blob: 4b0927b0a3ad44ef3b426c5c5dfe4ac45da0831b (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
|
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Tue, 26 Feb 2019 12:31:10 +0100
Subject: [PATCH 184/353] hrtimer: cpu_chill(): save task state in
->saved_state()
Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=0b619882e45a08ee21433ecd2b74d06981e22414
In the previous change I saved the current task state on stack. This was
bad because while the task is scheduled-out it might receive a wake-up.
The wake up changes the task state and we must not destroy it.
Save the task-state in ->saved_state under a PI-lock to unsure that
state changes during are not missed while the task temporary scheduled
out.
Reported-by: Mike Galbraith <efault@gmx.de>
Tested-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
kernel/time/hrtimer.c | 18 +++++++++++++-----
1 file changed, 13 insertions(+), 5 deletions(-)
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index aa208a350a3b..1992f107599e 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1969,20 +1969,28 @@ COMPAT_SYSCALL_DEFINE2(nanosleep, struct compat_timespec __user *, rqtp,
*/
void cpu_chill(void)
{
- ktime_t chill_time;
unsigned int freeze_flag = current->flags & PF_NOFREEZE;
- long saved_state;
+ struct task_struct *self = current;
+ ktime_t chill_time;
- saved_state = current->state;
- chill_time = ktime_set(0, NSEC_PER_MSEC);
+ raw_spin_lock_irq(&self->pi_lock);
+ self->saved_state = self->state;
__set_current_state_no_track(TASK_UNINTERRUPTIBLE);
+ raw_spin_unlock_irq(&self->pi_lock);
+
+ chill_time = ktime_set(0, NSEC_PER_MSEC);
+
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);
+
+ raw_spin_lock_irq(&self->pi_lock);
+ __set_current_state_no_track(self->saved_state);
+ self->saved_state = TASK_RUNNING;
+ raw_spin_unlock_irq(&self->pi_lock);
}
EXPORT_SYMBOL(cpu_chill);
#endif
|
