patches/rcu-Use-a-raw_spinlock_t-for-kfree-batching.patch

From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Fri, 14 Feb 2020 18:51:43 +0100
Subject: [PATCH] rcu: Use a raw_spinlock_t for kfree batching

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 kernel/rcu/tree.c |   26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2719,7 +2719,7 @@ struct kfree_rcu_cpu_work {
 struct kfree_rcu_cpu {
 	struct rcu_head *head;
 	struct kfree_rcu_cpu_work krw_arr[KFREE_N_BATCHES];
-	spinlock_t lock;
+	raw_spinlock_t lock;
 	struct delayed_work monitor_work;
 	bool monitor_todo;
 	bool initialized;
@@ -2741,10 +2741,10 @@ static void kfree_rcu_work(struct work_s
 	krwp = container_of(to_rcu_work(work),
 			    struct kfree_rcu_cpu_work, rcu_work);
 	krcp = krwp->krcp;
-	spin_lock_irqsave(&krcp->lock, flags);
+	raw_spin_lock_irqsave(&krcp->lock, flags);
 	head = krwp->head_free;
 	krwp->head_free = NULL;
-	spin_unlock_irqrestore(&krcp->lock, flags);
+	raw_spin_unlock_irqrestore(&krcp->lock, flags);
 
 	// List "head" is now private, so traverse locklessly.
 	for (; head; head = next) {
@@ -2803,14 +2803,14 @@ static inline void kfree_rcu_drain_unloc
 	krcp->monitor_todo = false;
 	if (queue_kfree_rcu_work(krcp)) {
 		// Success! Our job is done here.
-		spin_unlock_irqrestore(&krcp->lock, flags);
+		raw_spin_unlock_irqrestore(&krcp->lock, flags);
 		return;
 	}
 
 	// Previous RCU batch still in progress, try again later.
 	krcp->monitor_todo = true;
 	schedule_delayed_work(&krcp->monitor_work, KFREE_DRAIN_JIFFIES);
-	spin_unlock_irqrestore(&krcp->lock, flags);
+	raw_spin_unlock_irqrestore(&krcp->lock, flags);
 }
 
 /*
@@ -2823,11 +2823,11 @@ static void kfree_rcu_monitor(struct wor
 	struct kfree_rcu_cpu *krcp = container_of(work, struct kfree_rcu_cpu,
 						 monitor_work.work);
 
-	spin_lock_irqsave(&krcp->lock, flags);
+	raw_spin_lock_irqsave(&krcp->lock, flags);
 	if (krcp->monitor_todo)
 		kfree_rcu_drain_unlock(krcp, flags);
 	else
-		spin_unlock_irqrestore(&krcp->lock, flags);
+		raw_spin_unlock_irqrestore(&krcp->lock, flags);
 }
 
 /*
@@ -2852,7 +2852,7 @@ void kfree_call_rcu(struct rcu_head *hea
 	local_irq_save(flags);	// For safely calling this_cpu_ptr().
 	krcp = this_cpu_ptr(&krc);
 	if (krcp->initialized)
-		spin_lock(&krcp->lock);
+		raw_spin_lock(&krcp->lock);
 
 	// Queue the object but don't yet schedule the batch.
 	if (debug_rcu_head_queue(head)) {
@@ -2874,7 +2874,7 @@ void kfree_call_rcu(struct rcu_head *hea
 
 unlock_return:
 	if (krcp->initialized)
-		spin_unlock(&krcp->lock);
+		raw_spin_unlock(&krcp->lock);
 	local_irq_restore(flags);
 }
 EXPORT_SYMBOL_GPL(kfree_call_rcu);
@@ -2887,15 +2887,15 @@ void __init kfree_rcu_scheduler_running(
 	for_each_online_cpu(cpu) {
 		struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu);
 
-		spin_lock_irqsave(&krcp->lock, flags);
+		raw_spin_lock_irqsave(&krcp->lock, flags);
 		if (!krcp->head || krcp->monitor_todo) {
-			spin_unlock_irqrestore(&krcp->lock, flags);
+			raw_spin_unlock_irqrestore(&krcp->lock, flags);
 			continue;
 		}
 		krcp->monitor_todo = true;
 		schedule_delayed_work_on(cpu, &krcp->monitor_work,
 					 KFREE_DRAIN_JIFFIES);
-		spin_unlock_irqrestore(&krcp->lock, flags);
+		raw_spin_unlock_irqrestore(&krcp->lock, flags);
 	}
 }
 
@@ -3780,7 +3780,7 @@ static void __init kfree_rcu_batch_init(
 	for_each_possible_cpu(cpu) {
 		struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu);
 
-		spin_lock_init(&krcp->lock);
+		raw_spin_lock_init(&krcp->lock);
 		for (i = 0; i < KFREE_N_BATCHES; i++)
 			krcp->krw_arr[i].krcp = krcp;
 		INIT_DELAYED_WORK(&krcp->monitor_work, kfree_rcu_monitor);