Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751986AbbHEKPU (ORCPT ); Wed, 5 Aug 2015 06:15:20 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:56931 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750881AbbHEKPS (ORCPT ); Wed, 5 Aug 2015 06:15:18 -0400 Date: Wed, 5 Aug 2015 12:15:06 +0200 From: Peter Zijlstra To: Kaixu Xia Cc: ast@plumgrid.com, davem@davemloft.net, acme@kernel.org, mingo@redhat.com, masami.hiramatsu.pt@hitachi.com, jolsa@kernel.org, daniel@iogearbox.net, wangnan0@huawei.com, linux-kernel@vger.kernel.org, pi3orama@163.com, hekuang@huawei.com, netdev@vger.kernel.org Subject: Re: [PATCH v6 3/4] bpf: Implement function bpf_perf_event_read() that get the selected hardware PMU conuter Message-ID: <20150805101506.GY18673@twins.programming.kicks-ass.net> References: <1438678696-88289-1-git-send-email-xiakaixu@huawei.com> <1438678696-88289-4-git-send-email-xiakaixu@huawei.com> <20150805100425.GZ25159@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150805100425.GZ25159@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 573 Lines: 15 On Wed, Aug 05, 2015 at 12:04:25PM +0200, Peter Zijlstra wrote: > On Tue, Aug 04, 2015 at 08:58:15AM +0000, Kaixu Xia wrote: > > + event->ctx->task != current) Strictly speaking we should hold rcu_read_lock around dereferencing event->ctx (or have IRQs disabled -- although I know Paul doesn't like us relying on that). -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/