Re: [PATCH]CPU hotplug breaks wake_up_new_task

[Srivatsa Vaddagiri]

On Tue, May 31, 2005 at 07:46:13PM +1000, Nick Piggin wrote:
> And this patch will break balance-on-fork.

Right :-)

> How about conditionally setting task_cpu if the task's current
> CPU is offline?

Something like this?

--- kernel/fork.c.org	2005-05-31 14:57:15.000000000 +0530
+++ kernel/fork.c	2005-05-31 16:06:41.000000000 +0530
@@ -1024,7 +1024,8 @@ static task_t *copy_process(unsigned lon
 	 * parent's CPU). This avoids alot of nasty races.
 	 */
 	p->cpus_allowed = current->cpus_allowed;
-	if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed)))
+	if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed) ||
+		     !cpu_online(task_cpu(p))))
 		set_task_cpu(p, smp_processor_id());
 
 	/*



-- 


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