From patchwork Tue Sep 7 14:01:50 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Kuai X-Patchwork-Id: 12478789 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 9E759C433F5 for ; Tue, 7 Sep 2021 13:52:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 83D7860F70 for ; Tue, 7 Sep 2021 13:52:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231224AbhIGNxK (ORCPT ); Tue, 7 Sep 2021 09:53:10 -0400 Received: from szxga03-in.huawei.com ([45.249.212.189]:15303 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229759AbhIGNxK (ORCPT ); Tue, 7 Sep 2021 09:53:10 -0400 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.57]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4H3ms05rp7z8sss; Tue, 7 Sep 2021 21:51:32 +0800 (CST) Received: from dggema762-chm.china.huawei.com (10.1.198.204) by dggemv703-chm.china.huawei.com (10.3.19.46) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2308.8; Tue, 7 Sep 2021 21:52:01 +0800 Received: from huawei.com (10.175.127.227) by dggema762-chm.china.huawei.com (10.1.198.204) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2308.8; Tue, 7 Sep 2021 21:52:01 +0800 From: Yu Kuai To: , , CC: , , , , Subject: [PATCH v4 2/6] nbd: convert to use blk_mq_find_and_get_req() Date: Tue, 7 Sep 2021 22:01:50 +0800 Message-ID: <20210907140154.2134091-3-yukuai3@huawei.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210907140154.2134091-1-yukuai3@huawei.com> References: <20210907140154.2134091-1-yukuai3@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.127.227] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggema762-chm.china.huawei.com (10.1.198.204) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org blk_mq_tag_to_rq() can only ensure to return valid request in following situation: 1) client send request message to server first submit_bio ... blk_mq_get_tag ... blk_mq_get_driver_tag ... nbd_queue_rq nbd_handle_cmd nbd_send_cmd 2) client receive respond message from server recv_work nbd_read_stat blk_mq_tag_to_rq If step 1) is missing, blk_mq_tag_to_rq() will return a stale request, which might be freed. Thus convert to use blk_mq_find_and_get_req() to make sure the returned request is not freed. However, there are still some problems if the request is started, and this will be fixed in next patch. Signed-off-by: Yu Kuai --- drivers/block/nbd.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 5170a630778d..920da390635c 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -718,12 +718,13 @@ static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index) tag = nbd_handle_to_tag(handle); hwq = blk_mq_unique_tag_to_hwq(tag); if (hwq < nbd->tag_set.nr_hw_queues) - req = blk_mq_tag_to_rq(nbd->tag_set.tags[hwq], - blk_mq_unique_tag_to_tag(tag)); + req = blk_mq_find_and_get_req(nbd->tag_set.tags[hwq], + blk_mq_unique_tag_to_tag(tag)); if (!req || !blk_mq_request_started(req)) { dev_err(disk_to_dev(nbd->disk), "Unexpected reply (%d) %p\n", tag, req); - return ERR_PTR(-ENOENT); + ret = -ENOENT; + goto put_req; } trace_nbd_header_received(req, handle); cmd = blk_mq_rq_to_pdu(req); @@ -785,6 +786,9 @@ static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index) out: trace_nbd_payload_received(req, handle); mutex_unlock(&cmd->lock); +put_req: + if (req) + blk_mq_put_rq_ref(req); return ret ? ERR_PTR(ret) : cmd; }