[PATCH tip/core/rcu 5/9] rcu: Correctly initialize ->rcu_qs_ctr_snap at online time

["Paul E. McKenney" <paulmck@linux.vnet.ibm.com>]

From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>

The rcu_data structure's ->rcu_qs_ctr_snap field is initialized at
CPU-online time from the current CPU's element of the per-CPU rcu_qs_ctr
variable.  Unfortunately, this is at CPU_UP_PREPARE time, so has nothing
to do with the CPU being onlined.  This commit therefore initializes
this variable from the incoming CPU's element of rcu_qs_ctr.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 kernel/rcu/tree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 1eb1029a5464..48d002d4faac 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3761,7 +3761,7 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
 	rdp->gpnum = rnp->completed; /* Make CPU later note any new GP. */
 	rdp->completed = rnp->completed;
 	rdp->passed_quiesce = false;
-	rdp->rcu_qs_ctr_snap = __this_cpu_read(rcu_qs_ctr);
+	rdp->rcu_qs_ctr_snap = per_cpu(rcu_qs_ctr, cpu);
 	rdp->qs_pending = false;
 	trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("cpuonl"));
 	raw_spin_unlock_irqrestore(&rnp->lock, flags);
-- 
1.8.1.5