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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 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 09108C54FD0 for ; Fri, 24 Apr 2020 18:32:25 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id AFE7720781 for ; Fri, 24 Apr 2020 18:32:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AFE7720781 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4982pG5FMLzDqfL for ; Sat, 25 Apr 2020 04:32:22 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=198.145.29.99; helo=mail.kernel.org; envelope-from=srs0=19w6=6i=goodmis.org=rostedt@kernel.org; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=goodmis.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4982lb0vfCzDqRZ for ; Sat, 25 Apr 2020 04:30:02 +1000 (AEST) Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (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 3D46A20774; Fri, 24 Apr 2020 18:30:00 +0000 (UTC) Date: Fri, 24 Apr 2020 14:29:58 -0400 From: Steven Rostedt To: "Naveen N. Rao" Subject: Re: [PATCH 1/3] powerpc: Properly return error code from do_patch_instruction() Message-ID: <20200424142958.39d10d8f@gandalf.local.home> In-Reply-To: <1587751422.a0nwb9dqfv.naveen@linux.ibm.com> References: <16070946-1185-2aad-62fe-f4ed9cd4eefe@c-s.fr> <20200424091552.497dc719@gandalf.local.home> <1587751422.a0nwb9dqfv.naveen@linux.ibm.com> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Fri, 24 Apr 2020 23:37:06 +0530 "Naveen N. Rao" wrote: > >> Le 23/04/2020 =C3=A0 17:09, Naveen N. Rao a =C3=A9crit=C2=A0: =20 > >> > With STRICT_KERNEL_RWX, we are currently ignoring return value from > >> > __patch_instruction() in do_patch_instruction(), resulting in the er= ror > >> > not being propagated back. Fix the same. =20 > >>=20 > >> Good patch. > >>=20 > >> Be aware that there is ongoing work which tend to wanting to replace=20 > >> error reporting by BUG_ON() . See=20 > >> https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=3D16600= 3 =20 > >=20 > > Thanks for the reference. I still believe that WARN_ON() should be used= in > > 99% of the cases, including here. And only do a BUG_ON() when you know > > there's no recovering from it. =20 >=20 > I'm not sure if you meant that we should have a WARN_ON() in=20 > patch_instruction(), or if it was about the users of=20 > patch_instruction(). As you're well aware, ftrace likes to do its own=20 > WARN_ON() if any of its operations fail through ftrace_bug(). That was=20 > the reason I didn't add anything here. I'm fine with that too, and better reason not to call BUG_ON(), because I'm guessing if we crash, we never make it to the ftrace_bug() which reports information that can be used to debug what went wrong. -- Steve