linux-kernel - Re: [RFC][PATCH 2/7][v4] Protect init from unwanted signals more

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Message-ID: <20081224163503.GF11593@redhat.com>
Date:	Wed, 24 Dec 2008 17:35:03 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>
Cc:	ebiederm@...ssion.com, roland@...hat.com, bastian@...di.eu.org,
	daniel@...ac.com, xemul@...nvz.org, containers@...ts.osdl.org,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCH 2/7][v4] Protect init from unwanted signals more

On 12/24, Sukadev Bhattiprolu wrote:
>
> -static int sig_ignored(struct task_struct *t, int sig)
> +static int sig_task_ignored(struct task_struct *t, int sig)
>  {
>  	void __user *handler;
>
> +	handler = sig_handler(t, sig);
> +
> +	if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
> +			(handler == SIG_IGN || handler == SIG_DFL))
> +		return 1;
> +	
> +	return sig_handler_ignored(handler, sig);

Well, really minor nit, but can't resist ;)

if we check both SIG_IGN and SIG_DFL, then why do we call
sig_handler_ignored() ? We can do

	if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE))
		return handler == SIG_IGN || handler == SIG_DFL;
	return sig_handler_ignored(handler, sig);

Or, we can do

	if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
			 handler == SIG_DFL)
		return 1;
	return sig_handler_ignored(handler, sig);

because sig_handler_ignored() checks SIG_IGN too.

Of course, this is a matter of taste only...

Oleg.

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