[tip: core/rcu] refscale: Add acqrel, lock, and lock-irq

[tip-bot2 for Paul E. McKenney]

The following commit has been merged into the core/rcu branch of tip:

Commit-ID:     e9b800db96fa40170c5607d8968b2ec6212c2026
Gitweb:        https://git.kernel.org/tip/e9b800db96fa40170c5607d8968b2ec6212c2026
Author:        Paul E. McKenney <paulmck@xxxxxxxxxx>
AuthorDate:    Wed, 10 Mar 2021 18:02:36 -08:00
Committer:     Paul E. McKenney <paulmck@xxxxxxxxxx>
CommitterDate: Mon, 10 May 2021 16:05:05 -07:00

refscale: Add acqrel, lock, and lock-irq

This commit adds scale_type of acqrel, lock, and lock-irq to
test acquisition and release.  Note that the refscale.nreaders=1
module parameter is required if you wish to test uncontended locking.
In contrast, acqrel uses a per-CPU variable, so should be just fine with
large values of the refscale.nreaders=1 module parameter.

Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
 kernel/rcu/refscale.c | 109 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 107 insertions(+), 2 deletions(-)

diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c
index 02dd976..313d454 100644
--- a/kernel/rcu/refscale.c
+++ b/kernel/rcu/refscale.c
@@ -362,6 +362,111 @@ static struct ref_scale_ops rwsem_ops = {
 	.name		= "rwsem"
 };
 
+// Definitions for global spinlock
+static DEFINE_SPINLOCK(test_lock);
+
+static void ref_lock_section(const int nloops)
+{
+	int i;
+
+	preempt_disable();
+	for (i = nloops; i >= 0; i--) {
+		spin_lock(&test_lock);
+		spin_unlock(&test_lock);
+	}
+	preempt_enable();
+}
+
+static void ref_lock_delay_section(const int nloops, const int udl, const int ndl)
+{
+	int i;
+
+	preempt_disable();
+	for (i = nloops; i >= 0; i--) {
+		spin_lock(&test_lock);
+		un_delay(udl, ndl);
+		spin_unlock(&test_lock);
+	}
+	preempt_enable();
+}
+
+static struct ref_scale_ops lock_ops = {
+	.readsection	= ref_lock_section,
+	.delaysection	= ref_lock_delay_section,
+	.name		= "lock"
+};
+
+// Definitions for global irq-save spinlock
+
+static void ref_lock_irq_section(const int nloops)
+{
+	unsigned long flags;
+	int i;
+
+	preempt_disable();
+	for (i = nloops; i >= 0; i--) {
+		spin_lock_irqsave(&test_lock, flags);
+		spin_unlock_irqrestore(&test_lock, flags);
+	}
+	preempt_enable();
+}
+
+static void ref_lock_irq_delay_section(const int nloops, const int udl, const int ndl)
+{
+	unsigned long flags;
+	int i;
+
+	preempt_disable();
+	for (i = nloops; i >= 0; i--) {
+		spin_lock_irqsave(&test_lock, flags);
+		un_delay(udl, ndl);
+		spin_unlock_irqrestore(&test_lock, flags);
+	}
+	preempt_enable();
+}
+
+static struct ref_scale_ops lock_irq_ops = {
+	.readsection	= ref_lock_irq_section,
+	.delaysection	= ref_lock_irq_delay_section,
+	.name		= "lock-irq"
+};
+
+// Definitions acquire-release.
+static DEFINE_PER_CPU(unsigned long, test_acqrel);
+
+static void ref_acqrel_section(const int nloops)
+{
+	unsigned long x;
+	int i;
+
+	preempt_disable();
+	for (i = nloops; i >= 0; i--) {
+		x = smp_load_acquire(this_cpu_ptr(&test_acqrel));
+		smp_store_release(this_cpu_ptr(&test_acqrel), x + 1);
+	}
+	preempt_enable();
+}
+
+static void ref_acqrel_delay_section(const int nloops, const int udl, const int ndl)
+{
+	unsigned long x;
+	int i;
+
+	preempt_disable();
+	for (i = nloops; i >= 0; i--) {
+		x = smp_load_acquire(this_cpu_ptr(&test_acqrel));
+		un_delay(udl, ndl);
+		smp_store_release(this_cpu_ptr(&test_acqrel), x + 1);
+	}
+	preempt_enable();
+}
+
+static struct ref_scale_ops acqrel_ops = {
+	.readsection	= ref_acqrel_section,
+	.delaysection	= ref_acqrel_delay_section,
+	.name		= "acqrel"
+};
+
 static void rcu_scale_one_reader(void)
 {
 	if (readdelay <= 0)
@@ -653,8 +758,8 @@ ref_scale_init(void)
 	long i;
 	int firsterr = 0;
 	static struct ref_scale_ops *scale_ops[] = {
-		&rcu_ops, &srcu_ops, &rcu_trace_ops, &rcu_tasks_ops,
-		&refcnt_ops, &rwlock_ops, &rwsem_ops,
+		&rcu_ops, &srcu_ops, &rcu_trace_ops, &rcu_tasks_ops, &refcnt_ops, &rwlock_ops,
+		&rwsem_ops, &lock_ops, &lock_irq_ops, &acqrel_ops,
 	};
 
 	if (!torture_init_begin(scale_type, verbose))