linux-kernel - [PATCH tip/core/rcu 24/52] rcu: Remove rsp parameter from CPU hotplug functions

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Date:   Wed, 29 Aug 2018 15:38:26 -0700
From:   "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:     linux-kernel@...r.kernel.org
Cc:     mingo@...nel.org, jiangshanlai@...il.com, dipankar@...ibm.com,
        akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
        josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
        rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
        fweisbec@...il.com, oleg@...hat.com, joel@...lfernandes.org,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 24/52] rcu: Remove rsp parameter from CPU hotplug functions

There now is only one rcu_state structure in a given build of the
Linux kernel, so there is no need to pass it as a parameter to RCU's
functions.  This commit therefore removes the rsp parameter from
rcu_cleanup_dying_cpu() and rcu_cleanup_dead_cpu().  And, as long as
we are in the neighborhood, inlines them into rcutree_dying_cpu() and
rcutree_dead_cpu(), respectively.  This also eliminates a pair of
for_each_rcu_flavor() loops.

Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
 kernel/rcu/tree.c | 43 +++++++++++--------------------------------
 1 file changed, 11 insertions(+), 32 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index c7e58f6ac666..c38c9dcb98fe 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2401,20 +2401,22 @@ rcu_check_quiescent_state(struct rcu_data *rdp)
 }
 
 /*
- * Trace the fact that this CPU is going offline.
+ * Near the end of the offline process.  Trace the fact that this CPU
+ * is going offline.
  */
-static void rcu_cleanup_dying_cpu(struct rcu_state *rsp)
+int rcutree_dying_cpu(unsigned int cpu)
 {
 	RCU_TRACE(bool blkd;)
 	RCU_TRACE(struct rcu_data *rdp = this_cpu_ptr(&rcu_data);)
 	RCU_TRACE(struct rcu_node *rnp = rdp->mynode;)
 
 	if (!IS_ENABLED(CONFIG_HOTPLUG_CPU))
-		return;
+		return 0;
 
 	RCU_TRACE(blkd = !!(rnp->qsmask & rdp->grpmask);)
-	trace_rcu_grace_period(rsp->name, rnp->gp_seq,
+	trace_rcu_grace_period(rcu_state.name, rnp->gp_seq,
 			       blkd ? TPS("cpuofl") : TPS("cpuofl-bgp"));
+	return 0;
 }
 
 /*
@@ -2468,16 +2470,19 @@ static void rcu_cleanup_dead_rnp(struct rcu_node *rnp_leaf)
  * There can only be one CPU hotplug operation at a time, so no need for
  * explicit locking.
  */
-static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp)
+int rcutree_dead_cpu(unsigned int cpu)
 {
 	struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
 	struct rcu_node *rnp = rdp->mynode;  /* Outgoing CPU's rdp & rnp. */
 
 	if (!IS_ENABLED(CONFIG_HOTPLUG_CPU))
-		return;
+		return 0;
 
 	/* Adjust any no-longer-needed kthreads. */
 	rcu_boost_kthread_setaffinity(rnp, -1);
+	/* Do any needed no-CB deferred wakeups from this CPU. */
+	do_nocb_deferred_wakeup(per_cpu_ptr(&rcu_data, cpu));
+	return 0;
 }
 
 /*
@@ -3513,32 +3518,6 @@ int rcutree_offline_cpu(unsigned int cpu)
 	return 0;
 }
 
-/*
- * Near the end of the offline process.  We do only tracing here.
- */
-int rcutree_dying_cpu(unsigned int cpu)
-{
-	struct rcu_state *rsp;
-
-	for_each_rcu_flavor(rsp)
-		rcu_cleanup_dying_cpu(rsp);
-	return 0;
-}
-
-/*
- * The outgoing CPU is gone and we are running elsewhere.
- */
-int rcutree_dead_cpu(unsigned int cpu)
-{
-	struct rcu_state *rsp;
-
-	for_each_rcu_flavor(rsp) {
-		rcu_cleanup_dead_cpu(cpu, rsp);
-		do_nocb_deferred_wakeup(per_cpu_ptr(&rcu_data, cpu));
-	}
-	return 0;
-}
-
 static DEFINE_PER_CPU(int, rcu_cpu_started);
 
 /*
-- 
2.17.1