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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 57862C77B60 for ; Sun, 30 Apr 2023 19:01:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229784AbjD3TBX (ORCPT ); Sun, 30 Apr 2023 15:01:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42782 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229452AbjD3TBV (ORCPT ); Sun, 30 Apr 2023 15:01:21 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2503D1BD5 for ; Sun, 30 Apr 2023 12:00:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1682881233; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=JPGpc4sz+9Nz9cOOaOox7Yqqqw3srJbqMl4YmzfUBsY=; b=Wqxcw+KVYIdzq5uUD0pNkrikPw6bR82zwszNEE24HaBX7QjaVeooFJpaG/UZRywIwsmRL1 27U7KqboPe00cX7urCRY74Zl6MXKIRmQn4DEJmkDs1yqDqf5BnUzxgmoloikE7LGr4qr0s jsBCoJsSZFFgwjPhvbZOMXzNLlKgC7M= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-391-JK5xjE3dNOCfg9bNWMJJlQ-1; Sun, 30 Apr 2023 15:00:31 -0400 X-MC-Unique: JK5xjE3dNOCfg9bNWMJJlQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id AD4573C0E213; Sun, 30 Apr 2023 19:00:30 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.224.26]) by smtp.corp.redhat.com (Postfix) with SMTP id 0E54940C6EC4; Sun, 30 Apr 2023 19:00:28 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Sun, 30 Apr 2023 21:00:19 +0200 (CEST) Date: Sun, 30 Apr 2023 21:00:16 +0200 From: Oleg Nesterov To: David Laight Cc: 'Josh Poimboeuf' , Peter Zijlstra , Thomas Gleixner , Vernon Lovejoy , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] x86/show_trace_log_lvl: ensure stack pointer is aligned, again Message-ID: <20230430190016.GB606@redhat.com> References: <20230427140054.GA17800@redhat.com> <20230428043158.r5omehiaqawcac2y@treble> <20230428065513.GA22111@redhat.com> <20230428235747.b5smutdttv5eeopi@treble> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.1 on 10.11.54.2 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/30, David Laight wrote: > > From: Josh Poimboeuf > > Sent: 29 April 2023 00:58 > > > > On Fri, Apr 28, 2023 at 08:55:13AM +0200, Oleg Nesterov wrote: > > > On 04/27, Josh Poimboeuf wrote: > > > > > > > > On Thu, Apr 27, 2023 at 04:00:54PM +0200, Oleg Nesterov wrote: > > > > > + stack = PTR_ALIGN(stack, sizeof(long)); > > > > > for ( ; stack; stack = PTR_ALIGN(stack_info.next_sp, sizeof(long))) { > > > > > const char *stack_name; > > > > > > > > Seems reasonable, though 'stack' is already initialized a few lines > > > > above this, so it would be cleaner to do the PTR_ALIGN then. Or even > > > > better, just move it all to the for loop: > > > > > > > > for (stack = PTR_ALIGN(stack ? : get_stack_pointer(task, regs)); > > > > stack; > > > > stack = PTR_ALIGN(stack_info.next_sp, sizeof(long))) { > > > > > > We decided to make the simplest one-liner fix, but I was thinking about > > > > > > for ( stack = stack ? : get_stack_pointer(task, regs); > > > (stack = PTR_ALIGN(stack, sizeof(long))); > > > stack = stack_info.next_sp) > > > { > > > ... > > > > > > to factout out the annoying PTR_ALIGN(). Will it work for you? > > > > I'd rather not, that's a little *too* clever, IMO. > > I'd leave the initialisation outside the loop and move > the PTR_ALIGN() into the loop so that the 'for' fits on one line: > if (!stack) > stack = get_stack_pointer(task, regs); > for (; stack; stack = stack_info.next_sp) { > const char ... > stack = PTR_ALIGN(stack, sizeof(long)); Well to me this looks better than V2 I've sent. Although to be honest I'd prefer the initial one-liner fix, but this doesn't mater. I am fine either way, I guess Vernon too. So I leave this to you and Josh, please tell us if we should send V3 or not. Oleg.