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Date: Thu, 8 Sep 2011 20:42:15 +0200
From: Oleg Nesterov <oleg@redhat.com>
To: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Tejun Heo <tj@kernel.org>, linux-kernel@vger.kernel.org,
        Denys Vlasenko <vda.linux@googlemail.com>
Subject: Re: [PATCH v3] Simplify PTRACE_foo constants and PTRACE_SETOPTIONS
	code
Message-ID: <20110908184215.GA29439@redhat.com>
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On 09/08, Denys Vlasenko wrote:
>
>  static int ptrace_setoptions(struct task_struct *child, unsigned long data)
>  {
> ...
> +       if (data & ~(unsigned long)PTRACE_O_MASK) {
> +               child->ptrace &= ~PT_TRACE_MASK; /* historical bug */
> +               return -EINVAL;
> +       }

This is not right. You shouldn't simply return with -EINVAL, this change
adds another bug.  Note that the cuurrent code sets the new bits even if
it returns -EINVAL.

Oleg.