Re: [PATCH] modules fix incorrect percpu usage

[Tejun Heo]

On 03/31/2010 11:03 AM, Steven Rostedt wrote:
> I don't know. A possible "NULL pointer dereference" seems to me to be a
> pretty big user visible impact.
> 
> I guess the question is, what's the risk of adding this change?

AFAICS, the risk is fairly low.  per_cpu_ptr(pcpudest, cpu) is
SHIFT_PERCPU_PTR((ptr), per_cpu_offset((cpu))) which is just a fancy
way of saying "typeof(ptr)((unsigned long)(ptr) + per_cpu_offset(cpu))"
with enough obfuscation to prevent gcc from optimizing it incorrectly.

Thanks.

-- 
tejun
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