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>

diff --git a/kernel/rcu/Kconfig b/kernel/rcu/Kconfig
index 4f665ae0cf55d10cbd48317d06f80c3f4abd6320..2befd328e6a0ef45e28c6d162dfe4656f91c260b 100644 (file)
--- a/kernel/rcu/Kconfig
+++ b/kernel/rcu/Kconfig
@@ -95,15 +95,23 @@ config TASKS_RUDE_RCU
          switches on all online CPUs, including idle ones, so use
          with caution.
 
-config TASKS_TRACE_RCU
-       def_bool 0
-       select IRQ_WORK
+config FORCE_TASKS_TRACE_RCU
+       bool "Force selection of Tasks Trace RCU"
+       depends on RCU_EXPERT
+       select TASKS_TRACE_RCU
+       default n
        help
          This option enables a task-based RCU implementation that uses
          explicit rcu_read_lock_trace() read-side markers, and allows
-         these readers to appear in the idle loop as well as on the CPU
-         hotplug code paths.  It can force IPIs on online CPUs, including
-         idle ones, so use with caution.
+         these readers to appear in the idle loop as well as on the
+         CPU hotplug code paths.  It can force IPIs on online CPUs,
+         including idle ones, so use with caution.  Not for manual
+         selection in most cases.
+
+config TASKS_TRACE_RCU
+       bool
+       default n
+       select IRQ_WORK
 
 config RCU_STALL_COMMON
        def_bool TREE_RCU
@@ -227,7 +235,7 @@ config RCU_NOCB_CPU
 
 config TASKS_TRACE_RCU_READ_MB
        bool "Tasks Trace RCU readers use memory barriers in user and idle"
-       depends on RCU_EXPERT
+       depends on RCU_EXPERT && TASKS_TRACE_RCU
        default PREEMPT_RT || NR_CPUS < 8
        help
          Use this option to further reduce the number of IPIs sent

diff --git a/kernel/rcu/Kconfig.debug b/kernel/rcu/Kconfig.debug
index 4fd64999300fc229bea06793861adae6042a697b..d7f4bb1c49795b2c8a7cc10e07606fc287833702 100644 (file)
--- a/kernel/rcu/Kconfig.debug
+++ b/kernel/rcu/Kconfig.debug
@@ -49,7 +49,6 @@ config RCU_TORTURE_TEST
        select SRCU
        select TASKS_RCU
        select TASKS_RUDE_RCU
-       select TASKS_TRACE_RCU
        default n
        help
          This option provides a kernel module that runs torture tests

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 55d049c39608f581bc8157fc0fbb6264c2ba0bde..7dd3e14ec90720565804ebd59882fa56d58421de 100644 (file)
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -737,6 +737,48 @@ static struct rcu_torture_ops busted_srcud_ops = {
        .name           = "busted_srcud"
 };
 
+/*
+ * 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.
  */
@@ -780,48 +822,6 @@ static struct rcu_torture_ops tasks_ops = {
        .name           = "tasks"
 };
 
-/*
- * 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))

diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TRACE01 b/tools/testing/selftests/rcutorture/configs/rcu/TRACE01
index e4d74e5fc1d09bae1622a4f966458f253d14c034..0f5605ed1e484fd183d9be180a3d44cfcd079c3e 100644 (file)
--- a/tools/testing/selftests/rcutorture/configs/rcu/TRACE01
+++ b/tools/testing/selftests/rcutorture/configs/rcu/TRACE01
@@ -7,5 +7,7 @@ CONFIG_PREEMPT=n
 CONFIG_DEBUG_LOCK_ALLOC=n
 CONFIG_PROVE_LOCKING=n
 #CHECK#CONFIG_PROVE_RCU=n
+CONFIG_FORCE_TASKS_TRACE_RCU=y
+#CHECK#CONFIG_TASKS_TRACE_RCU=y
 CONFIG_TASKS_TRACE_RCU_READ_MB=y
 CONFIG_RCU_EXPERT=y

diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TRACE02 b/tools/testing/selftests/rcutorture/configs/rcu/TRACE02
index 77541eeb4e9fa1c6f8a955609c73b6ef4068fd24..093ea6e8e65cdf924ecaea7abb69f12d510ec4e8 100644 (file)
--- a/tools/testing/selftests/rcutorture/configs/rcu/TRACE02
+++ b/tools/testing/selftests/rcutorture/configs/rcu/TRACE02
@@ -7,5 +7,7 @@ CONFIG_PREEMPT=y
 CONFIG_DEBUG_LOCK_ALLOC=y
 CONFIG_PROVE_LOCKING=y
 #CHECK#CONFIG_PROVE_RCU=y
+CONFIG_FORCE_TASKS_TRACE_RCU=y
+#CHECK#CONFIG_TASKS_TRACE_RCU=y
 CONFIG_TASKS_TRACE_RCU_READ_MB=n
 CONFIG_RCU_EXPERT=y