From patchwork Thu Nov 21 11:19:58 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yixian Liu X-Patchwork-Id: 11256113 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1C05313A4 for ; Thu, 21 Nov 2019 11:19:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 06986208A3 for ; Thu, 21 Nov 2019 11:19:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726881AbfKULTl (ORCPT ); Thu, 21 Nov 2019 06:19:41 -0500 Received: from szxga05-in.huawei.com ([45.249.212.191]:6262 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726293AbfKULTl (ORCPT ); Thu, 21 Nov 2019 06:19:41 -0500 Received: from DGGEMS404-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 424B8857199527613F4E; Thu, 21 Nov 2019 19:19:37 +0800 (CST) Received: from localhost.localdomain (10.69.192.56) by DGGEMS404-HUB.china.huawei.com (10.3.19.204) with Microsoft SMTP Server id 14.3.439.0; Thu, 21 Nov 2019 19:19:30 +0800 From: Yixian Liu To: , , CC: , Subject: [PATCH v3 for-next 0/2] Fix crash due to sleepy mutex while holding lock in post_{send|recv|poll} Date: Thu, 21 Nov 2019 19:19:58 +0800 Message-ID: <1574335200-34923-1-git-send-email-liuyixian@huawei.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 X-Originating-IP: [10.69.192.56] X-CFilter-Loop: Reflected Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org Earlier Background: HiP08 RoCE hardware lacks ability(a known hardware problem) to flush outstanding WQEs if QP state gets into errored mode for some reason. To overcome this hardware problem and as a workaround, when QP is detected to be in errored state during various legs like post send, post receive etc [1], flush needs to be performed from the driver. These data-path legs might get called concurrently from various context, like thread and interrupt as well (like NVMe driver). Hence, these need to be protected with spin-locks for the concurrency. This code exists within the driver. Problem: Earlier The patch[1] sent to solve the hardware limitation explained in the background section had a bug in the software flushing leg. It acquired mutex while modifying QP state to errored state and while conveying it to the hardware using the mailbox. This caused leg to sleep while holding spin-lock and caused crash. Suggested Solution: In this patch, we have proposed to defer the flushing of the QP in Errored state using the workqueue. We do understand that this might have an impact on the recovery times as scheduling of the wqorkqueue handler depends upon the occupancy of the system. Therefore to roughly mitigate this affect we have tried to use Concurrency Managed workqueue to give worker thread (and hence handler) a chance to run over more than one core. [1] https://patchwork.kernel.org/patch/10534271/ This patch-set consists of: [Patch 001] Introduce workqueue based WQE Flush Handler [Patch 002] Call WQE flush handler in post {send|receive|poll} v3 changes: 1. Fall back to dynamically allocate flush_work. v2 changes: 1. Remove new created workqueue according to Jason's comment 2. Remove dynamic allocation for flush_work according to Jason's comment 3. Change current irq singlethread workqueue to concurrency management workqueue to ensure work unblocked. Yixian Liu (2): RDMA/hns: Add the workqueue framework for flush cqe handler RDMA/hns: Delayed flush cqe process with workqueue drivers/infiniband/hw/hns/hns_roce_device.h | 2 + drivers/infiniband/hw/hns/hns_roce_hw_v2.c | 88 +++++++++++++---------------- drivers/infiniband/hw/hns/hns_roce_qp.c | 43 ++++++++++++++ 3 files changed, 85 insertions(+), 48 deletions(-)