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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A2C2EE7F14B for ; Wed, 27 Sep 2023 01:49:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235204AbjI0BtM (ORCPT ); Tue, 26 Sep 2023 21:49:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37980 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234484AbjI0BrI (ORCPT ); Tue, 26 Sep 2023 21:47:08 -0400 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BEC6ACF7; Tue, 26 Sep 2023 17:54:59 -0700 (PDT) Received: from mail02.huawei.com (unknown [172.30.67.143]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4RwJ6l5pMzz4f3k6X; Wed, 27 Sep 2023 08:54:55 +0800 (CST) Received: from [10.174.176.73] (unknown [10.174.176.73]) by APP4 (Coremail) with SMTP id gCh0CgDHXd1ffRNlJNruBQ--.41325S3; Wed, 27 Sep 2023 08:54:56 +0800 (CST) Subject: Re: [PATCH v2 1/2] md: factor out a new helper to put mddev To: Song Liu , Yu Kuai Cc: mariusz.tkaczyk@linux.intel.com, xni@redhat.com, linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org, yi.zhang@huawei.com, yangerkun@huawei.com, "yukuai (C)" References: <20230926025827.671407-1-yukuai1@huaweicloud.com> <20230926025827.671407-2-yukuai1@huaweicloud.com> From: Yu Kuai Message-ID: <94ef3ef4-0580-416b-f672-250a91b39e10@huaweicloud.com> Date: Wed, 27 Sep 2023 08:54:54 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit X-CM-TRANSID: gCh0CgDHXd1ffRNlJNruBQ--.41325S3 X-Coremail-Antispam: 1UD129KBjvJXoW7ArWxWF48Kw1rXFy5GF17Jrb_yoW8Zr1Dpa ySqa90kr4DXFy3W39rZanru3WYqws2grWktryfKwn8ZFy5Wr1DWw1Fgws5Wr1DAw1fJFs0 v3WUK3y7Cr1UtrDanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUkG14x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26F1j6w1UM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26F4j 6r4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oV Cq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0 I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r 4UM4x0Y48IcVAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwCYjI0SjxkI62AI1cAE67vI Y487MxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI 0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUtVW8ZwCIc40Y 0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxV WUJVW8JwCI42IY6xAIw20EY4v20xvaj40_WFyUJVCq3wCI42IY6I8E87Iv67AKxVWUJVW8 JwCI42IY6I8E87Iv6xkF7I0E14v26r1j6r4UYxBIdaVFxhVjvjDU0xZFpf9x0JUdHUDUUU UU= X-CM-SenderInfo: 51xn3trlr6x35dzhxuhorxvhhfrp/ X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-raid@vger.kernel.org Hi, 在 2023/09/27 8:15, Song Liu 写道: > On Mon, Sep 25, 2023 at 8:04 PM Yu Kuai wrote: >> >> From: Yu Kuai >> >> There are no functional changes, the new helper will still hold >> 'all_mddevs_lock' after putting mddev, and it will be used to simplify >> md_seq_ops. >> >> Signed-off-by: Yu Kuai >> --- >> drivers/md/md.c | 18 +++++++++++++++--- >> 1 file changed, 15 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/md/md.c b/drivers/md/md.c >> index 10cb4dfbf4ae..a5ef6f7da8ec 100644 >> --- a/drivers/md/md.c >> +++ b/drivers/md/md.c >> @@ -616,10 +616,15 @@ static inline struct mddev *mddev_get(struct mddev *mddev) >> >> static void mddev_delayed_delete(struct work_struct *ws); >> >> -void mddev_put(struct mddev *mddev) >> +static void __mddev_put(struct mddev *mddev, bool locked) >> { >> - if (!atomic_dec_and_lock(&mddev->active, &all_mddevs_lock)) >> + if (locked) { >> + spin_lock(&all_mddevs_lock); >> + if (!atomic_dec_and_test(&mddev->active)) >> + return; >> + } else if (!atomic_dec_and_lock(&mddev->active, &all_mddevs_lock)) >> return; >> + > > This condition is indeed very confusing. No matter whether we call the > flag "locked" or "do_lock", it is not really accurate. > > How about we factor out a helper with the following logic: > > if (!mddev->raid_disks && list_empty(&mddev->disks) && > mddev->ctime == 0 && !mddev->hold_active) { > /* Array is not configured at all, and not held active, > * so destroy it */ > set_bit(MD_DELETED, &mddev->flags); > > /* > * Call queue_work inside the spinlock so that > * flush_workqueue() after mddev_find will succeed in waiting > * for the work to be done. > */ > queue_work(md_misc_wq, &mddev->del_work); > } > > and then use it at the two callers? > > Does this make sense? Yes, that sounds great. I'll do this in v3. Thanks, Kuai > > Thanks, > Song > . >