Date: Mon, 20 Dec 2010 15:59:56 +0100
From: Oleg Nesterov <oleg@redhat.com>
To: Tejun Heo <tj@kernel.org>
Cc: roland@redhat.com, linux-kernel@vger.kernel.org,
        torvalds@linux-foundation.org, akpm@linux-foundation.org, rjw@sisk.pl,
        jan.kratochvil@redhat.com
Subject: Re: [PATCH 04/16] ptrace: kill tracehook_notify_jctl()
Message-ID: <20101220145956.GC11583@redhat.com>
References: <1291654624-6230-1-git-send-email-tj@kernel.org> <1291654624-6230-5-git-send-email-tj@kernel.org>
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On 12/06, Tejun Heo wrote:
>
> tracehook_notify_jctl() aids in determining whether and what to report
> to the parent when a task is stopped or continued.  The function also
> adds an extra requirement that siglock may be released across it,
> which is currently unused and quite difficult to satisfy in
> well-defined manner.

OK. I agree, tracehook_notify_jctl() looks very unobvious, especially
because it is not really used currently.

The patch looks correct, except

> @@ -1853,21 +1850,19 @@ relock:
>  	if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
>  		int why;
>
> -		if (signal->flags & SIGNAL_CLD_CONTINUED)
> +		if (task_ptrace(current) ||
> +		    (signal->flags & SIGNAL_CLD_CONTINUED))
>  			why = CLD_CONTINUED;
>  		else
>  			why = CLD_STOPPED;

Hmm, I can't understand this.

task_ptrace() should not turn CLD_STOPPED in CLD_CONTINUED?

Looking ahead, it _seems_ that the next patches keep this logic,
could you explain?

Oleg.

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