From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <SRS0=HuTb=YA=vger.kernel.org=linux-block-owner@kernel.org>
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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,
	MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 6B747C352AA
	for <linux-block@archiver.kernel.org>; Mon,  7 Oct 2019 10:23:35 +0000 (UTC)
Received: from vger.kernel.org (vger.kernel.org [209.132.180.67])
	by mail.kernel.org (Postfix) with ESMTP id 3BDD1206BB
	for <linux-block@archiver.kernel.org>; Mon,  7 Oct 2019 10:23:35 +0000 (UTC)
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1727252AbfJGKXe (ORCPT <rfc822;linux-block@archiver.kernel.org>);
        Mon, 7 Oct 2019 06:23:34 -0400
Received: from szxga06-in.huawei.com ([45.249.212.32]:60076 "EHLO huawei.com"
        rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP
        id S1726010AbfJGKXe (ORCPT <rfc822;linux-block@vger.kernel.org>);
        Mon, 7 Oct 2019 06:23:34 -0400
Received: from DGGEMS404-HUB.china.huawei.com (unknown [172.30.72.60])
        by Forcepoint Email with ESMTP id 2ACC1B3DC1ABF75E4C3E;
        Mon,  7 Oct 2019 18:23:32 +0800 (CST)
Received: from [127.0.0.1] (10.202.227.179) by DGGEMS404-HUB.china.huawei.com
 (10.3.19.204) with Microsoft SMTP Server id 14.3.439.0; Mon, 7 Oct 2019
 18:23:27 +0800
Subject: Re: [PATCH V2 RESEND 3/5] blk-mq: stop to handle IO before hctx's all
 CPUs become offline
To:     Ming Lei <ming.lei@redhat.com>, Jens Axboe <axboe@kernel.dk>
References: <20191006024516.19996-1-ming.lei@redhat.com>
 <20191006024516.19996-4-ming.lei@redhat.com>
CC:     <linux-block@vger.kernel.org>,
        Bart Van Assche <bvanassche@acm.org>,
        Hannes Reinecke <hare@suse.com>,
        Christoph Hellwig <hch@lst.de>,
        "Thomas Gleixner" <tglx@linutronix.de>,
        Keith Busch <keith.busch@intel.com>
From:   John Garry <john.garry@huawei.com>
Message-ID: <047ecdf1-bd4b-6702-1add-83b902a6902f@huawei.com>
Date:   Mon, 7 Oct 2019 11:23:22 +0100
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101
 Thunderbird/45.3.0
MIME-Version: 1.0
In-Reply-To: <20191006024516.19996-4-ming.lei@redhat.com>
Content-Type: text/plain; charset="windows-1252"; format=flowed
Content-Transfer-Encoding: 7bit
X-Originating-IP: [10.202.227.179]
X-CFilter-Loop: Reflected
Sender: linux-block-owner@vger.kernel.org
Precedence: bulk
List-ID: <linux-block.vger.kernel.org>
X-Mailing-List: linux-block@vger.kernel.org

On 06/10/2019 03:45, Ming Lei wrote:
> +	}
> +}
> +
> +static int blk_mq_hctx_notify_online(unsigned int cpu, struct hlist_node *node)
> +{
> +	struct blk_mq_hw_ctx *hctx = hlist_entry_safe(node,
> +			struct blk_mq_hw_ctx, cpuhp_online);
> +	unsigned prev_cpu = -1;
> +
> +	while (true) {
> +		unsigned next_cpu = cpumask_next_and(prev_cpu, hctx->cpumask,
> +				cpu_online_mask);
> +
> +		if (next_cpu >= nr_cpu_ids)
> +			break;
> +
> +		/* return if there is other online CPU on this hctx */
> +		if (next_cpu != cpu)
> +			return 0;
> +
> +		prev_cpu = next_cpu;
> +	}
> +
> +	set_bit(BLK_MQ_S_INTERNAL_STOPPED, &hctx->state);
> +	blk_mq_drain_inflight_rqs(hctx);
> +

Does this do the same:

{
	struct blk_mq_hw_ctx *hctx = hlist_entry_safe(node,
			struct blk_mq_hw_ctx, cpuhp_online);
	cpumask_var_t tmp;

	cpumask_and(tmp, hctx->cpumask, cpu_online_mask);

	/* test if there is any other cpu online in the hctx cpu mask */
	if (cpumask_any_but(tmp, cpu) < nr_cpu_ids)
		return 0;

	set_bit(BLK_MQ_S_INTERNAL_STOPPED, &hctx->state);
	blk_mq_drain_inflight_rqs(hctx);

	return 0;
}

If so, it's more readable and concise.

Thanks,
John


BTW, You could have added my Tested-by tags...

> +	return 0;
> +}
> +