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From f5a443f1a8355f1e2aca72d20e931d136b979ac9 Mon Sep 17 00:00:00 2001
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Tue, 19 Feb 2019 16:59:15 +0100
Subject: [PATCH 183/347] hrtimer: Don't lose state in cpu_chill()
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.246-rt110.tar.xz
In cpu_chill() the state is set to TASK_UNINTERRUPTIBLE and a timer is
programmed. On return the state is always TASK_RUNNING which means we
lose the state if it was something other than RUNNING. Also
set_current_state() sets ->task_state_change to within cpu_chill() which
is not expected.
Save the task state on entry and restore it on return. Simply set the
state in order to avoid updating ->task_state_change.
Cc: stable-rt@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
kernel/time/hrtimer.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 0b94f54453ef..96e505abf939 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1969,15 +1969,18 @@ void cpu_chill(void)
{
ktime_t chill_time;
unsigned int freeze_flag = current->flags & PF_NOFREEZE;
+ long saved_state;
+ saved_state = current->state;
chill_time = ktime_set(0, NSEC_PER_MSEC);
- set_current_state(TASK_UNINTERRUPTIBLE);
+ __set_current_state_no_track(TASK_UNINTERRUPTIBLE);
current->flags |= PF_NOFREEZE;
sleeping_lock_inc();
schedule_hrtimeout(&chill_time, HRTIMER_MODE_REL_HARD);
sleeping_lock_dec();
if (!freeze_flag)
current->flags &= ~PF_NOFREEZE;
+ __set_current_state_no_track(saved_state);
}
EXPORT_SYMBOL(cpu_chill);
#endif
--
2.36.1
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