lkml.org 
[lkml]   [2012]   [Dec]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC PATCH v3 7/9] yield_to(), cpu-hotplug: Prevent offlining of other CPUs properly
On 12/07, Srivatsa S. Bhat wrote:
>
> Once stop_machine() is gone from the CPU offline path, we won't be able to
> depend on local_irq_save() to prevent CPUs from going offline from under us.

OK, I guess we need to avoid resched_task()->smp_send_reschedule()
after __cpu_disable() and before migrate_tasks().

But, whatever problem we have,

> Use the get/put_online_cpus_atomic() APIs to prevent CPUs from going offline,
> while invoking from atomic context.

it should be solved, so...

> - if (preempt && rq != p_rq)
> + if (preempt && rq != p_rq && cpu_online(task_cpu(p)))

Why do we need this change?

Afaics, you could add BUG_ON(!cpu_online(...)) instead?

I am just curious.

Oleg.



\
 
 \ /
  Last update: 2012-12-09 21:21    [W:0.098 / U:0.144 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site