Re: [PATCH] percpu: add optimized generic percpu accessors

[Mark Lord]

Andrew Morton wrote:
> On Thu, 15 Jan 2009 19:02:59 +0100 Ingo Molnar <mingo@xxxxxxx> wrote:
>
> > * Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
..
> > > I wonder if the preempt_disable()/preempt_enable() in here actually
> > > does anything useful on any architecture.
> > Provides "this is IRQ safe"
>
> ?
>
> > and "this is preempt safe" semantics.
>
> Of course.  But do any architectures actually _need_ that for a single read?
..

If the target is unaligned, then RISC architectures will need protection there.
If we can guarantee correct memory alignment of the target, then no / none.

Cheers
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