rcu: Eliminate HOTPLUG_CPU #ifdef in favor of IS_ENABLED()

This commit removes a HOTPLUG_CPU #ifdef, replacing it with
IS_ENABLED()-protected return statements.  This relies on the
optimizer to remove any resulting dead code.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

1 files changed, 14 insertions, 25 deletions

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 0628df155970..f2e888c8ec5a 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2335,8 +2335,6 @@ rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp)
         rcu_report_qs_rdp(rdp->cpu, rsp, rdp);
 }
 
-#ifdef CONFIG_HOTPLUG_CPU
-
 /*
  * Send the specified CPU's RCU callbacks to the orphanage.  The
  * specified CPU must be offline, and the caller must hold the
@@ -2347,7 +2345,7 @@ rcu_send_cbs_to_orphanage(int cpu, struct rcu_state *rsp,
                           struct rcu_node *rnp, struct rcu_data *rdp)
 {
         /* No-CBs CPUs do not have orphanable callbacks. */
-        if (rcu_is_nocb_cpu(rdp->cpu))
+        if (!IS_ENABLED(CONFIG_HOTPLUG_CPU) || rcu_is_nocb_cpu(rdp->cpu))
                 return;
 
         /*
@@ -2406,7 +2404,8 @@ static void rcu_adopt_orphan_cbs(struct rcu_state *rsp, unsigned long flags)
         struct rcu_data *rdp = raw_cpu_ptr(rsp->rda);
 
         /* No-CBs CPUs are handled specially. */
-        if (rcu_nocb_adopt_orphan_cbs(rsp, rdp, flags))
+        if (!IS_ENABLED(CONFIG_HOTPLUG_CPU) ||
+            rcu_nocb_adopt_orphan_cbs(rsp, rdp, flags))
                 return;
 
         /* Do the accounting first. */
@@ -2453,6 +2452,9 @@ static void rcu_cleanup_dying_cpu(struct rcu_state *rsp)
         RCU_TRACE(struct rcu_data *rdp = this_cpu_ptr(rsp->rda));
         RCU_TRACE(struct rcu_node *rnp = rdp->mynode);
 
+        if (!IS_ENABLED(CONFIG_HOTPLUG_CPU))
+                return;
+
         RCU_TRACE(mask = rdp->grpmask);
         trace_rcu_grace_period(rsp->name,
                                rnp->gpnum + 1 - !!(rnp->qsmask & mask),
@@ -2481,7 +2483,8 @@ static void rcu_cleanup_dead_rnp(struct rcu_node *rnp_leaf)
         long mask;
         struct rcu_node *rnp = rnp_leaf;
 
-        if (rnp->qsmaskinit || rcu_preempt_has_tasks(rnp))
+        if (!IS_ENABLED(CONFIG_HOTPLUG_CPU) ||
+            rnp->qsmaskinit || rcu_preempt_has_tasks(rnp))
                 return;
         for (;;) {
                 mask = rnp->grpmask;
@@ -2512,6 +2515,9 @@ static void rcu_cleanup_dying_idle_cpu(int cpu, struct rcu_state *rsp)
         struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
         struct rcu_node *rnp = rdp->mynode;  /* Outgoing CPU's rdp & rnp. */
 
+        if (!IS_ENABLED(CONFIG_HOTPLUG_CPU))
+                return;
+
         /* Remove outgoing CPU from mask in the leaf rcu_node structure. */
         mask = rdp->grpmask;
         raw_spin_lock_irqsave(&rnp->lock, flags);
@@ -2533,6 +2539,9 @@ static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp)
         struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
         struct rcu_node *rnp = rdp->mynode;  /* Outgoing CPU's rdp & rnp. */
 
+        if (!IS_ENABLED(CONFIG_HOTPLUG_CPU))
+                return;
+
         /* Adjust any no-longer-needed kthreads. */
         rcu_boost_kthread_setaffinity(rnp, -1);
 
@@ -2547,26 +2556,6 @@ static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp)
                   cpu, rdp->qlen, rdp->nxtlist);
 }
 
-#else /* #ifdef CONFIG_HOTPLUG_CPU */
-
-static void rcu_cleanup_dying_cpu(struct rcu_state *rsp)
-{
-}
-
-static void __maybe_unused rcu_cleanup_dead_rnp(struct rcu_node *rnp_leaf)
-{
-}
-
-static void rcu_cleanup_dying_idle_cpu(int cpu, struct rcu_state *rsp)
-{
-}
-
-static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp)
-{
-}
-
-#endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
-
 /*
  * Invoke any RCU callbacks that have made it to the end of their grace
  * period.  Thottle as specified by rdp->blimit.