[PATCH tip/core/rcu 03/10] rcu: Switch ->tick_nohz_enabled_snap to rcu_data structure

[Paul E. McKenney]

This commit removes ->tick_nohz_enabled_snap from the rcu_dynticks
structure and updates the code to access it from the rcu_data
structure.

Signed-off-by: Paul E. McKenney <paul...@linux.vnet.ibm.com>
---
 kernel/rcu/tree.h        |  1 -
 kernel/rcu/tree_plugin.h | 10 +++++-----
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index d35cd9677b08..5d447ceba769 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -53,7 +53,6 @@ struct rcu_dynticks {
                                    /* Last jiffy CBs were accelerated. */
        unsigned long last_advance_all;
                                    /* Last jiffy CBs were all advanced. */
-       int tick_nohz_enabled_snap; /* Previously seen value from sysfs. */
 #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
 };
 
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 978ce3539809..6511032371c1 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1681,7 +1681,7 @@ int rcu_needs_cpu(u64 basemono, u64 *nextevt)
 static void rcu_prepare_for_idle(void)
 {
        bool needwake;
-       struct rcu_data *rdp;
+       struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
        struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
        struct rcu_node *rnp;
        int tne;
@@ -1692,10 +1692,10 @@ static void rcu_prepare_for_idle(void)
 
        /* Handle nohz enablement switches conservatively. */
        tne = READ_ONCE(tick_nohz_active);
-       if (tne != rdtp->tick_nohz_enabled_snap) {
+       if (tne != rdp->tick_nohz_enabled_snap) {
                if (rcu_cpu_has_callbacks(NULL))
                        invoke_rcu_core(); /* force nohz to see update. */
-               rdtp->tick_nohz_enabled_snap = tne;
+               rdp->tick_nohz_enabled_snap = tne;
                return;
        }
        if (!tne)
@@ -1721,7 +1721,6 @@ static void rcu_prepare_for_idle(void)
        if (rdtp->last_accelerate == jiffies)
                return;
        rdtp->last_accelerate = jiffies;
-       rdp = this_cpu_ptr(&rcu_data);
        if (rcu_segcblist_pend_cbs(&rdp->cblist)) {
                rnp = rdp->mynode;
                raw_spin_lock_rcu_node(rnp); /* irqs already disabled. */
@@ -1765,6 +1764,7 @@ static void rcu_idle_count_callbacks_posted(void)
 
 static void print_cpu_stall_fast_no_hz(char *cp, int cpu)
 {
+       struct rcu_data *rdp = &per_cpu(rcu_data, cpu);
        struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu);
        unsigned long nlpd = rdtp->nonlazy_posted - rdtp->nonlazy_posted_snap;
 
@@ -1772,7 +1772,7 @@ static void print_cpu_stall_fast_no_hz(char *cp, int cpu)
                rdtp->last_accelerate & 0xffff, jiffies & 0xffff,
                ulong2long(nlpd),
                rdtp->all_lazy ? 'L' : '.',
-               rdtp->tick_nohz_enabled_snap ? '.' : 'D');
+               rdp->tick_nohz_enabled_snap ? '.' : 'D');
 }
 
 #else /* #ifdef CONFIG_RCU_FAST_NO_HZ */
-- 
2.17.1