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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 2700FC433E0 for ; Tue, 26 May 2020 19:46:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 035FD208B8 for ; Tue, 26 May 2020 19:46:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590522415; bh=RaZmosue4ssXAe/hL4EcL9bo7edRNvGkgXFzuwwE8Vs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=qNdvgdMqVA040Wp2RrcAzggDBQJcJ/OndcfTCc0lM9jhWzgJFGOj+B7iIyg+t3MhJ eDPF3zGqaBDsL8AGfeVpUdGxGxjAvwdHKLfNyvqfrGAboQ43sZr1mJ7mG45Q0sW9aY 9R6wKHWJBA0vfWYNRgds37SiWjEXy6GYRhfmg360= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390126AbgEZTqy (ORCPT ); Tue, 26 May 2020 15:46:54 -0400 Received: from mail.kernel.org ([198.145.29.99]:38422 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389277AbgEZTqx (ORCPT ); Tue, 26 May 2020 15:46:53 -0400 Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (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 272E12086A; Tue, 26 May 2020 19:46:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590522413; bh=RaZmosue4ssXAe/hL4EcL9bo7edRNvGkgXFzuwwE8Vs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=koDImTcZ4jx1g4tTY5/IvaZ0wpBkbrCaKpv2YtCnvjMnwpHa04/0PNBu0tGV8Yzzj 8w7IgjVSHhiaeSLy+jDwtVycS9LmC/eWlDrNnhgIjwIBNPqGfjILccONNfJAPUbuAq df+SiPYuJrVHvJ1lN2f5ffzGlwpJpssiepy3kvcI= Date: Tue, 26 May 2020 20:46:48 +0100 From: Will Deacon To: Catalin Marinas Cc: Anshuman Khandual , linux-arm-kernel@lists.infradead.org, mark.rutland@arm.com, Suzuki K Poulose , Mark Brown , linux-kernel@vger.kernel.org Subject: Re: [PATCH V2] arm64/cpufeature: Add get_arm64_ftr_reg_nowarn() Message-ID: <20200526194648.GA2206@willie-the-truck> References: <1590500353-28082-1-git-send-email-anshuman.khandual@arm.com> <20200526150135.GI17051@gaia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200526150135.GI17051@gaia> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 26, 2020 at 04:01:35PM +0100, Catalin Marinas wrote: > On Tue, May 26, 2020 at 07:09:13PM +0530, Anshuman Khandual wrote: > > @@ -632,8 +654,6 @@ static void __init init_cpu_ftr_reg(u32 sys_reg, u64 new) > > const struct arm64_ftr_bits *ftrp; > > struct arm64_ftr_reg *reg = get_arm64_ftr_reg(sys_reg); > > > > - BUG_ON(!reg); > > - > > for (ftrp = reg->ftr_bits; ftrp->width; ftrp++) { > > u64 ftr_mask = arm64_ftr_mask(ftrp); > > s64 ftr_new = arm64_ftr_value(ftrp, new); > > @@ -762,7 +782,6 @@ static int check_update_ftr_reg(u32 sys_id, int cpu, u64 val, u64 boot) > > { > > struct arm64_ftr_reg *regp = get_arm64_ftr_reg(sys_id); > > > > - BUG_ON(!regp); > > update_cpu_ftr_reg(regp, val); > > if ((boot & regp->strict_mask) == (val & regp->strict_mask)) > > return 0; > > @@ -776,9 +795,6 @@ static void relax_cpu_ftr_reg(u32 sys_id, int field) > > const struct arm64_ftr_bits *ftrp; > > struct arm64_ftr_reg *regp = get_arm64_ftr_reg(sys_id); > > > > - if (WARN_ON(!regp)) > > - return; > > I think Will wanted an early return in all these functions not just > removing the BUG_ON(). I'll let him clarify. Yes, the callers need to check the pointer and return early. Will