[PATCH] kthread: set kthread state to TASK_IDLE.

[PATCH] kthread: set kthread state to TASK_IDLE.

[liyueyi]

From: liyueyi <liyueyi@xiaomi.com>

Currently kthread() sleeps in TASK_UNINTERRUPTIBLE state waiting
for the first wakeup, it may be detected by DETECT_HUNG_TASK if
the first wakeup is coming later. Since kernel has introduced
TASK_IDLE, change kthread state to TASK_IDLE.

Signed-off-by: liyueyi <liyueyi@xiaomi.com>
---
 kernel/kthread.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/kthread.c b/kernel/kthread.c
index b262f470..f841419 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -243,7 +243,7 @@ static int kthread(void *_create)
 	current->vfork_done = &self->exited;
 
 	/* OK, tell user we're spawned, wait for stop or wakeup */
-	__set_current_state(TASK_UNINTERRUPTIBLE);
+	__set_current_state(TASK_IDLE);
 	create->result = current;
 	complete(done);
 	schedule();
@@ -415,7 +415,7 @@ static void __kthread_bind(struct task_struct *p, unsigned int cpu, long state)
 
 void kthread_bind_mask(struct task_struct *p, const struct cpumask *mask)
 {
-	__kthread_bind_mask(p, mask, TASK_UNINTERRUPTIBLE);
+	__kthread_bind_mask(p, mask, TASK_IDLE);
 }
 
 /**
@@ -429,7 +429,7 @@ void kthread_bind_mask(struct task_struct *p, const struct cpumask *mask)
  */
 void kthread_bind(struct task_struct *p, unsigned int cpu)
 {
-	__kthread_bind(p, cpu, TASK_UNINTERRUPTIBLE);
+	__kthread_bind(p, cpu, TASK_IDLE);
 }
 EXPORT_SYMBOL(kthread_bind);
 
-- 
2.7.4

Re: [PATCH] kthread: set kthread state to TASK_IDLE.

[Peter Zijlstra]

On Wed, Apr 01, 2020 at 02:52:15PM +0800, liyueyi wrote:
> From: liyueyi <liyueyi@xiaomi.com>
> 
> Currently kthread() sleeps in TASK_UNINTERRUPTIBLE state waiting
> for the first wakeup, it may be detected by DETECT_HUNG_TASK if
> the first wakeup is coming later. Since kernel has introduced
> TASK_IDLE, change kthread state to TASK_IDLE.

How the heck can that ever happen anyway? Is this some virt
brain-damage?

And how is it not a real problem when it takes this long? 

Re: [PATCH] kthread: set kthread state to TASK_IDLE.

[Peter Zijlstra]

A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?

On Wed, Apr 01, 2020 at 10:40:28AM +0000, Li Yueyi wrote:
> I create a kthread to do some work will trigger system restart, i don`t wake it up immediately but wakeup it in a HW irq handler.
> So this kthread sleeps in TASK_UNINTERRUPTIBLE state until the HW irq coming up.
> 
> Did i do something wrong?
> Should i wake it up immediately and then call wait_event_xxxx function to sleep it?

This!

Re: [PATCH] kthread: set kthread state to TASK_IDLE.

[Yueyi Li]

On 2020/4/1 19:12, Peter Zijlstra wrote:
> 
> A: Because it messes up the order in which people normally read text.
> Q: Why is top-posting such a bad thing?
> A: Top-posting.
> Q: What is the most annoying thing in e-mail?
> 
> On Wed, Apr 01, 2020 at 10:40:28AM +0000, Li Yueyi wrote:
>> I create a kthread to do some work will trigger system restart, i don`t wake it up immediately but wakeup it in a HW irq handler.
>> So this kthread sleeps in TASK_UNINTERRUPTIBLE state until the HW irq coming up.
>>
>> Did i do something wrong?
>> Should i wake it up immediately and then call wait_event_xxxx function to sleep it?
> 
> This!
> Oh~, Sorry about top-posting and....thanks for your answer!