From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 052ECC32771 for ; Wed, 22 Jan 2020 22:12:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C2E4E24673 for ; Wed, 22 Jan 2020 22:12:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579731161; bh=yXJTAtyUgF/n5VfVCpD4qaPRZD7eOBIuzPZVhbUeTL8=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=2SsY4lG2e+VPbekKTfz8zZr9IRR/OG1+2uDVaBm1ZkWtnZPu0sjYN6eC4uAIINwGJ 0bhJdLD5i/6QAFt/wMowUnUGE9WRMJaeWOFe1mGdSu9BgffNquaAex0WttaEOeNZq3 f+EqcbD7vQVnnIIZsxgUepOmp/vujlkzW/cEv/Lo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726219AbgAVWMk (ORCPT ); Wed, 22 Jan 2020 17:12:40 -0500 Received: from mail.kernel.org ([198.145.29.99]:53596 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725970AbgAVWMj (ORCPT ); Wed, 22 Jan 2020 17:12:39 -0500 Received: from devnote2 (NE2965lan1.rev.em-net.ne.jp [210.141.244.193]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7CE9021835; Wed, 22 Jan 2020 22:12:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579731158; bh=yXJTAtyUgF/n5VfVCpD4qaPRZD7eOBIuzPZVhbUeTL8=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=pvOuqmaRIpjkXG3GkKuNKB7TseHYe4VltsI+SVF8gTpuFw/Y69mtx5NJn6O7WsiPy wdEO/h0fAEhvzmxmMiHjSMpiJhrMDmTvPLNWI3PysmL0zvC5Zxz+P2o2FKO9ZL5iiX tfVH+5LKRTmDymKuOVKue15KuKBUZI6D6mZJFnAs= Date: Thu, 23 Jan 2020 07:12:14 +0900 From: Masami Hiramatsu To: Peter Zijlstra Cc: David Laight , Steven Rostedt , "linux-kernel@vger.kernel.org" , Ingo Molnar , Andrew Morton , Jiri Olsa , "Naveen N . Rao" , Anil S Keshavamurthy , "David S . Miller" , Namhyung Kim , Toke =?UTF-8?B?SMO4aWxhbmQtSsO4cmdl?= =?ISO-2022-JP?B?bnNlbg==?= , Jean-Tsung Hsiao , Jesper Dangaard Brouer , "stable@vger.kernel.org" , Arnaldo Carvalho de Melo , Arnaldo Carvalho de Melo , Masami Hiramatsu Subject: Re: [for-linus][PATCH 2/5] tracing/uprobe: Fix double perf_event linking on multiprobe uprobe Message-Id: <20200123071214.fb1975d25177963765511435@kernel.org> In-Reply-To: <20200121150605.GT14879@hirez.programming.kicks-ass.net> References: <20200121143847.609307852@goodmis.org> <20200121143956.600928887@goodmis.org> <20200121145009.GR14879@hirez.programming.kicks-ass.net> <20200121150605.GT14879@hirez.programming.kicks-ass.net> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 21 Jan 2020 16:06:05 +0100 Peter Zijlstra wrote: > On Tue, Jan 21, 2020 at 02:59:35PM +0000, David Laight wrote: > > From: Peter Zijlstra > > > Sent: 21 January 2020 14:50 > > > On Tue, Jan 21, 2020 at 09:38:49AM -0500, Steven Rostedt wrote: > > > > diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h > > > > index 4ee703728aec..03e4e180058d 100644 > > > > --- a/kernel/trace/trace_probe.h > > > > +++ b/kernel/trace/trace_probe.h > > > > @@ -230,6 +230,7 @@ struct trace_probe_event { > > > > struct trace_event_call call; > > > > struct list_head files; > > > > struct list_head probes; > > > > + char data[0]; > > > > }; > > > > > > Note that this relies on pure 'luck'. If you stick anything <4 bytes in > > > between the list_head and the data member it'll come unstuck real fast. > > > > Can you fix it by adding an unnamed struct as in: > > The trivial fix is like I suggested in the other thread: > > struct trace_uprobe_filter filters[0]; > > The alternative that Masami-San suggested should also work. I've sent a fix ( https://lkml.org/lkml/2020/1/21/1214 ) as Peter suggested, change the field to struct trace_uprobe_filter filters[0]; and change the code around that. Thank you, -- Masami Hiramatsu