rcutorture: Allow rcutorture without RCU Tasks Trace

Unless a kernel builds rcutorture, whether built-in or as a module, that
kernel is also built with CONFIG_TASKS_TRACE_RCU, whether anything else
needs Tasks Trace RCU or not.  This unnecessarily increases kernel size.
This commit therefore decouples the presence of rcutorture from the
presence of RCU Tasks Trace.

However, there is a need to select CONFIG_TASKS_TRACE_RCU for
testing purposes.  Except that casual users must not be bothered with
questions -- for them, this needs to be fully automated.  There is thus
a CONFIG_FORCE_TASKS_TRACE_RCU that selects CONFIG_TASKS_TRACE_RCU,
is user-selectable, but which depends on CONFIG_RCU_EXPERT.

[ paulmck: Apply kernel test robot feedback. ]

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

1 files changed, 56 insertions, 45 deletions

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 55d049c39608..7dd3e14ec907 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -738,6 +738,48 @@ static struct rcu_torture_ops busted_srcud_ops = {
 };
 
 /*
+ * Definitions for trivial CONFIG_PREEMPT=n-only torture testing.
+ * This implementation does not necessarily work well with CPU hotplug.
+ */
+
+static void synchronize_rcu_trivial(void)
+{
+	int cpu;
+
+	for_each_online_cpu(cpu) {
+		rcutorture_sched_setaffinity(current->pid, cpumask_of(cpu));
+		WARN_ON_ONCE(raw_smp_processor_id() != cpu);
+	}
+}
+
+static int rcu_torture_read_lock_trivial(void) __acquires(RCU)
+{
+	preempt_disable();
+	return 0;
+}
+
+static void rcu_torture_read_unlock_trivial(int idx) __releases(RCU)
+{
+	preempt_enable();
+}
+
+static struct rcu_torture_ops trivial_ops = {
+	.ttype		= RCU_TRIVIAL_FLAVOR,
+	.init		= rcu_sync_torture_init,
+	.readlock	= rcu_torture_read_lock_trivial,
+	.read_delay	= rcu_read_delay,  /* just reuse rcu's version. */
+	.readunlock	= rcu_torture_read_unlock_trivial,
+	.readlock_held	= torture_readlock_not_held,
+	.get_gp_seq	= rcu_no_completed,
+	.sync		= synchronize_rcu_trivial,
+	.exp_sync	= synchronize_rcu_trivial,
+	.fqs		= NULL,
+	.stats		= NULL,
+	.irq_capable	= 1,
+	.name		= "trivial"
+};
+
+/*
  * Definitions for RCU-tasks torture testing.
  */
 
@@ -781,48 +823,6 @@ static struct rcu_torture_ops tasks_ops = {
 };
 
 /*
- * Definitions for trivial CONFIG_PREEMPT=n-only torture testing.
- * This implementation does not necessarily work well with CPU hotplug.
- */
-
-static void synchronize_rcu_trivial(void)
-{
-	int cpu;
-
-	for_each_online_cpu(cpu) {
-		rcutorture_sched_setaffinity(current->pid, cpumask_of(cpu));
-		WARN_ON_ONCE(raw_smp_processor_id() != cpu);
-	}
-}
-
-static int rcu_torture_read_lock_trivial(void) __acquires(RCU)
-{
-	preempt_disable();
-	return 0;
-}
-
-static void rcu_torture_read_unlock_trivial(int idx) __releases(RCU)
-{
-	preempt_enable();
-}
-
-static struct rcu_torture_ops trivial_ops = {
-	.ttype		= RCU_TRIVIAL_FLAVOR,
-	.init		= rcu_sync_torture_init,
-	.readlock	= rcu_torture_read_lock_trivial,
-	.read_delay	= rcu_read_delay,  /* just reuse rcu's version. */
-	.readunlock	= rcu_torture_read_unlock_trivial,
-	.readlock_held	= torture_readlock_not_held,
-	.get_gp_seq	= rcu_no_completed,
-	.sync		= synchronize_rcu_trivial,
-	.exp_sync	= synchronize_rcu_trivial,
-	.fqs		= NULL,
-	.stats		= NULL,
-	.irq_capable	= 1,
-	.name		= "trivial"
-};
-
-/*
  * Definitions for rude RCU-tasks torture testing.
  */
 
@@ -851,6 +851,8 @@ static struct rcu_torture_ops tasks_rude_ops = {
 	.name		= "tasks-rude"
 };
 
+#ifdef CONFIG_TASKS_TRACE_RCU
+
 /*
  * Definitions for tracing RCU-tasks torture testing.
  */
@@ -893,6 +895,15 @@ static struct rcu_torture_ops tasks_tracing_ops = {
 	.name		= "tasks-tracing"
 };
 
+#define TASKS_TRACING_OPS &tasks_tracing_ops,
+
+#else // #ifdef CONFIG_TASKS_TRACE_RCU
+
+#define TASKS_TRACING_OPS
+
+#endif // #else #ifdef CONFIG_TASKS_TRACE_RCU
+
+
 static unsigned long rcutorture_seq_diff(unsigned long new, unsigned long old)
 {
 	if (!cur_ops->gp_diff)
@@ -3096,9 +3107,9 @@ rcu_torture_init(void)
 	int flags = 0;
 	unsigned long gp_seq = 0;
 	static struct rcu_torture_ops *torture_ops[] = {
-		&rcu_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
-		&busted_srcud_ops, &tasks_ops, &tasks_rude_ops,
-		&tasks_tracing_ops, &trivial_ops,
+		&rcu_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops, &busted_srcud_ops,
+		&tasks_ops, &tasks_rude_ops, TASKS_TRACING_OPS
+		&trivial_ops,
 	};
 
 	if (!torture_init_begin(torture_type, verbose))