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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham 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 B0A52C04AB6 for ; Fri, 31 May 2019 12:25:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 82AEB268C2 for ; Fri, 31 May 2019 12:25:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727359AbfEaMZR (ORCPT ); Fri, 31 May 2019 08:25:17 -0400 Received: from mx2.suse.de ([195.135.220.15]:33508 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726330AbfEaMZR (ORCPT ); Fri, 31 May 2019 08:25:17 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 42AA4AD76; Fri, 31 May 2019 12:25:16 +0000 (UTC) Date: Fri, 31 May 2019 14:25:15 +0200 (CEST) From: Miroslav Benes To: Petr Mladek cc: Jiri Kosina , Josh Poimboeuf , Joe Lawrence , Kamalesh Babulal , live-patching@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/3] stacktrace: Remove superfluous WARN_ONCE() from save_stack_trace_tsk_reliable() In-Reply-To: <20190531074147.27616-2-pmladek@suse.com> Message-ID: References: <20190531074147.27616-1-pmladek@suse.com> <20190531074147.27616-2-pmladek@suse.com> User-Agent: Alpine 2.21 (LSU 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 31 May 2019, Petr Mladek wrote: > WARN_ONCE() in the generic save_stack_trace_tsk_reliable() is superfluous. > > The information is passed also via the return value. The only current > user klp_check_stack() writes its own warning when the reliable stack > traces are not supported. Other eventual users might want its own error > handling as well. > > Signed-off-by: Petr Mladek > Acked-by: Miroslav Benes > Reviewed-by: Kamalesh Babulal > --- > kernel/stacktrace.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/kernel/stacktrace.c b/kernel/stacktrace.c > index 5667f1da3ede..8d088408928d 100644 > --- a/kernel/stacktrace.c > +++ b/kernel/stacktrace.c > @@ -259,7 +259,6 @@ __weak int > save_stack_trace_tsk_reliable(struct task_struct *tsk, > struct stack_trace *trace) > { > - WARN_ONCE(1, KERN_INFO "save_stack_tsk_reliable() not implemented yet.\n"); > return -ENOSYS; > } Do we even need the weak function now after Thomas' changes to kernel/stacktrace.c? - livepatch is the only user and it calls stack_trace_save_tsk_reliable() - x86 defines CONFIG_ARCH_STACKWALK and CONFIG_HAVE_RELIABLE_STACKTRACE, so it has stack_trace_save_tsk_reliable() implemented and it calls arch_stack_walk_reliable() - powerpc defines CONFIG_HAVE_RELIABLE_STACKTRACE and does not have CONFIG_ARCH_STACKWALK. It also has stack_trace_save_tsk_reliable() implemented and it calls save_stack_trace_tsk_reliable(), which is implemented in arch/powerpc/ - all other archs do not have CONFIG_HAVE_RELIABLE_STACKTRACE and there is stack_trace_save_tsk_reliable() returning ENOSYS for these cases in include/linux/stacktrace.c Miroslav