Re: frequent lockups in 3.18rc4

From: Linus Torvalds
Date: Sat Dec 13 2014 - 20:35:33 EST


On Sat, Dec 13, 2014 at 4:33 PM, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote:
>
> So does SMP - this_cpu_dec() relies on preemption being disabled.

No. really. It very much does not. Not on x86, not elsewhere. It's
part of the whole point of "this_cpu_p()". They are preemption and
interrupt safe.

It's the "__this_cpu_op()" ones that need external protection.

Linus
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