The RCU-sefltest expects tthe timer_list timer to be working. This isn't
the case on PREEMPT_RT at this point because it requires that ksoftirqd
is up and running.
There is no known requirement that synchronize_rcu() works at this
point.
Delay RCU-selftests until ksoftirqd is up and running.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
Paul, I don't mean to be rude or anything by saying that "There is no
requirement…". If my memory serves me well here (and there is no
guarantee for that) then synchronize_rcu() was required that early by
kprobes or jump labels and this requirement was lifted by the time we
discussed this. I have no idea how this discussion back then ended but
as of v5.17-rc6 that timer is still required to function in order for
the system to make progress at boot time.
include/linux/rcupdate.h | 6 ++++++
init/main.c | 1 +
kernel/rcu/tasks.h | 10 +++-------
3 files changed, 10 insertions(+), 7 deletions(-)
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 88b42eb464068..2fb1a48ca9272 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -95,6 +95,12 @@ void rcu_init_tasks_generic(void);
static inline void rcu_init_tasks_generic(void) { }
#endif
+#if defined(CONFIG_PROVE_RCU) && defined(CONFIG_TASKS_RCU_GENERIC)
+void rcu_tasks_initiate_self_tests(void);
+#else
+static inline void rcu_tasks_initiate_self_tests(void) {}
+#endif
+
#ifdef CONFIG_RCU_STALL_COMMON
void rcu_sysrq_start(void);
void rcu_sysrq_end(void);
diff --git a/init/main.c b/init/main.c
index 65fa2e41a9c09..cfc45e47b9ca4 100644
--- a/init/main.c
+++ b/init/main.c
@@ -1600,6 +1600,7 @@ static noinline void __init kernel_init_freeable(void)
rcu_init_tasks_generic();
do_pre_smp_initcalls();
+ rcu_tasks_initiate_self_tests();
lockup_detector_init();
smp_init();
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index d64f0b1d8cd3b..215c2c0f6c184 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -1659,9 +1659,10 @@ static void test_rcu_tasks_callback(struct rcu_head *rhp)
pr_info("Callback from %s invoked.\n", rttd->name);
rttd->notrun = true;
+ WARN_ON(1);
}
-static void rcu_tasks_initiate_self_tests(void)
+void rcu_tasks_initiate_self_tests(void)
{
pr_info("Running RCU-tasks wait API self tests\n");
#ifdef CONFIG_TASKS_RCU
@@ -1698,9 +1699,7 @@ static int rcu_tasks_verify_self_tests(void)
return ret;
}
late_initcall(rcu_tasks_verify_self_tests);
-#else /* #ifdef CONFIG_PROVE_RCU */
-static void rcu_tasks_initiate_self_tests(void) { }
-#endif /* #else #ifdef CONFIG_PROVE_RCU */
+#endif /* #ifdef CONFIG_PROVE_RCU */
void __init rcu_init_tasks_generic(void)
{
@@ -1715,9 +1714,6 @@ void __init rcu_init_tasks_generic(void)
#ifdef CONFIG_TASKS_TRACE_RCU
rcu_spawn_tasks_trace_kthread();
#endif
-
- // Run the self-tests.
- rcu_tasks_initiate_self_tests();
}
#else /* #ifdef CONFIG_TASKS_RCU_GENERIC */
--
2.35.1
