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_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 D7147C43441 for ; Wed, 21 Nov 2018 13:27:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9EAE8214DA for ; Wed, 21 Nov 2018 13:27:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="WM5jRn7l" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9EAE8214DA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.dk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-block-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729991AbeKVABv (ORCPT ); Wed, 21 Nov 2018 19:01:51 -0500 Received: from mail-pl1-f193.google.com ([209.85.214.193]:46890 "EHLO mail-pl1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729787AbeKVABv (ORCPT ); Wed, 21 Nov 2018 19:01:51 -0500 Received: by mail-pl1-f193.google.com with SMTP id t13so5547889ply.13 for ; Wed, 21 Nov 2018 05:27:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to:content-language:content-transfer-encoding; bh=cjtw29MPQXxO+3fR75ETwq7fRG/F9EGyMI0CKiUPsiI=; b=WM5jRn7lnAUUFoFwDXum46v6o90IxYIydEY0Wkps333DOiQvnqnVA6iMmbsoyzZnWK N0dmlHLrI6g5NyBmnHPhGjAHFOboXh2vNVD+Qs4Q0OTdR3B6FNqaPsLCgca/0WTlYn0y AhXu/Sa7AMf3ZUwyYxlaxlnDX8yuoJMAJh00x08s1RgwSz4z3r+wPPp8HHWtttm8nLGk L60jdSXRzFxMlL5wvZTc8GdTMgEfEDO2VFgpGFF7nd/0oi6B++B8t7F96VaUYG4yvIfC dlJVSs6iQTyiCDyfX/nVoV0yacKWE3ovEiRD+rAy9Votc2BxARg/MVlAUA8V4vxQoksb moww== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=cjtw29MPQXxO+3fR75ETwq7fRG/F9EGyMI0CKiUPsiI=; b=lISGLKRMJsQYlqyU5lNvpJSsmLfeWZz1rPvbr7zLXMuH2Emo6zD3glzCg6bkxZJJBu /vF7eMf/gDNLRbw3kPoGRSdQE1GVj7DrYadTG1x6p3sfkY8S7Ph43DHeMGbEd2jx+HL2 5tCmDVfzpajlfql8CQ3k5WIZeQ2nc7D3K8+3xa6pC1HS1lmSwCzQV/aB468P4rbt0fy2 awboaM6bJqx9KexYQY9TNaUlVmp8kEYyL1gPbPJGYum4MnV+Vofro+5CAi5CkesXylfD +Y8pm8jvbGFEzb9A/h9S0SRB8HdcH/ATB2fJOy+qn9tkpYtOK5i0XfRFTuWsPYXwbrV4 ZNGQ== X-Gm-Message-State: AGRZ1gLvPwHREkeJfIBWWYlkBhLtZ4QdDDHmNdcI1x81CjAZrgDpLPYX ys7/g+8QqdrxoKsaOKng9+ZXvQ== X-Google-Smtp-Source: AJdET5dTwhTQTzBotVnb8OV1yTowV3vP2QSlBH3ieQbjF/9CveXCnBJaAYJhfeAgxvSJYGUtfo5+DQ== X-Received: by 2002:a62:2292:: with SMTP id p18mr6980230pfj.9.1542806848053; Wed, 21 Nov 2018 05:27:28 -0800 (PST) Received: from [192.168.1.121] (66.29.188.166.static.utbb.net. [66.29.188.166]) by smtp.gmail.com with ESMTPSA id y6sm20495331pfl.187.2018.11.21.05.27.25 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 21 Nov 2018 05:27:26 -0800 (PST) Subject: Re: [PATCH 3/8] iomap/xfs: wire up file_operations ->iopoll() To: Benny Halevy , linux-block@vger.kernel.org, linux-aio@kvack.org, linux-fsdevel@vger.kernel.org References: <20181120171953.1258-1-axboe@kernel.dk> <20181120171953.1258-4-axboe@kernel.dk> From: Jens Axboe Message-ID: <62aca28d-fd54-ae4e-d4d4-44c7232f23da@kernel.dk> Date: Wed, 21 Nov 2018 06:27:25 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 11/21/18 2:15 AM, Benny Halevy wrote: >> +int iomap_dio_iopoll(struct kiocb *kiocb, bool spin) >> +{ >> + struct iomap_dio *dio = kiocb->private; >> + struct request_queue *q = READ_ONCE(dio->last_queue); >> + >> + if (!q || dio->cookie == BLK_QC_T_NONE) >> + return 0; >> + return blk_poll(q, READ_ONCE(dio->cookie), spin); > > How about: > blk_qc_t cookie = READ_ONCE(dio->cookie); > > if (!q || cookie == BLK_QC_T_NONE) > return 0; > return blk_poll(q, cookie, spin); > > Is there a chance the dio->cookie in the if () condition > will be stale? I've rewritten this one, more importantly it needs to guard against submission by ensuring that 'dio' is valid. -- Jens Axboe