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Subject: Re: [PATCH] powerpc: Make hard_irq_disable() do the right thing vs.
 irq tracing
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: "tiejun.chen" <tiejun.chen@windriver.com>
Date: Tue, 07 May 2013 17:25:20 +1000
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Cc: Scott Wood <scottwood@freescale.com>,
 Mihai Caraman <mihai.caraman@freescale.com>, linuxppc-dev@lists.ozlabs.org,
 kvm-ppc@vger.kernel.org
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On Tue, 2013-05-07 at 15:15 +0800, tiejun.chen wrote:
> Could we simplify this as follows:
> 
> +#define hard_irq_disable()     do {                    \
> +       __hard_irq_disable();                           \
> +       if (get_paca()->soft_enabled) {                 \
> +               trace_hardirqs_off();                   \
> +               get_paca()->soft_enabled = 0;           \
> +       }                                               \
> +       get_paca()->irq_happened |= PACA_IRQ_HARD_DIS;  \
> +} while(0)

I'd rather not. When lockdep is not enabled trace_hardirqs_off() is a
nop and thus we have no conditional at all which is arguably better...

Cheers,
Ben.