linux-kernel - Re: [PATCH 22/24] i386: add TRACE_IRQS

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Date:	Mon, 12 Jan 2009 18:21:51 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	heukelum@...tmail.fm
Cc:	linux-kernel@...r.kernel.org, mingo@...e.hu, ak@...e.de,
	Dhaval Giani <dhaval@...ux.vnet.ibm.com>
Subject: Re: [PATCH 22/24] i386: add TRACE_IRQS_OFF for the nmi

On Tue, 2008-09-09 at 21:56 +0200, heukelum@...tmail.fm wrote:
> From: Alexander van Heukelum <heukelum@...tmail.fm>
> 
> At this point interrupts are off, so let's inform the tracing
> code of that fact before calling into C.

Sorry but this is an obvious dud, lockdep (and thus the irq state
tracer) aren't nmi safe.

Ingo, please revert, as people are already seeing lockdep warnings due
to this.

> Signed-off-by: Alexander van Heukelum <heukelum@...tmail.fm>
> ---
>  arch/x86/kernel/entry_32.S |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
> index a278505..2abdc9a 100644
> --- a/arch/x86/kernel/entry_32.S
> +++ b/arch/x86/kernel/entry_32.S
> @@ -849,6 +849,7 @@ nmi_stack_correct:
>  	pushl %eax
>  	CFI_ADJUST_CFA_OFFSET 4
>  	SAVE_ALL
> +	TRACE_IRQS_OFF
>  	xorl %edx,%edx		# zero error code
>  	movl %esp,%eax		# pt_regs pointer
>  	call do_nmi
> @@ -889,6 +890,7 @@ nmi_espfix_stack:
>  	pushl %eax
>  	CFI_ADJUST_CFA_OFFSET 4
>  	SAVE_ALL
> +	TRACE_IRQS_OFF
>  	FIXUP_ESPFIX_STACK		# %eax == %esp
>  	xorl %edx,%edx			# zero error code
>  	call do_nmi

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