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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, 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 BE253C33CAA for ; Tue, 21 Jan 2020 14:59:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9F40922314 for ; Tue, 21 Jan 2020 14:59:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729208AbgAUO7l convert rfc822-to-8bit (ORCPT ); Tue, 21 Jan 2020 09:59:41 -0500 Received: from eu-smtp-delivery-151.mimecast.com ([146.101.78.151]:53782 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726968AbgAUO7k (ORCPT ); Tue, 21 Jan 2020 09:59:40 -0500 Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-219-L5SrfWfSPdmKcjEtPs885Q-1; Tue, 21 Jan 2020 14:59:36 +0000 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) by AcuMS.aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Tue, 21 Jan 2020 14:59:35 +0000 Received: from AcuMS.Aculab.com ([fe80::43c:695e:880f:8750]) by AcuMS.aculab.com ([fe80::43c:695e:880f:8750%12]) with mapi id 15.00.1347.000; Tue, 21 Jan 2020 14:59:35 +0000 From: David Laight To: 'Peter Zijlstra' , Steven Rostedt CC: "linux-kernel@vger.kernel.org" , Ingo Molnar , Andrew Morton , Jiri Olsa , "Naveen N . Rao" , "Anil S Keshavamurthy" , "David S . Miller" , Namhyung Kim , =?iso-8859-1?Q?Toke_H=F8iland-J=F8rgensen?= , "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 Thread-Topic: [for-linus][PATCH 2/5] tracing/uprobe: Fix double perf_event linking on multiprobe uprobe Thread-Index: AQHV0GolckT49KM4+0+Ui2RvGIz8QKf1NT6Q Date: Tue, 21 Jan 2020 14:59:35 +0000 Message-ID: References: <20200121143847.609307852@goodmis.org> <20200121143956.600928887@goodmis.org> <20200121145009.GR14879@hirez.programming.kicks-ass.net> In-Reply-To: <20200121145009.GR14879@hirez.programming.kicks-ass.net> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-MC-Unique: L5SrfWfSPdmKcjEtPs885Q-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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: struct trace_probe_event { struct { struct trace_event_call call; struct list_head files; struct list_head probes; }; char data[0]; }; David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)