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SubjectRe: [PATCH v6 4/7] arm64: Add ftrace support
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On Thu, 2014-03-13 at 17:08 +0000, Will Deacon wrote:

> > + /*
> > + * Note:
> > + * No protection against faulting at *parent, which may be seen
> > + * on other archs. It's unlikely on AArch64.
> > + */
> > + old = *parent;
> > + *parent = return_hooker;
>
> return_hook? People might take it personally otherwise ;)

No, return_hooker is consistent with all the other archs. Hey, it's a
rugby position! Note, which I was when I played. ;-)

>
> > + trace.func = self_addr;
>
> in kernel/ftrace/ftrace.c there's an smb_wmb() between setting up
> tracing_graph_pause and setting the ret_stack with a comment saying:
>
> /* Make sure the tasks see the -1 first: */
>
> Why don't we have a corresponding read-barrier here?

The corresponding rmb is in kernel/trace/trace_function_graph
ftrace_push_return_trace().

-- Steve




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