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 BEFA5EC875E for ; Thu, 7 Sep 2023 23:37:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233136AbjIGXhK (ORCPT ); Thu, 7 Sep 2023 19:37:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53130 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231792AbjIGXhJ (ORCPT ); Thu, 7 Sep 2023 19:37:09 -0400 Received: from out4-smtp.messagingengine.com (out4-smtp.messagingengine.com [66.111.4.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2881A1BD2 for ; Thu, 7 Sep 2023 16:37:06 -0700 (PDT) Received: from compute1.internal (compute1.nyi.internal [10.202.2.41]) by mailout.nyi.internal (Postfix) with ESMTP id 5E4CC5C01BA; Thu, 7 Sep 2023 19:37:05 -0400 (EDT) Received: from mailfrontend1 ([10.202.2.162]) by compute1.internal (MEProxy); Thu, 07 Sep 2023 19:37:05 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:content-type:date:date :feedback-id:feedback-id:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:sender:subject :subject:to:to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender :x-sasl-enc; s=fm1; t=1694129825; x=1694216225; bh=XTtOj1phX1oc3 nOxB5P9Xam0a+SUp0ixshRnNwtj29g=; b=HA95W2kXef4fcqozH7ZQyTE6NJNKH /MzXOmjB4ymc/2ONGMAawakp8KJe0vsRaHwUe4BtJjDe9sWbDIuaEKA2XAhS09pm 6yOTE1lxTApvGkNEzQJv7XHtaWdkgY2+zpPYV6iPbFVa6EJMzr2OUw6dE2OFVxGS kOEiw4xbSQ39bAdY5cJfTGnLWblw78z95tY0dDTSa9pJFV8Fzri3DOsiiTbyT1ma lZIqKT+DWDg4jbUrIt8tcnIb2rxdvE2ec0AfD2DobWhw6rGWSvXVs6Oz88Dl3OR8 H2vAawJGWop+8WfDZopdDk48OqDDjRVMOMHTeVL0t8qnMl5/60VUwYbNw== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedviedrudehiedgvdehucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhepfffhvfevufgjkfhfgggtsehttdertddttddvnecuhfhrohhmpefhihhnnhcu vfhhrghinhcuoehfthhhrghinheslhhinhhugidqmheikehkrdhorhhgqeenucggtffrrg htthgvrhhnpeelueehleehkefgueevtdevteejkefhffekfeffffdtgfejveekgeefvdeu heeuleenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpe hfthhhrghinheslhhinhhugidqmheikehkrdhorhhg X-ME-Proxy: Feedback-ID: i58a146ae:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Thu, 7 Sep 2023 19:37:02 -0400 (EDT) Date: Fri, 8 Sep 2023 09:37:12 +1000 (AEST) From: Finn Thain To: Geert Uytterhoeven cc: linux-m68k@lists.linux-m68k.org, Arnd Bergmann , Michael Schmitz , Philip Blundell , Greg Ungerer , Joshua Thompson , Sam Creasey , Laurent Vivier , linux-kernel@vger.kernel.org Subject: Re: [PATCH 25/52] m68k: apollo: Replace set but not used variable by READ_ONCE() In-Reply-To: <5406d0829d8204841c8cb8d265ca91a52cd22d2d.1694093327.git.geert@linux-m68k.org> Message-ID: <6e46156f-5a81-d245-63cd-8091605deee1@linux-m68k.org> References: <5406d0829d8204841c8cb8d265ca91a52cd22d2d.1694093327.git.geert@linux-m68k.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-m68k@vger.kernel.org On Thu, 7 Sep 2023, Geert Uytterhoeven wrote: > --- a/arch/m68k/apollo/config.c > +++ b/arch/m68k/apollo/config.c > @@ -146,13 +146,11 @@ void __init config_apollo(void) > > irqreturn_t dn_timer_int(int irq, void *dev_id) > { > - volatile unsigned char x; > - > legacy_timer_tick(1); > timer_heartbeat(); > > - x = *(volatile unsigned char *)(apollo_timer + 3); > - x = *(volatile unsigned char *)(apollo_timer + 5); > + READ_ONCE(*(volatile unsigned char *)(apollo_timer + 3)); > + READ_ONCE(*(volatile unsigned char *)(apollo_timer + 5)); > > return IRQ_HANDLED; > } > I believe the volatile cast is redundant here, as READ_ONCE does that. Perhaps the remaining cast could be deduplicated like so: - volatile unsigned char x; + unsigned char *at = (unsigned char *)apollo_timer; legacy_timer_tick(1); timer_heartbeat(); - x = *(volatile unsigned char *)(apollo_timer + 3); - x = *(volatile unsigned char *)(apollo_timer + 5); + READ_ONCE(*(at + 3)); + READ_ONCE(*(at + 5));