Subject: Re: [PATCH][RFC] preempt_count corruption across H_CEDE call with CONFIG_PREEMPT on pseries

From: Darren Hart <[email-masked]>
Date: Wed, 04 Aug 2010 06:44:59 -0700

On 07/22/2010 03:25 PM, Benjamin Herrenschmidt wrote:
> On Thu, 2010-07-22 at 11:24 -0700, Darren Hart wrote:
>>
>> 1) How can the preempt_count() get mangled across the H_CEDE hcall?
>> 2) Should we call preempt_enable() in cpu_idle() prior to cpu_die() ?
>
> The preempt count is on the thread info at the bottom of the stack.
>
> Can you check the stack pointers ?

Hi Ben, sorry if I didn't get back to you on this already. I checked the 
stack pointer before and after the cede call and they match.

-- 
Darren Hart
IBM Linux Technology Center
Real-Time Linux Team