From patchwork Tue Dec 24 13:10:12 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yixian Liu X-Patchwork-Id: 11309333 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 76A85138D for ; Tue, 24 Dec 2019 13:10:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 558CB20706 for ; Tue, 24 Dec 2019 13:10:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726183AbfLXNKL (ORCPT ); Tue, 24 Dec 2019 08:10:11 -0500 Received: from szxga04-in.huawei.com ([45.249.212.190]:8176 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726213AbfLXNKL (ORCPT ); Tue, 24 Dec 2019 08:10:11 -0500 Received: from DGGEMS404-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id D76909E1F0072F25B993; Tue, 24 Dec 2019 21:10:08 +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; Tue, 24 Dec 2019 21:10:01 +0800 From: Yixian Liu To: , , CC: , Subject: [PATCH v4 for-next 0/2] Fix crash due to sleepy mutex while holding lock in post_{send|recv|poll} Date: Tue, 24 Dec 2019 21:10:12 +0800 Message-ID: <1577193014-42646-1-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 workqueue 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} v4 changes: 1. Add flag for PI is being pushed according to Jason's suggestion to reduce unnecessary works submitted to workqueue. 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 | 4 ++ drivers/infiniband/hw/hns/hns_roce_hw_v2.c | 98 +++++++++++++++-------------- drivers/infiniband/hw/hns/hns_roce_qp.c | 45 +++++++++++++ 3 files changed, 99 insertions(+), 48 deletions(-)