From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1752215AbbJWCbD (ORCPT <rfc822;w@1wt.eu>);
	Thu, 22 Oct 2015 22:31:03 -0400
Received: from mail-pa0-f45.google.com ([209.85.220.45]:35288 "EHLO
	mail-pa0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1751017AbbJWCbA (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Thu, 22 Oct 2015 22:31:00 -0400
Subject: Re: [PATCH v3 net-next] bpf: fix bpf_perf_event_read() helper
To: "Wangnan (F)" <wangnan0@huawei.com>,
        "David S. Miller" <davem@davemloft.net>
References: <1445559014-4667-1-git-send-email-ast@kernel.org>
 <56299992.8040002@huawei.com>
Cc: Ingo Molnar <mingo@kernel.org>, Peter Zijlstra <a.p.zijlstra@chello.nl>,
        He Kuang <hekuang@huawei.com>, Kaixu Xia <xiakaixu@huawei.com>,
        Daniel Borkmann <daniel@iogearbox.net>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
From: Alexei Starovoitov <ast@plumgrid.com>
Message-ID: <56299BE1.3000607@plumgrid.com>
Date: Thu, 22 Oct 2015 19:30:57 -0700
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:38.0)
 Gecko/20100101 Thunderbird/38.3.0
MIME-Version: 1.0
In-Reply-To: <56299992.8040002@huawei.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 10/22/15 7:21 PM, Wangnan (F) wrote:
>> +    if (attr->inherit)
>> +        goto err;
>> +
>
> Since Peter suggest it is pointless for a system-wide perf_event
> has inherit bit set [1], I think it should be safe to enable
> system-wide perf_event pass this check?

here we don't know whether it's system wide or not, so the check
is needed.
The patch is the fix that should have been there from day one.
We must be safe first and relax later.