rcuscale: Allow rcuscale without RCU Tasks Rude/Trace

Currently, a CONFIG_PREEMPT_NONE=y kernel substitutes normal RCU for
RCU Tasks Rude and RCU Tasks Trace.  Unless that kernel builds rcuscale,
whether built-in or as a module, in which case these RCU Tasks flavors are
(unnecessarily) built in.  This both increases kernel size and increases
the complexity of certain tracing operations.  This commit therefore
decouples the presence of rcuscale from the presence of RCU Tasks Rude
and RCU Tasks Trace.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

kernel/rcu/Kconfig.debug

@@ -28,8 +28,6 @@ config RCU_SCALE_TEST
 	depends on DEBUG_KERNEL
 	select TORTURE_TEST
 	select SRCU
-	select TASKS_RUDE_RCU
-	select TASKS_TRACE_RCU
 	default n
 	help
 	  This option provides a kernel module that runs performance

kernel/rcu/rcuscale.c

@@ -305,6 +305,8 @@ static struct rcu_scale_ops tasks_ops = {
 
 #endif // #else // #ifdef CONFIG_TASKS_RCU
 
+#ifdef CONFIG_TASKS_TRACE_RCU
+
 /*
  * Definitions for RCU-tasks-trace scalability testing.
  */
@@ -334,6 +336,14 @@ static struct rcu_scale_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 rcuscale_seq_diff(unsigned long new, unsigned long old)
 {
 	if (!cur_ops->gp_diff)
@@ -807,7 +817,7 @@ rcu_scale_init(void)
 	long i;
 	int firsterr = 0;
 	static struct rcu_scale_ops *scale_ops[] = {
-		&rcu_ops, &srcu_ops, &srcud_ops, TASKS_OPS &tasks_tracing_ops
+		&rcu_ops, &srcu_ops, &srcud_ops, TASKS_OPS TASKS_TRACING_OPS
 	};
 
 	if (!torture_init_begin(scale_type, verbose))

tools/testing/selftests/rcutorture/configs/rcuscale/CFcommon

 CONFIG_RCU_SCALE_TEST=y
 CONFIG_PRINTK_TIME=y
-CONFIG_TASKS_RCU_GENERIC=y
 CONFIG_FORCE_TASKS_RCU=y
 #CHECK#CONFIG_TASKS_RCU=y
+CONFIG_FORCE_TASKS_TRACE_RCU=y
+#CHECK#CONFIG_TASKS_TRACE_RCU=y