Received: by 2002:a05:7412:d1aa:b0:fc:a2b0:25d7 with SMTP id ba42csp399146rdb; Mon, 29 Jan 2024 05:56:16 -0800 (PST) X-Google-Smtp-Source: AGHT+IEFRQztHesa14nQyS4gJLK2EUy3w94L38QolxB9MNzGkII9EwcN+DiCDtGqP8w8MR0wsvqV X-Received: by 2002:a05:620a:470f:b0:784:164:c817 with SMTP id bs15-20020a05620a470f00b007840164c817mr1194399qkb.146.1706536575890; Mon, 29 Jan 2024 05:56:15 -0800 (PST) ARC-Seal: i=2; a=rsa-sha256; t=1706536575; cv=pass; d=google.com; s=arc-20160816; b=exml3p7PkJ77E/c+/cuztha9uDEYZQOqLKZ72uDBZS7F8Ekyd5I6cA0frEi4ct+I/q yYL0xGIDe2BiRjO3cf+Mr8+sh2AGJtubMGuCDv7X70RJUnawi25qth2bgXXgm2f1cLBF +qr9bGBDJv3LFvMVPpUSHIxtYO9eb4jhd3S1qFL5PaBnyPsHvtSYP1A3JNNW6eNtTRk/ duKSc1YIEt7SFkzfX5fndZvlawNTl6DyER15d8Yh6DtdJfyAJqt81J6EhllEH/L0atsN B8oS6zyV2jeRDuuOLQW6d45u9GKdKFXR6r1QNVsmeUvmh6Z1fAqtnifnYjoG0t3E5GeS 2i7Q== ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:in-reply-to:from:references:cc:to:subject :user-agent:mime-version:list-unsubscribe:list-subscribe:list-id :precedence:date:message-id; bh=2NhSQO0vOhXTl5AnYZG3Db64BU0SnGY1M3Vocju1qFA=; fh=+fNXhwvZnAGyWndvMFAEZ8mba542wd2AKbKE7pZFeX4=; b=DCywgviNIz6+eFWNssbp7xSRiS4/8m6HdM1IpKAnw76wYvb3ltZQhE7g6Zo+vj3Any TlxdLmv3IZYDwWow53lsYLZhIR5Dje3i0qOIeaCOA84Y/hmSTa2twXLjZCLjUd+8STp8 Ahbh8uDRRcTNGbzUjf7rdf/Fiv3xQoosoRGY/xrbvwSWbfnwOT5/2cZ29hX9bTMrjDei A/tmUIC00nqU6CgHhKDAXRl90uDHx71FZievg3m3HeX96yaJtvSJNgWbTazkPIRlemki 2CSfDW7t4TNXxPHpZqe4FYg/H+QlmtiKivH/rlop185T95T++yZA+Dbq6953NY/a5T9F ZSww== ARC-Authentication-Results: i=2; mx.google.com; arc=pass (i=1 spf=pass spfdomain=huaweicloud.com); spf=pass (google.com: domain of linux-kernel+bounces-42839-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45d1:ec00::1 as permitted sender) smtp.mailfrom="linux-kernel+bounces-42839-linux.lists.archive=gmail.com@vger.kernel.org" Return-Path: Received: from ny.mirrors.kernel.org (ny.mirrors.kernel.org. [2604:1380:45d1:ec00::1]) by mx.google.com with ESMTPS id c15-20020a05620a134f00b00784030d46ddsi982917qkl.496.2024.01.29.05.56.15 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 29 Jan 2024 05:56:15 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel+bounces-42839-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45d1:ec00::1 as permitted sender) client-ip=2604:1380:45d1:ec00::1; Authentication-Results: mx.google.com; arc=pass (i=1 spf=pass spfdomain=huaweicloud.com); spf=pass (google.com: domain of linux-kernel+bounces-42839-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45d1:ec00::1 as permitted sender) smtp.mailfrom="linux-kernel+bounces-42839-linux.lists.archive=gmail.com@vger.kernel.org" Received: from smtp.subspace.kernel.org (wormhole.subspace.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ny.mirrors.kernel.org (Postfix) with ESMTPS id F37F21C24BE3 for ; Mon, 29 Jan 2024 13:55:56 +0000 (UTC) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 59CE0657CC; Mon, 29 Jan 2024 13:55:47 +0000 (UTC) Received: from dggsgout11.his.huawei.com (unknown [45.249.212.51]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6A99E657AF; Mon, 29 Jan 2024 13:55:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.51 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706536546; cv=none; b=juE+fWcNutrywctvm2cEo7qIOeHQtDRZJ9Iko5XzILNqH8po+iH7ISNauydPPom4vh+gg/jcoy/vfWFMXPVu57ONM4Kj+K3RmTvSe7b9kR+aptyFf9+D/bhokVNn6jo3rJhp/XoTHRmtCCTDtqFPTA9mUqg57bLJTB8FgTSohbI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706536546; c=relaxed/simple; bh=Mu1POmJQZVm0NHymvBVIB8/NOZC6MGmOcANeEI54nU4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=q/NUF8bLjUc4BgUsn/mnQl9g2lFQZZcUbZdTslrpSIsi8A3hmYXOZCxZx3idjMtoS29HfHUU2KwQk0rY+o6iI6rrKolX0S6Qlvi4KSSBwt1pDoMvxKx0oy+5oyLThGaSLabBcQjgrh4WBCqKIw2ZSvS/XP+d7kEmQITaaPq/hbk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.51 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.235]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4TNqZK2CD5z4f3jHm; Mon, 29 Jan 2024 21:55:37 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.112]) by mail.maildlp.com (Postfix) with ESMTP id C99491A0232; Mon, 29 Jan 2024 21:55:39 +0800 (CST) Received: from [10.174.179.155] (unknown [10.174.179.155]) by APP1 (Coremail) with SMTP id cCh0CgBnOBFbrrdlZHhrCQ--.18903S3; Mon, 29 Jan 2024 21:55:39 +0800 (CST) Message-ID: Date: Mon, 29 Jan 2024 21:55:39 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:104.0) Gecko/20100101 Thunderbird/104.0 Subject: Re: [PATCH] md: get rdev->mddev with READ_ONCE() To: song@kernel.org Cc: linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org, yukuai3@huawei.com, linan122@huawei.com, yi.zhang@huawei.com, yangerkun@huawei.com, lilingfeng3@huawei.com References: <20231229070500.3602712-1-lilingfeng@huaweicloud.com> From: Li Lingfeng In-Reply-To: <20231229070500.3602712-1-lilingfeng@huaweicloud.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-CM-TRANSID:cCh0CgBnOBFbrrdlZHhrCQ--.18903S3 X-Coremail-Antispam: 1UD129KBjvJXoW7Ww1Uuw43uF1xCF1xXr1rXrb_yoW8JFWrp3 yrXFy5Wr1Yv3y5Cw4UZFWkua4Fqwn3KrZFkry3u34rZ3WjqwnxKF1UWa4DJFyrZanrur4x Xa17Xan8Z3sIgrUanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUyCb4IE77IF4wAFF20E14v26r4j6ryUM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4 vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Xr0_Ar1l84ACjcxK6xIIjxv20xvEc7Cj xVAFwI0_Gr0_Cr1l84ACjcxK6I8E87Iv67AKxVW0oVCq3wA2z4x0Y4vEx4A2jsIEc7CjxV AFwI0_GcCE3s1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2 j2WlYx0E2Ix0cI8IcVAFwI0_Jrv_JF1lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7x kEbVWUJVW8JwACjcxG0xvEwIxGrwCYjI0SjxkI62AI1cAE67vIY487MxAIw28IcxkI7VAK I48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7 xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUtVW8ZwCIc40Y0x0EwIxGrwCI42IY6xII jxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxVWUJVW8JwCI42IY6xAIw2 0EY4v20xvaj40_WFyUJVCq3wCI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF 7I0E14v26r1j6r4UYxBIdaVFxhVjvjDU0xZFpf9x07UGYL9UUUUU= X-CM-SenderInfo: polox0xjih0w46kxt4xhlfz01xgou0bp/ Friendly ping ... Thanks 在 2023/12/29 15:05, Li Lingfeng 写道: > From: Li Lingfeng > > Users may get rdev->mddev by sysfs while rdev is releasing. > So use both READ_ONCE() and WRITE_ONCE() to prevent load/store tearing > and to read/write mddev atomically. > > Signed-off-by: Li Lingfeng > --- > drivers/md/md.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/md/md.c b/drivers/md/md.c > index 9bdd57324c37..3b38a565bffa 100644 > --- a/drivers/md/md.c > +++ b/drivers/md/md.c > @@ -2562,7 +2562,7 @@ static void md_kick_rdev_from_array(struct md_rdev *rdev) > list_del_rcu(&rdev->same_set); > pr_debug("md: unbind<%pg>\n", rdev->bdev); > mddev_destroy_serial_pool(rdev->mddev, rdev); > - rdev->mddev = NULL; > + WRITE_ONCE(rdev->mddev, NULL); > sysfs_remove_link(&rdev->kobj, "block"); > sysfs_put(rdev->sysfs_state); > sysfs_put(rdev->sysfs_unack_badblocks); > @@ -3646,7 +3646,7 @@ rdev_attr_store(struct kobject *kobj, struct attribute *attr, > struct kernfs_node *kn = NULL; > bool suspend = false; > ssize_t rv; > - struct mddev *mddev = rdev->mddev; > + struct mddev *mddev = READ_ONCE(rdev->mddev); > > if (!entry->store) > return -EIO;