Re: [PATCH v6 15/17] static_call: Allow early init

[Peter Zijlstra]

On Fri, Jul 10, 2020 at 09:14:26PM -0400, Steven Rostedt wrote:
> On Fri, 10 Jul 2020 15:38:46 +0200
> Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> 
> > In order to use static_call() to wire up x86_pmu, we need to
> > initialize earlier; copy some of the tricks from jump_label to enable
> > this.
> > 
> > Primarily we overload key->next to store a sites pointer when there
> > are no modules, this avoids having to use kmalloc() to initialize the
> > sites and allows us to run much earlier.
> > 
> 
> I'm confused. What was the need to have key->next store site pointers
> in order to move it up earlier?

The critical part was to not need an allocation.