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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 C75F4C432C0 for ; Thu, 21 Nov 2019 16:53:44 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 95145206CB for ; Thu, 21 Nov 2019 16:53:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="QL4FFjmZ"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="uiahZSH1" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 95145206CB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=qqL3q3QPuf2IapNq6GbZlNrtEX81XEGH9iUINXAk1uA=; b=QL4FFjmZUzr9Ng uS9Du/TFTy0qFerK5qcVeT/toYRTxYfSgqvmIT8xauZ8s7NUwT+EeRNjgIk04dVUgpji2VjjHWfzH bg5dFF2KuaoTJwpwPGcy6ky00nlSzxw0VTYDZQI+uwiaEu1zTMz+HzCdfBX30/Qhdqs2OpY+G3PLo YOYCm3U9TU3BxH6VjZsjR5CrUcFvbCaS+0Dy0aTdTSPvBFLFmQLTUJti0e5TtxQ3GNwLgOuK/1tbB DftC4+lqpN7OKyrf5ekwr4vBkt5Ct56ktLWCgVOa5fFdcQQpt/Xz3x/8pmQTbjRkul69UhpcO5Xo8 fRZqB5uOAnNjxj5KfjHA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iXpiB-0007zh-RU; Thu, 21 Nov 2019 16:53:43 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1iXpi8-0007yf-Q7 for linux-arm-kernel@lists.infradead.org; Thu, 21 Nov 2019 16:53:42 +0000 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 695D020658; Thu, 21 Nov 2019 16:53:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574355220; bh=tiskj4Iiwo7XYj1HnnEFdsnbTEE7Qj1OSyBblDXYNfw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=uiahZSH1KQvGQb3DvX1nOft6/wv/LG9SKgsWRLCztddQDHBNFmUOSrhgWZ2MVmqJ4 4V9ZwLUQVCxRsNkL5zAVejSbzlgqPwl9huYwFteE6EhHaAZLRCPLFm7xY6U6YnfWuh H6VjqkPO2QiQI8Od5TRKFtGNx5DqeoQUDJB+jU34= Date: Thu, 21 Nov 2019 16:53:35 +0000 From: Will Deacon To: Herbert Xu Subject: Re: [PATCH v2] buffer: Fix I/O error due to ARM read-after-read hazard Message-ID: <20191121165334.GB4905@willie-the-truck> References: <20191113104945.GC25900@willie-the-truck> <20191114132848.55atqtjshjmi2udl@gondor.apana.org.au> <20191120191839.GF4799@willie-the-truck> <20191121012533.3h6akm4oczswj7zr@gondor.apana.org.au> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20191121012533.3h6akm4oczswj7zr@gondor.apana.org.au> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191121_085340_865294_B18497F4 X-CRM114-Status: GOOD ( 12.06 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: axboe@kernel.dk, Richard.Earnshaw@arm.com, rabinv@axis.com, catalin.marinas@arm.com, vincent.whitchurch@axis.com, linux@armlinux.org.uk, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Nov 21, 2019 at 09:25:33AM +0800, Herbert Xu wrote: > On Wed, Nov 20, 2019 at 07:18:40PM +0000, Will Deacon wrote: > > > > > The Alpha barrier matters for pointers, how could it make a > > > difference for individual bits? > > > > I guess you could use the result of test_bit to index into an array or > > something? > > Can Alpha Assembly even do this without using a branch? Don't see why not: you can add the base address to the scaled result of test_bit and use that as the address register into a load instruction. Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel