From 14be6e87e43466b20d88e6a12e01cd9cf40d40b1 Mon Sep 17 00:00:00 2001
From: Con Kolivas <kernel@kolivas.org>
Date: Tue, 8 Nov 2016 17:54:56 +1100
Subject: [PATCH] Make freezable timeouts not use the highres timers.

---
 include/linux/freezer.h |  7 +++++--
 kernel/time/timer.c     | 22 +++++++++++++++++-----
 2 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/include/linux/freezer.h b/include/linux/freezer.h
index dd03e83..322395b 100644
--- a/include/linux/freezer.h
+++ b/include/linux/freezer.h
@@ -180,6 +180,8 @@ static inline void freezable_schedule_unsafe(void)
 	freezer_count_unsafe();
 }
 
+extern signed long fschedule_timeout(signed long timeout);
+
 /*
  * Like freezable_schedule_timeout(), but should not block the freezer.  Do not
  * call this with locks held.
@@ -188,7 +190,7 @@ static inline long freezable_schedule_timeout(long timeout)
 {
 	long __retval;
 	freezer_do_not_count();
-	__retval = schedule_timeout(timeout);
+	__retval = fschedule_timeout(timeout);
 	freezer_count();
 	return __retval;
 }
@@ -201,7 +203,8 @@ static inline long freezable_schedule_timeout_interruptible(long timeout)
 {
 	long __retval;
 	freezer_do_not_count();
-	__retval = schedule_timeout_interruptible(timeout);
+	__set_current_state(TASK_INTERRUPTIBLE);
+	__retval = fschedule_timeout(timeout);
 	freezer_count();
 	return __retval;
 }
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 7651d47..0455ab7 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1709,7 +1709,7 @@ static void process_timeout(unsigned long __data)
  *
  * In all cases the return value is guaranteed to be non-negative.
  */
-signed long __sched schedule_timeout(signed long timeout)
+static signed long __schedule_timeout(signed long timeout, bool freezable)
 {
 	struct timer_list timer;
 	unsigned long expire;
@@ -1745,7 +1745,7 @@ signed long __sched schedule_timeout(signed long timeout)
 
 	expire = timeout + jiffies;
 
-	if (timeout == 1 && hrtimer_resolution < NSEC_PER_SEC / HZ) {
+	if (timeout == 1 && !freezable && hrtimer_resolution < NSEC_PER_SEC / HZ) {
 		/*
 		 * Special case 1 as being a request for the minimum timeout
 		 * and use highres timers to timeout after 1ms to workaround
@@ -1769,8 +1769,20 @@ out_timeout:
 out:
 	return timeout < 0 ? 0 : timeout;
 }
+
+signed long __sched schedule_timeout(signed long timeout)
+{
+	return __schedule_timeout(timeout, false);
+}
 EXPORT_SYMBOL(schedule_timeout);
 
+signed long __sched fschedule_timeout(signed long timeout)
+{
+	return __schedule_timeout(timeout, true);
+}
+EXPORT_SYMBOL(fschedule_timeout);
+
+
 /*
  * We can use __set_current_state() here because schedule_timeout() calls
  * schedule() unconditionally.
@@ -1785,14 +1797,14 @@ EXPORT_SYMBOL(schedule_timeout_interruptible);
 signed long __sched schedule_timeout_killable(signed long timeout)
 {
 	__set_current_state(TASK_KILLABLE);
-	return schedule_timeout(timeout);
+	return fschedule_timeout(timeout);
 }
 EXPORT_SYMBOL(schedule_timeout_killable);
 
 signed long __sched schedule_timeout_uninterruptible(signed long timeout)
 {
 	__set_current_state(TASK_UNINTERRUPTIBLE);
-	return schedule_timeout(timeout);
+	return fschedule_timeout(timeout);
 }
 EXPORT_SYMBOL(schedule_timeout_uninterruptible);
 
@@ -1803,7 +1815,7 @@ EXPORT_SYMBOL(schedule_timeout_uninterruptible);
 signed long __sched schedule_timeout_idle(signed long timeout)
 {
 	__set_current_state(TASK_IDLE);
-	return schedule_timeout(timeout);
+	return fschedule_timeout(timeout);
 }
 EXPORT_SYMBOL(schedule_timeout_idle);
 
-- 
2.7.4