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authorUladzislau Rezki (Sony) <urezki@gmail.com>2020-12-09 21:27:31 +0100
committerPaul E. McKenney <paulmck@kernel.org>2020-12-14 15:31:13 -0800
commit1b04fa9900263b4e217ca2509fd778b32c2b4eb2 (patch)
tree9d5e4a413b1e641955514dc16b4b2ba4a7924c5e
parent0477e92881850d44910a7e94fc2c46f96faa131f (diff)
rcu-tasks: Move RCU-tasks initialization to before early_initcall()
PowerPC testing encountered boot failures due to RCU Tasks not being fully initialized until core_initcall() time. This commit therefore initializes RCU Tasks (along with Rude RCU and RCU Tasks Trace) just before early_initcall() time, thus allowing waiting on RCU Tasks grace periods from early_initcall() handlers. Link: https://lore.kernel.org/rcu/87eekfh80a.fsf@dja-thinkpad.axtens.net/ Fixes: 36dadef23fcc ("kprobes: Init kprobes in early_initcall") Tested-by: Daniel Axtens <dja@axtens.net> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
-rw-r--r--include/linux/rcupdate.h6
-rw-r--r--init/main.c1
-rw-r--r--kernel/rcu/tasks.h25
3 files changed, 28 insertions, 4 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 6cdd0152c253..5c119d6cecf1 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -86,6 +86,12 @@ void rcu_sched_clock_irq(int user);
void rcu_report_dead(unsigned int cpu);
void rcutree_migrate_callbacks(int cpu);
+#ifdef CONFIG_TASKS_RCU_GENERIC
+void rcu_init_tasks_generic(void);
+#else
+static inline void rcu_init_tasks_generic(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 32b2a8affafd..9d964511fe0c 100644
--- a/init/main.c
+++ b/init/main.c
@@ -1512,6 +1512,7 @@ static noinline void __init kernel_init_freeable(void)
init_mm_internals();
+ rcu_init_tasks_generic();
do_pre_smp_initcalls();
lockup_detector_init();
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index d5d9f2d03e8a..73bbe792fe1e 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -241,7 +241,7 @@ static int __noreturn rcu_tasks_kthread(void *arg)
}
}
-/* Spawn RCU-tasks grace-period kthread, e.g., at core_initcall() time. */
+/* Spawn RCU-tasks grace-period kthread. */
static void __init rcu_spawn_tasks_kthread_generic(struct rcu_tasks *rtp)
{
struct task_struct *t;
@@ -569,7 +569,6 @@ static int __init rcu_spawn_tasks_kthread(void)
rcu_spawn_tasks_kthread_generic(&rcu_tasks);
return 0;
}
-core_initcall(rcu_spawn_tasks_kthread);
#ifndef CONFIG_TINY_RCU
static void show_rcu_tasks_classic_gp_kthread(void)
@@ -697,7 +696,6 @@ static int __init rcu_spawn_tasks_rude_kthread(void)
rcu_spawn_tasks_kthread_generic(&rcu_tasks_rude);
return 0;
}
-core_initcall(rcu_spawn_tasks_rude_kthread);
#ifndef CONFIG_TINY_RCU
static void show_rcu_tasks_rude_gp_kthread(void)
@@ -975,6 +973,11 @@ static void rcu_tasks_trace_pregp_step(void)
static void rcu_tasks_trace_pertask(struct task_struct *t,
struct list_head *hop)
{
+ // During early boot when there is only the one boot CPU, there
+ // is no idle task for the other CPUs. Just return.
+ if (unlikely(t == NULL))
+ return;
+
WRITE_ONCE(t->trc_reader_special.b.need_qs, false);
WRITE_ONCE(t->trc_reader_checked, false);
t->trc_ipi_to_cpu = -1;
@@ -1200,7 +1203,6 @@ static int __init rcu_spawn_tasks_trace_kthread(void)
rcu_spawn_tasks_kthread_generic(&rcu_tasks_trace);
return 0;
}
-core_initcall(rcu_spawn_tasks_trace_kthread);
#ifndef CONFIG_TINY_RCU
static void show_rcu_tasks_trace_gp_kthread(void)
@@ -1229,6 +1231,21 @@ void show_rcu_tasks_gp_kthreads(void)
}
#endif /* #ifndef CONFIG_TINY_RCU */
+void __init rcu_init_tasks_generic(void)
+{
+#ifdef CONFIG_TASKS_RCU
+ rcu_spawn_tasks_kthread();
+#endif
+
+#ifdef CONFIG_TASKS_RUDE_RCU
+ rcu_spawn_tasks_rude_kthread();
+#endif
+
+#ifdef CONFIG_TASKS_TRACE_RCU
+ rcu_spawn_tasks_trace_kthread();
+#endif
+}
+
#else /* #ifdef CONFIG_TASKS_RCU_GENERIC */
static inline void rcu_tasks_bootup_oddness(void) {}
void show_rcu_tasks_gp_kthreads(void) {}

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