lkml.org 
[lkml]   [2019]   [Feb]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH RT 4/2] hrtimer: Don't lose state in cpu_chill()
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 851b2134e77f4..6f2736ec4b8ef 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1902,15 +1902,18 @@ 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
--
2.20.1
\
 
 \ /
  Last update: 2019-02-19 17:09    [W:0.045 / U:3.596 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site