Commit e7a3c8ea authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Paul E. McKenney
Browse files

rcu: Remove full memory barrier on boot time eqs sanity check 



When the boot CPU initializes the per-CPU data on behalf of all possible
CPUs, a sanity check is performed on each of them to make sure none is
initialized in an extended quiescent state.

This check involves a full memory barrier which is useless at this early
boot stage.

Do a plain access instead.

Signed-off-by: default avatarFrederic Weisbecker <frederic@kernel.org>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Reviewed-by: default avatarBoqun Feng <boqun.feng@gmail.com>
Reviewed-by: default avatarNeeraj Upadhyay <neeraj.upadhyay@kernel.org>
parent 33c0860b

kernel/rcu/tree.c

+1 −1
Original line number Diff line number Diff line
@@ -4786,7 +4786,7 @@ rcu_boot_init_percpu_data(int cpu) 
	rdp->grpmask = leaf_node_cpu_bit(rdp->mynode, cpu);

	INIT_WORK(&rdp->strict_work, strict_work_handler);

	WARN_ON_ONCE(ct->dynticks_nesting != 1);

	WARN_ON_ONCE(rcu_dynticks_in_eqs(rcu_dynticks_snap(cpu)));

	WARN_ON_ONCE(rcu_dynticks_in_eqs(ct_dynticks_cpu(cpu)));

	rdp->barrier_seq_snap = rcu_state.barrier_sequence;

	rdp->rcu_ofl_gp_seq = rcu_state.gp_seq;

	rdp->rcu_ofl_gp_state = RCU_GP_CLEANED;