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From: Roland McGrath <roland@redhat.com>
To: Oleg Nesterov <oleg@redhat.com>
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Cc: Christoph Hellwig <hch@infradead.org>, Ingo Molnar <mingo@elte.hu>,
       linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 5/X] ptrace: mv task_struct->ptrace
	ptrace_task->pt_flags, kill ptrace_link()
In-Reply-To: Oleg Nesterov's message of  Monday, 25 May 2009 02:00:08 +0200 <20090525000008.GA2228@redhat.com>
References: <20090525000008.GA2228@redhat.com>
X-Antipastobozoticataclysm: When George Bush projectile vomits antipasto on the Japanese.
Message-Id: <20090526205537.C5101FC2BD@magilla.sf.frob.com>
Date: Tue, 26 May 2009 13:55:37 -0700 (PDT)
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>  static inline int task_ptrace(struct task_struct *task)
>  {
> -	return task->ptrace;
> +	return unlikely(task->ptrace_task) ?
> +		task->ptrace_task->pt_flags : 0;

This merits a short comment reminding the reader that once ->ptrace_task is
allocated, it is never freed until @task is freed, so this access is always
safe.


Thanks,
Roland