Re: [PATCH 05/48] percpu: Add preemption checks to __this_cpu ops

From: Christoph Lameter
Date: Tue Mar 04 2014 - 22:27:25 EST


On Tue, 4 Mar 2014, Andrew Morton wrote:

> > print_symbol("caller is %s\n", (long)__builtin_return_address(0));
> > dump_stack();
>
> I wonder if there's any point in printing __builtin_return_address.
> Doesn't dump_stack() tell us the same thing?

Yes it does. However, it was there before and software may scan the logs
for it.

> > +notrace void __this_cpu_preempt_check(const char *op)
> > +{
> > + char text[40];
> > +
> > + snprintf(text, sizeof(text), "__this_cpu_%s()", op);
> > + check_preemption_disabled(text);
> > +}
>
> I'd like to see a comment here telling scared readers why this can
> never overflow text[].

Ok. I can also add VM_BUG_ON(strlen(op) >= sizeof(text)) ?

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