From a23f6209aefae9236eef4f9932fe1bcd4ed35d52 Mon Sep 17 00:00:00 2001
From: Alexander Boettcher <alexander.boettcher@genode-labs.com>
Date: Fri, 17 Jun 2022 15:14:25 +0200
Subject: [PATCH] lx_emul: stop ticking in idle task

Fixes #4540
---
 repos/dde_linux/src/include/lx_emul/task.h      |  2 ++
 repos/dde_linux/src/include/lx_kit/scheduler.h  |  2 ++
 .../src/lib/lx_emul/shadow/kernel/sched/core.c  |  1 +
 .../src/lib/lx_emul/shadow/kernel/softirq.c     |  1 +
 .../src/lib/lx_emul/spec/arm/irqchip.c          |  4 ++++
 .../src/lib/lx_emul/spec/x86/irqchip.c          |  4 ++++
 repos/dde_linux/src/lib/lx_emul/start.c         |  8 ++++++++
 repos/dde_linux/src/lib/lx_emul/task.cc         |  8 ++++++++
 repos/dde_linux/src/lib/lx_kit/scheduler.cc     | 17 +++++++++++++++++
 9 files changed, 47 insertions(+)

diff --git a/repos/dde_linux/src/include/lx_emul/task.h b/repos/dde_linux/src/include/lx_emul/task.h
index 6cc629e857..487c8eed39 100644
--- a/repos/dde_linux/src/include/lx_emul/task.h
+++ b/repos/dde_linux/src/include/lx_emul/task.h
@@ -44,6 +44,8 @@ void lx_emul_task_name(struct task_struct * task, const char * name);
 
 void *lx_emul_task_stack(struct task_struct const * task);
 
+char lx_emul_task_another_runnable(void);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/repos/dde_linux/src/include/lx_kit/scheduler.h b/repos/dde_linux/src/include/lx_kit/scheduler.h
index a80aa580d4..26e9b0c4ac 100644
--- a/repos/dde_linux/src/include/lx_kit/scheduler.h
+++ b/repos/dde_linux/src/include/lx_kit/scheduler.h
@@ -45,6 +45,8 @@ class Lx_kit::Scheduler
 		void unblock_irq_handler();
 		void unblock_time_handler();
 
+		bool another_runnable(Task *);
+
 		Task & task(void * t);
 
 		template <typename FN>
diff --git a/repos/dde_linux/src/lib/lx_emul/shadow/kernel/sched/core.c b/repos/dde_linux/src/lib/lx_emul/shadow/kernel/sched/core.c
index 988268294d..5f81b1feba 100644
--- a/repos/dde_linux/src/lib/lx_emul/shadow/kernel/sched/core.c
+++ b/repos/dde_linux/src/lib/lx_emul/shadow/kernel/sched/core.c
@@ -64,6 +64,7 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
 		lx_emul_task_unblock(p);
 
 	p->__state = TASK_RUNNING;
+
 	return 1;
 }
 
diff --git a/repos/dde_linux/src/lib/lx_emul/shadow/kernel/softirq.c b/repos/dde_linux/src/lib/lx_emul/shadow/kernel/softirq.c
index ba80a41d1c..542f1a8110 100644
--- a/repos/dde_linux/src/lib/lx_emul/shadow/kernel/softirq.c
+++ b/repos/dde_linux/src/lib/lx_emul/shadow/kernel/softirq.c
@@ -13,6 +13,7 @@
 
 #include <linux/interrupt.h>
 #include <linux/bottom_half.h>
+#include <linux/tick.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/irq.h>
diff --git a/repos/dde_linux/src/lib/lx_emul/spec/arm/irqchip.c b/repos/dde_linux/src/lib/lx_emul/spec/arm/irqchip.c
index 9e5cb9f24d..862790614c 100644
--- a/repos/dde_linux/src/lib/lx_emul/spec/arm/irqchip.c
+++ b/repos/dde_linux/src/lib/lx_emul/spec/arm/irqchip.c
@@ -17,6 +17,7 @@
 #include <linux/of_irq.h>
 #include <linux/slab.h>
 #include <linux/irqchip.h>
+#include <linux/tick.h>
 #include <../kernel/irq/internals.h>
 
 static int dde_irq_set_wake(struct irq_data *d, unsigned int on)
@@ -174,6 +175,9 @@ int lx_emul_irq_task_function(void * data)
 		if (!dde_irq_domain)
 			continue;
 
+		/* check restarting ticking which may stopped in idle task */
+		tick_nohz_idle_restart_tick();
+
 		irq_enter();
 
 		irq = irq_find_mapping(dde_irq_domain, lx_emul_irq_last());
diff --git a/repos/dde_linux/src/lib/lx_emul/spec/x86/irqchip.c b/repos/dde_linux/src/lib/lx_emul/spec/x86/irqchip.c
index fd3cb9e570..707317e849 100644
--- a/repos/dde_linux/src/lib/lx_emul/spec/x86/irqchip.c
+++ b/repos/dde_linux/src/lib/lx_emul/spec/x86/irqchip.c
@@ -15,6 +15,7 @@
 #include <lx_emul/irq.h>
 #include <linux/irq.h>
 #include <linux/irqchip.h>
+#include <linux/tick.h>
 #include <../kernel/irq/internals.h>
 
 
@@ -46,6 +47,9 @@ int lx_emul_irq_task_function(void * data)
 	for (;;) {
 		lx_emul_task_schedule(true);
 
+		/* check restarting ticking which may stopped in idle task */
+		tick_nohz_idle_restart_tick();
+
 		irq_enter();
 
 		irq = lx_emul_irq_last();
diff --git a/repos/dde_linux/src/lib/lx_emul/start.c b/repos/dde_linux/src/lib/lx_emul/start.c
index ec9469edca..ebad304827 100644
--- a/repos/dde_linux/src/lib/lx_emul/start.c
+++ b/repos/dde_linux/src/lib/lx_emul/start.c
@@ -73,8 +73,16 @@ static void timer_loop(void)
 {
 	for (;;) {
 		tick_nohz_idle_enter();
+
+		if (!lx_emul_task_another_runnable())
+			tick_nohz_idle_stop_tick();
+
 		lx_emul_task_schedule(true);
 		lx_emul_time_handle();
+
+		/* check restarting ticking */
+		tick_nohz_idle_restart_tick();
+
 		tick_nohz_idle_exit();
 	}
 }
diff --git a/repos/dde_linux/src/lib/lx_emul/task.cc b/repos/dde_linux/src/lib/lx_emul/task.cc
index 350d121a27..04ba17b4fb 100644
--- a/repos/dde_linux/src/lib/lx_emul/task.cc
+++ b/repos/dde_linux/src/lib/lx_emul/task.cc
@@ -100,3 +100,11 @@ extern "C" void * lx_emul_task_stack(struct task_struct const * t)
 
 	return ret;
 }
+
+
+extern "C" char lx_emul_task_another_runnable()
+{
+	Lx_kit::Task & task = Lx_kit::env().scheduler.current();
+
+	return Lx_kit::env().scheduler.another_runnable(&task);
+}
diff --git a/repos/dde_linux/src/lib/lx_kit/scheduler.cc b/repos/dde_linux/src/lib/lx_kit/scheduler.cc
index d6182b3ba9..e0ec62e8b5 100644
--- a/repos/dde_linux/src/lib/lx_kit/scheduler.cc
+++ b/repos/dde_linux/src/lib/lx_kit/scheduler.cc
@@ -127,3 +127,20 @@ void Scheduler::schedule()
 	/* clear current as no task is running */
 	_current = nullptr;
 }
+
+
+bool Scheduler::another_runnable(Task * skip)
+{
+	for (Task * t = _present_list.first(); t; t = t->next()) {
+
+		if (!t->runnable())
+			continue;
+
+		if (skip && t == skip)
+			continue;
+
+		return true;
+	};
+
+	return false;
+}