linux-kernel - Re: [RFC PATCH 5/X] ptrace: mv task_struct->ptrace ptrace_task->pt_flags, kill ptrace

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Date:	Tue, 26 May 2009 13:55:37 -0700 (PDT)
From:	Roland McGrath <roland@...hat.com>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Christoph Hellwig <hch@...radead.org>, Ingo Molnar <mingo@...e.hu>,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 5/X] ptrace: mv task_struct->ptrace
	ptrace_task->pt_flags, kill ptrace_link()

>  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
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