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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable 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 8C26FC43381 for ; Mon, 4 Mar 2019 12:29:43 +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 13D8A2070B for ; Mon, 4 Mar 2019 12:29:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 13D8A2070B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com 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 44CfVF0ycMzDqDh for ; Mon, 4 Mar 2019 23:29:41 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=arm.com (client-ip=217.140.101.70; helo=foss.arm.com; envelope-from=sudeep.holla@arm.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=arm.com Received: from foss.arm.com (usa-sjc-mx-foss1.foss.arm.com [217.140.101.70]) by lists.ozlabs.org (Postfix) with ESMTP id 44CfRc2wRXzDqGY for ; Mon, 4 Mar 2019 23:27:22 +1100 (AEDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 436BDA78; Mon, 4 Mar 2019 04:27:19 -0800 (PST) Received: from e107155-lin (e107155-lin.cambridge.arm.com [10.1.196.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 960DB3F575; Mon, 4 Mar 2019 04:27:16 -0800 (PST) Date: Mon, 4 Mar 2019 12:27:11 +0000 From: Sudeep Holla To: Segher Boessenkool Subject: Re: [PATCH 2/6] ptrace: introduce ptrace_syscall_enter to consolidate PTRACE_SYSEMU handling Message-ID: <20190304122711.GA28624@e107155-lin> References: <20190228183220.15626-1-sudeep.holla@arm.com> <20190228183220.15626-3-sudeep.holla@arm.com> <20190304104643.GA28643@e107155-lin> <20190304122331.GG3969@gate.crashing.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190304122331.GG3969@gate.crashing.org> User-Agent: Mutt/1.9.4 (2018-02-28) 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: "Haibo Xu \(Arm Technology China\)" , Steve Capper , Catalin Marinas , "jdike@addtoit.com" , "x86@kernel.org" , Will Deacon , "linux-kernel@vger.kernel.org" , Oleg Nesterov , Ingo Molnar , Paul Mackerras , Richard Weinberger , Thomas Gleixner , "Bin Lu \(Arm Technology China\)" , "linuxppc-dev@lists.ozlabs.org" , "linux-arm-kernel@lists.infradead.org" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Mon, Mar 04, 2019 at 06:23:32AM -0600, Segher Boessenkool wrote: > On Mon, Mar 04, 2019 at 10:46:43AM +0000, Sudeep Holla wrote: > > On Mon, Mar 04, 2019 at 08:03:47AM +0000, Haibo Xu (Arm Technology China) wrote: > > > On 2019/3/1 2:32, Sudeep Holla wrote: > > > > +long ptrace_syscall_enter(struct pt_regs *regs) > > > > +{ > > > > +#ifdef TIF_SYSCALL_EMU > > > > + if (test_thread_flag(TIF_SYSCALL_EMU)) { > > > > + if (tracehook_report_syscall_entry(regs)); > > > > > > Shall we remove the semi-colon at end of the above line? > > > > Added intentionally to keep GCC happy. > > GCC warns because the user explicitly asked for it, with __must_check. > If you want to do things with an "if" like this, you should write e.g. > > if (tracehook_report_syscall_entry(regs)) > /* > * We can ignore the return code here, because of > * X and Y and Z. > */ > ; > > Or it probably is nicer to use a block: > > if (tracehook_report_syscall_entry(regs)) { > /* > * We can ignore the return code here, because of > * X and Y and Z. > */ > } > > The point is, you *always* should have a nice fat comment if you are > ignoring the return code of a __must_check function. > Agreed, will add the comment. -- Regards, Sudeep