to
detect all expedited grace periods without the need to track the special
combined polling-only counter, which is another step towards removing
the ->rgos_polled field from the rcu_gp_oldstate, thereby reducing its
size by one third.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
kernel/rcu/tree_exp.h | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
index 1a51f9301ebff..54e05d13d1512 100644
--- a/kernel/rcu/tree_exp.h
+++ b/kernel/rcu/tree_exp.h
@@ -906,6 +906,7 @@ static int rcu_print_task_exp_stall(struct rcu_node *rnp)
void synchronize_rcu_expedited(void)
{
bool boottime = (rcu_scheduler_active == RCU_SCHEDULER_INIT);
+ unsigned long flags;
struct rcu_exp_work rew;
struct rcu_node *rnp;
unsigned long s;
@@ -924,6 +925,11 @@ void synchronize_rcu_expedited(void)
// them, which allows reuse of ->gp_seq_polled_exp_snap.
rcu_poll_gp_seq_start_unlocked(&rcu_state.gp_seq_polled_exp_snap);
rcu_poll_gp_seq_end_unlocked(&rcu_state.gp_seq_polled_exp_snap);
+
+ local_irq_save(flags);
+ WARN_ON_ONCE(num_online_cpus() > 1);
+ rcu_state.expedited_sequence += (1 << RCU_SEQ_CTR_SHIFT);
+ local_irq_restore(flags);
return; // Context allows vacuous grace periods.
}
--
2.31.1.189.g2e36527f23
