[CPU Hotplug PATCH] Restore Idle task's priority during CPU_DEAD notification

[Srivatsa Vaddagiri <vatsa@in.ibm.com>]

Linus,
	Patch below (against 2.6.7-rc1) fixes a CPU Hotplug problem wherein
idle task's "->prio" value is not restored to MAX_PRIO during CPU_DEAD 
handling. Without this patch, once a CPU is offlined and then later onlined, it 
becomes "more or less" useless (does not run any task other than its idle task!)
Please apply.


---

 linux-2.6.7-rc1-vatsa/kernel/sched.c |    1 +
 1 files changed, 1 insertion(+)

diff -puN kernel/sched.c~restore_idle_prio kernel/sched.c
--- linux-2.6.7-rc1/kernel/sched.c~restore_idle_prio	2004-05-25 17:04:19.000000000 +0530
+++ linux-2.6.7-rc1-vatsa/kernel/sched.c	2004-05-25 17:04:34.000000000 +0530
@@ -3569,6 +3569,7 @@ static int migration_call(struct notifie
 		rq = task_rq_lock(rq->idle, &flags);
 		deactivate_task(rq->idle, rq);
 		__setscheduler(rq->idle, SCHED_NORMAL, MAX_PRIO);
+		rq->idle->prio = MAX_PRIO;
 		task_rq_unlock(rq, &flags);
  		BUG_ON(rq->nr_running != 0);
 

_
On Wed, May 26, 2004 at 12:06:46PM +1000, Rusty Russell wrote:
> On Wed, 2004-05-26 at 02:35, Raj, Ashok wrote:
> > Thanks Vatsa...
> > 
> > It seems to work right now....
> 
> It seems obviously correct and harmless to me.  As it also fixes a
> problem, I'd say this should go to Linus & Andrew ASAP.
> 
> Thanks!
> Rusty.
> -- 
> Anyone who quotes me in their signature is an idiot -- Rusty Russell
> 

-- 


Thanks and Regards,
Srivatsa Vaddagiri,
Linux Technology Center,
IBM Software Labs,
Bangalore, INDIA - 560017