[PATCH v4 tip/core/rcu 36/38] rcu-tasks: Allow standalone use of TASKS_{TRACE_,}RCU

paulmck
2020-04-15T18:20:49Z

This commit allows TASKS_TRACE_RCU to be used independently of TASKS_RCU
and vice versa.

[ paulmck: Fix conditional compilation per kbuild test robot feedback. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/rcu/tasks.h | 54 ++++++++++++++++++++++++++++++------------------------
1 file changed, 30 insertions(+), 24 deletions(-)

diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index e600d29..234847f 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -244,27 +244,6 @@ static void __init rcu_spawn_tasks_kthread_generic(struct rcu_tasks *rtp)
smp_mb(); /* Ensure others see full kthread. */
}

-/* Do the srcu_read_lock() for the above synchronize_srcu(). */
-void exit_tasks_rcu_start(void) __acquires(&tasks_rcu_exit_srcu)
-{
- preempt_disable();
- current->rcu_tasks_idx = __srcu_read_lock(&tasks_rcu_exit_srcu);
- preempt_enable();
-}
-
-static void exit_tasks_rcu_finish_trace(struct task_struct *t);
-
-/* Do the srcu_read_unlock() for the above synchronize_srcu(). */
-void exit_tasks_rcu_finish(void) __releases(&tasks_rcu_exit_srcu)
-{
- struct task_struct *t = current;
-
- preempt_disable();
- __srcu_read_unlock(&tasks_rcu_exit_srcu, t->rcu_tasks_idx);
- preempt_enable();
- exit_tasks_rcu_finish_trace(t);
-}
-
#ifndef CONFIG_TINY_RCU

/*
@@ -303,7 +282,9 @@ static void show_rcu_tasks_generic_gp_kthread(struct rcu_tasks *rtp, char *s)
s);
}

-#ifdef CONFIG_TASKS_RCU
+static void exit_tasks_rcu_finish_trace(struct task_struct *t);
+
+#if defined(CONFIG_TASKS_RCU) || defined(CONFIG_TASKS_TRACE_RCU)

////////////////////////////////////////////////////////////////////////
//
@@ -374,6 +355,10 @@ static void rcu_tasks_wait_gp(struct rcu_tasks *rtp)
rtp->postgp_func(rtp);
}

+#endif /* #if defined(CONFIG_TASKS_RCU) || defined(CONFIG_TASKS_TRACE_RCU) */
+
+#ifdef CONFIG_TASKS_RCU
+
////////////////////////////////////////////////////////////////////////
//
// Simple variant of RCU whose quiescent states are voluntary context
@@ -577,8 +562,29 @@ static void show_rcu_tasks_classic_gp_kthread(void)
show_rcu_tasks_generic_gp_kthread(&rcu_tasks, "");
}

+/* Do the srcu_read_lock() for the above synchronize_srcu(). */
+void exit_tasks_rcu_start(void) __acquires(&tasks_rcu_exit_srcu)
+{
+ preempt_disable();
+ current->rcu_tasks_idx = __srcu_read_lock(&tasks_rcu_exit_srcu);
+ preempt_enable();
+}
+
+/* Do the srcu_read_unlock() for the above synchronize_srcu(). */
+void exit_tasks_rcu_finish(void) __releases(&tasks_rcu_exit_srcu)
+{
+ struct task_struct *t = current;
+
+ preempt_disable();
+ __srcu_read_unlock(&tasks_rcu_exit_srcu, t->rcu_tasks_idx);
+ preempt_enable();
+ exit_tasks_rcu_finish_trace(t);
+}
+
#else /* #ifdef CONFIG_TASKS_RCU */
static void show_rcu_tasks_classic_gp_kthread(void) { }
+void exit_tasks_rcu_start(void) { }
+void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); }
#endif /* #else #ifdef CONFIG_TASKS_RCU */

#ifdef CONFIG_TASKS_RUDE_RCU
@@ -1071,7 +1077,7 @@ static void rcu_tasks_trace_postgp(struct rcu_tasks *rtp)
}

/* Report any needed quiescent state for this exiting task. */
-void exit_tasks_rcu_finish_trace(struct task_struct *t)
+static void exit_tasks_rcu_finish_trace(struct task_struct *t)
{
WRITE_ONCE(t->trc_reader_checked, true);
WARN_ON_ONCE(t->trc_reader_nesting);
@@ -1166,7 +1172,7 @@ static void show_rcu_tasks_trace_gp_kthread(void)
}

#else /* #ifdef CONFIG_TASKS_TRACE_RCU */
-void exit_tasks_rcu_finish_trace(struct task_struct *t) { }
+static void exit_tasks_rcu_finish_trace(struct task_struct *t) { }
static inline void show_rcu_tasks_trace_gp_kthread(void) {}
#endif /* #else #ifdef CONFIG_TASKS_TRACE_RCU */

--
2.9.5