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

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Message-ID: <20170327112433.728ba8c1@gandalf.local.home>
Date:   Mon, 27 Mar 2017 11:24:33 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Paul Menzel <pmenzel@...gen.mpg.de>
Cc:     Josh Poimboeuf <jpoimboe@...hat.com>,
        Ingo Molnar <mingo@...nel.org>, Len Brown <lenb@...nel.org>,
        linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
        x86@...nel.org, Borislav Petkov <bp@...en8.de>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>
Subject: Re: [PATCH] ftrace/x86: fix x86-32 triple fault with graph tracing
 and suspend-to-ram

On Mon, 27 Mar 2017 17:01:53 +0200
Paul Menzel <pmenzel@...gen.mpg.de> 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;  
>