linux-kernel - Re: [PATCH 5/5] ftrace, x86: do not depend on system state for kernel text info

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Date:	Fri, 20 Feb 2009 18:34:54 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Steven Rostedt <srostedt@...hat.com>
Subject: Re: [PATCH 5/5] ftrace, x86: do not depend on system state for
	kernel text info


* Steven Rostedt <rostedt@...dmis.org> wrote:

> From: Steven Rostedt <srostedt@...hat.com>
> 
> Andrew Morton pointed out that using SYSTEM_STATE is a bad idea
> since there is no guarantee to what its state will actually be.
> 
> Instead, I moved the check into the set_kernel_text_* functions
> themselves, and use a local variable to determine when it is
> OK to change the kernel text RW permissions.
> 
> Reported-by: Andrew Morton <akpm@...ux-foundation.org>
> Signed-off-by: Steven Rostedt <srostedt@...hat.com>
> ---
>  arch/x86/kernel/ftrace.c |    8 --------
>  arch/x86/mm/init_32.c    |   10 ++++++++++
>  arch/x86/mm/init_64.c    |   10 ++++++++++
>  3 files changed, 20 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
> index c9ba2f9..025d783 100644
> --- a/arch/x86/kernel/ftrace.c
> +++ b/arch/x86/kernel/ftrace.c
> @@ -28,20 +28,12 @@
>  
>  int ftrace_arch_modify_prepare(void)
>  {
> -	/* at boot up, we are still writable */
> -	if (system_state != SYSTEM_RUNNING)
> -		return 0;
> -

Since i suspect you'll rebase anyway, i'd suggest to squash this 
patch into patch #2, with credit to Andrew added.

	Ingo
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