rcu-tasks: Code movement to allow more Tasks RCU variants

This commit does nothing but move rcu_tasks_wait_gp() up to a new section
for common code.

Signed-off-by: Paul E. McKenney <[email protected]>

Author: paulmckrcu

kernel/rcu/tasks.h

@@ -211,6 +211,69 @@ static void __init rcu_tasks_bootup_oddness(void)
 
 #ifdef CONFIG_TASKS_RCU
 
+////////////////////////////////////////////////////////////////////////
+//
+// Shared code between task-list-scanning variants of Tasks RCU.
+
+/* Wait for one RCU-tasks grace period. */
+static void rcu_tasks_wait_gp(struct rcu_tasks *rtp)
+{
+	struct task_struct *g, *t;
+	unsigned long lastreport;
+	LIST_HEAD(holdouts);
+	int fract;
+
+	rtp->pregp_func();
+
+	/*
+	 * There were callbacks, so we need to wait for an RCU-tasks
+	 * grace period.  Start off by scanning the task list for tasks
+	 * that are not already voluntarily blocked.  Mark these tasks
+	 * and make a list of them in holdouts.
+	 */
+	rcu_read_lock();
+	for_each_process_thread(g, t)
+		rtp->pertask_func(t, &holdouts);
+	rcu_read_unlock();
+
+	rtp->postscan_func();
+
+	/*
+	 * Each pass through the following loop scans the list of holdout
+	 * tasks, removing any that are no longer holdouts.  When the list
+	 * is empty, we are done.
+	 */
+	lastreport = jiffies;
+
+	/* Start off with HZ/10 wait and slowly back off to 1 HZ wait. */
+	fract = 10;
+
+	for (;;) {
+		bool firstreport;
+		bool needreport;
+		int rtst;
+
+		if (list_empty(&holdouts))
+			break;
+
+		/* Slowly back off waiting for holdouts */
+		schedule_timeout_interruptible(HZ/fract);
+
+		if (fract > 1)
+			fract--;
+
+		rtst = READ_ONCE(rcu_task_stall_timeout);
+		needreport = rtst > 0 && time_after(jiffies, lastreport + rtst);
+		if (needreport)
+			lastreport = jiffies;
+		firstreport = true;
+		WARN_ON(signal_pending(current));
+		rtp->holdouts_func(&holdouts, needreport, &firstreport);
+	}
+
+	rtp->postgp_func();
+}
+
 ////////////////////////////////////////////////////////////////////////
 //
 // Simple variant of RCU whose quiescent states are voluntary context
@@ -333,65 +396,6 @@ static void rcu_tasks_postgp(void)
 	synchronize_rcu();
 }
 
-/* Wait for one RCU-tasks grace period. */
-static void rcu_tasks_wait_gp(struct rcu_tasks *rtp)
-{
-	struct task_struct *g, *t;
-	unsigned long lastreport;
-	LIST_HEAD(holdouts);
-	int fract;
-
-	rtp->pregp_func();
-
-	/*
-	 * There were callbacks, so we need to wait for an RCU-tasks
-	 * grace period.  Start off by scanning the task list for tasks
-	 * that are not already voluntarily blocked.  Mark these tasks
-	 * and make a list of them in holdouts.
-	 */
-	rcu_read_lock();
-	for_each_process_thread(g, t)
-		rtp->pertask_func(t, &holdouts);
-	rcu_read_unlock();
-
-	rtp->postscan_func();
-
-	/*
-	 * Each pass through the following loop scans the list of holdout
-	 * tasks, removing any that are no longer holdouts.  When the list
-	 * is empty, we are done.
-	 */
-	lastreport = jiffies;
-
-	/* Start off with HZ/10 wait and slowly back off to 1 HZ wait. */
-	fract = 10;
-
-	for (;;) {
-		bool firstreport;
-		bool needreport;
-		int rtst;
-
-		if (list_empty(&holdouts))
-			break;
-
-		/* Slowly back off waiting for holdouts */
-		schedule_timeout_interruptible(HZ/fract);
-
-		if (fract > 1)
-			fract--;
-
-		rtst = READ_ONCE(rcu_task_stall_timeout);
-		needreport = rtst > 0 && time_after(jiffies, lastreport + rtst);
-		if (needreport)
-			lastreport = jiffies;
-		firstreport = true;
-		WARN_ON(signal_pending(current));
-		rtp->holdouts_func(&holdouts, needreport, &firstreport);
-	}
-
-	rtp->postgp_func();
-}
-
 void call_rcu_tasks(struct rcu_head *rhp, rcu_callback_t func);
 DEFINE_RCU_TASKS(rcu_tasks, rcu_tasks_wait_gp, call_rcu_tasks, "RCU Tasks");