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Date:   Thu, 17 Jun 2010 10:13:18 -0700
From:   David Daney <ddaney@caviumnetworks.com>
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To:     Jesper Nilsson <jesper@jni.nu>
CC:     Ralf Baechle <ralf@linux-mips.org>, linux-mips@linux-mips.org,
        linux-kernel@vger.kernel.org
Subject: Re: MIPS: return after handling coprocessor 2 exception
References: <20100617132554.GB24162@jni.nu>
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On 06/17/2010 06:25 AM, Jesper Nilsson wrote:
> Breaking here dropped us to the default code which always sends
> a SIGILL to the current process, no matter what the CU2 notifier says.
>
> Signed-off-by: Jesper Nilsson<jesper@jni.nu>
> ---
>   traps.c |    2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
> index 8bdd6a6..8527808 100644
> --- a/arch/mips/kernel/traps.c
> +++ b/arch/mips/kernel/traps.c
> @@ -976,7 +976,7 @@ asmlinkage void do_cpu(struct pt_regs *regs)
>
>   	case 2:
>   		raw_notifier_call_chain(&cu2_chain, CU2_EXCEPTION, regs);
> -		break;
> +		return;
>

What happens when the call chain is empty, and the proper action *is* 
SIGILL?

David Daney