Re: [PATCH] ftrace/x86: fix x86-32 triple fault with graph tracing and suspend-to-ram

From: Steven Rostedt
Date: Mon Mar 27 2017 - 11:24:50 EST


On Mon, 27 Mar 2017 17:01:53 +0200
Paul Menzel <pmenzel@xxxxxxxxxxxxx> wrote:

> > + /*
> > + * When resuming from suspend-to-ram, this function can be indirectly
> > + * called from early CPU startup code while the CPU is in real mode,
> > + * which would fail miserably. Make sure the stack pointer is a
> > + * virtual address.
> > + *
> > + * This check isn't as accurate as virt_addr_valid(), but it should be
> > + * good enough for this purpose, and it's fast.
> > + */
> > + if (unlikely((long)__builtin_frame_address(0) >= 0)) return;
>
> The coding style requires the `return;` to be on a separate line.

Correct, and new versions of a patch should always start a new thread
(unless it's a single update of a patch in a long patch series).
Otherwise they get ignored. (hint hint)

-- Steve



>
> > +
> > if (unlikely(ftrace_graph_is_dead()))
> > return;
>