[RFC v2 2/5] rcu: Use for_each_leaf_node_cpu() in RCU stall checking

[Boqun Feng]

Use for_each_leaf_node_cpu() in RCU stall checking code, to save some
extra checks, based on the fact that ->qsmask is mostly more sparse than
cpu_possible_mask.

Signed-off-by: Boqun Feng <boqun.f...@gmail.com>
---
 kernel/rcu/tree.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index b56e2dc31ba5..4e5b81c843de 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1417,10 +1417,11 @@ static void rcu_dump_cpu_stacks(struct rcu_state *rsp)
 
        rcu_for_each_leaf_node(rsp, rnp) {
                raw_spin_lock_irqsave_rcu_node(rnp, flags);
-               for_each_leaf_node_possible_cpu(rnp, cpu)
-                       if (rnp->qsmask & leaf_node_cpu_bit(rnp, cpu))
-                               if (!trigger_single_cpu_backtrace(cpu))
-                                       dump_cpu_task(cpu);
+
+               for_each_leaf_node_cpu(rnp, rnp->qsmask, cpu)
+                       if (!trigger_single_cpu_backtrace(cpu))
+                               dump_cpu_task(cpu);
+
                raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
        }
 }
@@ -1490,13 +1491,12 @@ static void print_other_cpu_stall(struct rcu_state 
*rsp, unsigned long gpnum)
        rcu_for_each_leaf_node(rsp, rnp) {
                raw_spin_lock_irqsave_rcu_node(rnp, flags);
                ndetected += rcu_print_task_stall(rnp);
-               if (rnp->qsmask != 0) {
-                       for_each_leaf_node_possible_cpu(rnp, cpu)
-                               if (rnp->qsmask & leaf_node_cpu_bit(rnp, cpu)) {
-                                       print_cpu_stall_info(rsp, cpu);
-                                       ndetected++;
-                               }
+
+               for_each_leaf_node_cpu(rnp, rnp->qsmask, cpu) {
+                       print_cpu_stall_info(rsp, cpu);
+                       ndetected++;
                }
+
                raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
        }
 
-- 
2.10.2