linux-kernel - Re: [PATCH 1/3] futex_find_get_task: remove an obscure EXIT

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Date:	Tue, 22 Aug 2006 22:34:31 +0400
From:	Oleg Nesterov <oleg@...sign.ru>
To:	Bill Huey <billh@...ppy.monkey.org>
Cc:	Andrew Morton <akpm@...l.org>, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Steven Rostedt <rostedt@...dmis.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] futex_find_get_task: remove an obscure EXIT_ZOMBIE check

On 08/21, Bill Huey wrote:
>
> On Mon, Aug 21, 2006 at 09:06:04PM +0400, Oleg Nesterov wrote:
> > (Compile tested).
> > 
> > futex_find_get_task:
> > 
> > 	if (p->state == EXIT_ZOMBIE || p->exit_state == EXIT_ZOMBIE)
> > 		return NULL;
> > 
> > I can't understand this. First, p->state can't be EXIT_ZOMBIE. The ->exit_state
> > check looks strange too. Sub-threads or tasks whose ->parent ignores SIGCHLD go
> > directly to EXIT_DEAD state (I am ignoring a ptrace case). Why EXIT_DEAD tasks
> > should be ok? Yes, EXIT_ZOMBIE is more important (a task may stay zombie for a
> > long time), but this doesn't mean we should explicitely ignore other EXIT_XXX
> > states.
> 
> The p->state variable for EXIT_ZOMBIE is only live for some mystery architecture
> in arch/xtensa/kernel/ptrace.c

Thanks. This

	case PTRACE_KILL:
		ret = 0;
		if (child->state == EXIT_ZOMBIE)	/* already dead */
			break;

is an obvious bug, I beleive. May I suggest you to make a patch?

Oleg.

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