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 S1757267AbbJVPiI (ORCPT <rfc822;w@1wt.eu>);
	Thu, 22 Oct 2015 11:38:08 -0400
Received: from mail-pa0-f49.google.com ([209.85.220.49]:34369 "EHLO
	mail-pa0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1757061AbbJVPiD (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Thu, 22 Oct 2015 11:38:03 -0400
Subject: Re: [PATCH net-next 2/3] bpf: introduce bpf_perf_event_output()
 helper
To: Peter Zijlstra <peterz@infradead.org>
References: <1445396556-4854-1-git-send-email-ast@kernel.org>
 <1445396556-4854-3-git-send-email-ast@kernel.org>
 <20151022135930.GN3604@twins.programming.kicks-ass.net>
Cc: "David S. Miller" <davem@davemloft.net>, Ingo Molnar <mingo@kernel.org>,
        Wang Nan <wangnan0@huawei.com>, He Kuang <hekuang@huawei.com>,
        Arnaldo Carvalho de Melo <acme@infradead.org>,
        Daniel Borkmann <daniel@iogearbox.net>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
From: Alexei Starovoitov <ast@plumgrid.com>
Message-ID: <562902DA.7010908@plumgrid.com>
Date: Thu, 22 Oct 2015 08:38:02 -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: <20151022135930.GN3604@twins.programming.kicks-ass.net>
Content-Type: text/plain; charset=windows-1252; 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 6:59 AM, Peter Zijlstra wrote:
>> +	if (unlikely(event->oncpu != smp_processor_id()))
>> >+		return -EOPNOTSUPP;
>> >+
>> >+	perf_sample_data_init(&sample_data, 0, 0);
>> >+	sample_data.raw = &raw;
>> >+	perf_event_output(event, &sample_data, regs);
>> >+	return 0;
>> >+}
> Note that this function also very much requires event to be local.

correct. that's why there is a dynamic check above to prevent buggy
programs causing issues.