From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Fri, 13 Apr 2018 00:39:00 +0200 (CEST) Received: from smtp.codeaurora.org ([198.145.29.96]:46604 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S23990412AbeDLWisq9zi8 (ORCPT ); Fri, 13 Apr 2018 00:38:48 +0200 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 3E45C607EF; Thu, 12 Apr 2018 22:38:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1523572722; bh=I318nWpUI17AdKyMOjpJrAwJ3nFcOW7z/O/wD4KzMuI=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=C/g7/WIMWG3k0rAe7SfhEXGjuN0Ra25MDQNetLmVy93OjukmRoE5aX0vyekrHE/Zh rbA4aGmMnBWG+hhFC9MOHlBMZ44JXJLwfHmjBKAydY6XkRduHm4u+NzFZW5jCtKyz4 frqztzpqMo1ICxJ/Mjvfhq4c08c/1id+U+gkcWio= Received: from [10.235.228.150] (global_nat1_iad_fw.qualcomm.com [129.46.232.65]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: okaya@smtp.codeaurora.org) by smtp.codeaurora.org (Postfix) with ESMTPSA id A795B60264; Thu, 12 Apr 2018 22:38:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1523572721; bh=I318nWpUI17AdKyMOjpJrAwJ3nFcOW7z/O/wD4KzMuI=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=nykPcnD4MHgDHMV3CHrjxWgl1lOTSV2dZeZdwhCkKhq9qsHNDomuLCmRpqpPEBAl/ fsRnBeXqj1+NDImuaqJSS11ZXWFKoV1YKaLS5dyIBxRt63onwho8VDit5nxSwd3hzB 2YLL0krClf8Es6qMooCeZzavlbMBZyhj2dUndX74= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org A795B60264 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=okaya@codeaurora.org Subject: Re: [PATCH v3 2/2] MIPS: io: add a barrier after register read in readX() To: James Hogan Cc: linux-mips@linux-mips.org, arnd@arndb.de, timur@codeaurora.org, sulrich@codeaurora.org, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Ralf Baechle , Paul Burton , linux-kernel@vger.kernel.org References: <1522760109-16497-1-git-send-email-okaya@codeaurora.org> <1522760109-16497-2-git-send-email-okaya@codeaurora.org> <20180412215149.GA27802@saruman> <20180412215855.GB27802@saruman> From: Sinan Kaya Message-ID: <33c9c074-e0a5-7552-9993-269cd85101aa@codeaurora.org> Date: Thu, 12 Apr 2018 18:38:39 -0400 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <20180412215855.GB27802@saruman> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 63515 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: okaya@codeaurora.org Precedence: bulk List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: linux-mips X-List-ID: linux-mips List-subscribe: List-owner: List-post: List-archive: X-list: linux-mips On 4/12/2018 5:58 PM, James Hogan wrote: > On Thu, Apr 12, 2018 at 10:51:49PM +0100, James Hogan wrote: >> On Tue, Apr 03, 2018 at 08:55:04AM -0400, Sinan Kaya wrote: >>> While a barrier is present in writeX() function before the register write, >>> a similar barrier is missing in the readX() function after the register >>> read. This could allow memory accesses following readX() to observe >>> stale data. >>> >>> Signed-off-by: Sinan Kaya >>> Reported-by: Arnd Bergmann >> >> Both patches look like obvious improvements to me, so I'm happy to apply >> to my fixes branch. > > Though having said that, a comment to go with the rmb() (as suggested by > checkpatch) to detail the situation we're concerned about would be nice > to have. I can send a new version. No worries. Functional correctness is more important at this moment. I can accommodate any nice to haves. > > Cheers > James > -- Sinan Kaya Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.