linux-kernel - Re: [PATCH v9 1/2] ARM: avoid tracers in soft

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Message-ID: <20140414105314.GB3530@arm.com>
Date:	Mon, 14 Apr 2014 11:53:14 +0100
From:	Will Deacon <will.deacon@....com>
To:	Sebastian Capella <sebastian.capella@...aro.org>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linaro-kernel@...ts.linaro.org" <linaro-kernel@...ts.linaro.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Russell King <linux@....linux.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Robin Holt <holt@....com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Konstantin Khlebnikov <k.khlebnikov@...sung.com>,
	Steven Capper <steve.capper@...aro.org>,
	Stephen Warren <swarren@...dia.com>, Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH v9 1/2] ARM: avoid tracers in soft_restart

Hi Sebastian,

On Tue, Mar 18, 2014 at 09:40:57PM +0000, Sebastian Capella wrote:
> Use of tracers in local_irq_disable is causes abort loops when called
> with irqs disabled using a temporary stack.  Replace local_irq_disable
> with raw_local_irq_disable instead to avoid tracers.

Do you have any more information about these aborts? At the time we call
local_irq_disable, the stack is still intact, so if the issue is simply
related to having any tracers active at the call_with_stack invocation, we'd
be better off disabling tracing here altogether.

Will

> Signed-off-by: Sebastian Capella <sebastian.capella@...aro.org>
> Cc: Russell King <linux@....linux.org.uk>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Will Deacon <will.deacon@....com>
> Cc: Robin Holt <holt@....com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Konstantin Khlebnikov <k.khlebnikov@...sung.com>
> Cc: Steven Capper <steve.capper@...aro.org>
> Cc: Stephen Warren <swarren@...dia.com>
> Cc: Tejun Heo <tj@...nel.org>
> ---
>  arch/arm/kernel/process.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
> index 92f7b15..f58b723 100644
> --- a/arch/arm/kernel/process.c
> +++ b/arch/arm/kernel/process.c
> @@ -100,7 +100,7 @@ void soft_restart(unsigned long addr)
>  	u64 *stack = soft_restart_stack + ARRAY_SIZE(soft_restart_stack);
>  
>  	/* Disable interrupts first */
> -	local_irq_disable();
> +	raw_local_irq_disable();
>  	local_fiq_disable();
>  
>  	/* Disable the L2 if we're the last man standing. */
> -- 
> 1.7.9.5
> 
> 
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