rcu: Adjust for unconditional ->completed assignment

Now that the rcu_node structures' ->completed fields are unconditionally
assigned at grace-period cleanup time, they should already have the
correct value for the new grace period at grace-period initialization
time.  This commit therefore inserts a WARN_ON_ONCE() to verify this
invariant.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index f0f3a18c0a20..a2eadd04fb29 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -1080,6 +1080,7 @@ static int rcu_gp_init(struct rcu_state *rsp)
                 rcu_preempt_check_blocked_tasks(rnp);
                 rnp->qsmask = rnp->qsmaskinit;
                 rnp->gpnum = rsp->gpnum;
+                WARN_ON_ONCE(rnp->completed != rsp->completed);
                 rnp->completed = rsp->completed;
                 if (rnp == rdp->mynode)
                         rcu_start_gp_per_cpu(rsp, rnp, rdp);
@@ -2777,7 +2778,8 @@ static void __init rcu_init_one(struct rcu_state *rsp,
                         raw_spin_lock_init(&rnp->fqslock);
                         lockdep_set_class_and_name(&rnp->fqslock,
                                                    &rcu_fqs_class[i], fqs[i]);
-                        rnp->gpnum = 0;
+                        rnp->gpnum = rsp->gpnum;
+                        rnp->completed = rsp->completed;
                         rnp->qsmask = 0;
                         rnp->qsmaskinit = 0;
                         rnp->grplo = j * cpustride;