linux-kernel - Re: [PATCH] powerpc: _exception: kill the obsolete code under is_global

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Message-ID: <1257901974.2140.11.camel@pasglop>
Date:	Wed, 11 Nov 2009 12:12:54 +1100
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Geert Uytterhoeven <Geert.Uytterhoeven@...ycom.com>,
	Kumar Gala <galak@...nel.crashing.org>,
	Liu Yu <yu.liu@...escale.com>,
	Roland McGrath <roland@...hat.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] powerpc: _exception: kill the obsolete code under
 is_global_init()

On Tue, 2009-11-10 at 01:25 +0100, Oleg Nesterov wrote:
> The code under "if (is_global_init())" is bogus, and is_global_init()
> itself is not right in mt case.
> 
> Contrary to what the comment says, nowadays force_sig_info() does kill
> init even if the handler is SIG_DFL. Note that force_sig_info() clears
> SIGNAL_UNKILLABLE exactly for this case.
> 
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>
> ---

Thanks. I'll take that one.

Cheers,
Ben.

>  arch/powerpc/kernel/traps.c |   22 ----------------------
>  1 file changed, 22 deletions(-)
> 
> --- TH/arch/powerpc/kernel/traps.c~PPC_EXCEPTION_DONT_CK_INIT	2009-11-10 01:03:23.000000000 +0100
> +++ TH/arch/powerpc/kernel/traps.c	2009-11-10 01:06:41.000000000 +0100
> @@ -198,28 +198,6 @@ void _exception(int signr, struct pt_reg
>  	info.si_code = code;
>  	info.si_addr = (void __user *) addr;
>  	force_sig_info(signr, &info, current);
> -
> -	/*
> -	 * Init gets no signals that it doesn't have a handler for.
> -	 * That's all very well, but if it has caused a synchronous
> -	 * exception and we ignore the resulting signal, it will just
> -	 * generate the same exception over and over again and we get
> -	 * nowhere.  Better to kill it and let the kernel panic.
> -	 */
> -	if (is_global_init(current)) {
> -		__sighandler_t handler;
> -
> -		spin_lock_irq(&current->sighand->siglock);
> -		handler = current->sighand->action[signr-1].sa.sa_handler;
> -		spin_unlock_irq(&current->sighand->siglock);
> -		if (handler == SIG_DFL) {
> -			/* init has generated a synchronous exception
> -			   and it doesn't have a handler for the signal */
> -			printk(KERN_CRIT "init has generated signal %d "
> -			       "but has no handler for it\n", signr);
> -			do_exit(signr);
> -		}
> -	}
>  }
>  
>  #ifdef CONFIG_PPC64


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