Re: [RFC][PATCH 4/5] printk: Have wake_up_klogd() use__this_cpu_write()

[Peter Zijlstra]

On Tue, 2011-09-20 at 09:54 -0500, Christoph Lameter wrote:
> On Mon, 19 Sep 2011, Steven Rostedt wrote:
> 
> > Note, just because something is always in a location that preemption is
> > disabled, does not mean it should use the __this_cpu*() variants.
> 
> Why not? If preemption is disabled then the process cannot be migrated to
> another processor. And thus doing the address calculations and operations
> on variables step by step is okay.
> 
> > Because if things change, it may become a problem later on.
> 
> What things may change? Someone calls the function with preemption
> enabled? 

Yes, also, for !x86 you get a redundant preempt_disable/enable pair.


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