From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from dggsgout12.his.huawei.com (dggsgout12.his.huawei.com [45.249.212.56]) (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 395C7125A9; Fri, 15 Aug 2025 01:32:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755221549; cv=none; b=anCmmRvr7U56bqsliysCpFaUHBTZcMMudkJ3E9Q8p92p77KjwPmlNd6UZjeHn+QaIijSpWfztE2XdhUeHBdE8mlFV78D8rvYjrfeFOboD7M29VXEGsUjwlswFGr4ez9JHxsqcl1zk92rMAmcGm8iQ3H+FT0iWYi/kURFb14Ynw0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755221549; c=relaxed/simple; bh=vEXFWBWqeNLLUnrpTboM3dHS9/dfw8xwNUJxGm1EiZg=; h=Subject:To:Cc:References:From:Message-ID:Date:MIME-Version: In-Reply-To:Content-Type; b=lvTEL0646hbo7pAaxkXavjUw2ad0QSftZY2Q5fdoom7XYo3BP9uA592dc3xaT4moVtMzZniSc4KskurFsqYoohFuBXB9ey8DMQHfrRzTQlT/9etkYI8FET29YIuldU7t31BRhlIXT1kHr7TazrsF0q/+gXraOJdr7OqwzIWwHxw= 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=45.249.212.56 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 [172.19.163.216]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTPS id 4c34NS18cLzKHMvF; Fri, 15 Aug 2025 09:32:24 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id 766CB1A1511; Fri, 15 Aug 2025 09:32:23 +0800 (CST) Received: from [10.174.179.143] (unknown [10.174.179.143]) by APP4 (Coremail) with SMTP id gCh0CgDnYhMmjp5oGnTfDg--.26725S3; Fri, 15 Aug 2025 09:32:23 +0800 (CST) Subject: Re: [PATCH 03/16] blk-mq: remove useless checkings from blk_mq_update_nr_requests() To: Nilay Shroff , Yu Kuai , axboe@kernel.dk, bvanassche@acm.org, hare@suse.de, ming.lei@redhat.com Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, yi.zhang@huawei.com, yangerkun@huawei.com, johnny.chenyi@huawei.com, "yukuai (C)" References: <20250814033522.770575-1-yukuai1@huaweicloud.com> <20250814033522.770575-4-yukuai1@huaweicloud.com> <97b63163-a122-48f0-805a-a06cf792903f@linux.ibm.com> From: Yu Kuai Message-ID: <31a567ac-180a-b2de-2233-e758a9a977d8@huaweicloud.com> Date: Fri, 15 Aug 2025 09:32:22 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.9.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <97b63163-a122-48f0-805a-a06cf792903f@linux.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit X-CM-TRANSID:gCh0CgDnYhMmjp5oGnTfDg--.26725S3 X-Coremail-Antispam: 1UD129KBjvJXoW7Aw1fKw17Xr4xuFWUuw4UArb_yoW8AFWfpa y3Ga12k340qr42kas2qanrXa47Kr4kAr1xCr43t3WayryDKFnFvr1rJw4UWryIvrs3Aw4x GF4UArZFvw1kZFDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBF14x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26w1j6s0DM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4U JVWxJr1l84ACjcxK6I8E87Iv67AKxVW0oVCq3wA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_Gc CE3s1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E 2Ix0cI8IcVAFwI0_Jrv_JF1lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWUJV W8JwACjcxG0xvEwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1lFIxGxcIEc7CjxVA2Y2ka 0xkIwI1lc7I2V7IY0VAS07AlzVAYIcxG8wCY1x0262kKe7AKxVWUtVW8ZwCF04k20xvY0x 0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E 7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_Jw0_GFylIxkGc2Ij64vIr41lIxAIcV C0I7IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAFwI0_Gr0_Cr1lIxAIcVCF 04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7 CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x0JUpwZcUUUUU= X-CM-SenderInfo: 51xn3trlr6x35dzhxuhorxvhhfrp/ Hi, 在 2025/08/14 20:23, Nilay Shroff 写道: > > > On 8/14/25 9:05 AM, Yu Kuai wrote: >> From: Yu Kuai >> >> 1) queue_requests_store() is the only caller of >> blk_mq_update_nr_requests(), where queue is already freezed, no need to >> check mq_freeze_depth; >> 2) q->tag_set must be set for request_based device, and queue_is_mq() is >> already checked in blk_mq_queue_attr_visible(), no need to check >> q->tag_set. >> 3) During initialization, hctx->tags in initialized before queue >> kobject, and during del_gendisk, queue kobject is deleted before >> exiting hctx, hence checking hctx->tags is useless. >> >> Signed-off-by: Yu Kuai >> --- >> block/blk-mq.c | 11 +---------- >> 1 file changed, 1 insertion(+), 10 deletions(-) >> >> diff --git a/block/blk-mq.c b/block/blk-mq.c >> index b67d6c02eceb..3a219b7b3688 100644 >> --- a/block/blk-mq.c >> +++ b/block/blk-mq.c >> @@ -4921,24 +4921,15 @@ int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr) >> { >> struct blk_mq_tag_set *set = q->tag_set; >> struct blk_mq_hw_ctx *hctx; >> - int ret; >> + int ret = 0; >> unsigned long i; >> >> - if (WARN_ON_ONCE(!q->mq_freeze_depth)) >> - return -EINVAL; >> - >> - if (!set) >> - return -EINVAL; >> - >> if (q->nr_requests == nr) >> return 0; >> >> blk_mq_quiesce_queue(q); >> >> - ret = 0; >> queue_for_each_hw_ctx(q, hctx, i) { >> - if (!hctx->tags) >> - continue; > It's possible that hctx->tags is set to NULL in case no software > queues are mapped to the hardware queue. So it seems that this > check is valid. Please see blk_mq_map_swqueue(). Ok, thanks for the reviw. I didn't notice this, just wonder how can this happen? nr_hw_queues > NR_CPUS? Thanks, Kuai > > Thanks, > --Nilay > > . >