From patchwork Thu Jul 29 12:38:21 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 488781 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=-19.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, 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 64FA8C4338F for ; Thu, 29 Jul 2021 12:38:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 484E560F21 for ; Thu, 29 Jul 2021 12:38:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237004AbhG2Mi0 (ORCPT ); Thu, 29 Jul 2021 08:38:26 -0400 Received: from mail.kernel.org ([198.145.29.99]:38724 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234459AbhG2MiZ (ORCPT ); Thu, 29 Jul 2021 08:38:25 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 32A7D60F12; Thu, 29 Jul 2021 12:38:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1627562302; bh=vfuS3bxTIxzEpJezHgFBzDO0lgYY5VSG8HI2HfXHmoc=; h=From:To:Cc:Subject:Date:From; b=snkSsBf8HKOTb5d+Rj5uj7lRs7T5bBzz+QRPrqnaUIe5xgHntOzMDkDWsAhm4ft3J OF8HIGgGIdIZHRr0bFNXTbvvgD4MITf+o4h3kfAbo0jxgO+ZHnmA8yZT4UtnrDN00C ijFbn6+JYwJr34rRSvcNQYeBXX4ZUn4eP59w2q3jnk4qi9Iq1Es12JvkXyNzwe+nvb Eets4gw+0AJLjpIqYteIOKM86nifKigd9Cz/ymvE3+kmhK85nOtThUglun7lYUVGMN qyPlelLjo+TLgCxRpEQllCN8tUxYVZePmA9xr5bcYWqlFUQD5+orhOBzaBDIIGngIG lXhd8V9qpVyxQ== From: Jeff Layton To: ceph-devel@vger.kernel.org Cc: idryomov@gmail.com, Xiubo Li Subject: [PATCH v2] ceph: cancel delayed work instead of flushing on mdsc teardown Date: Thu, 29 Jul 2021 08:38:21 -0400 Message-Id: <20210729123821.100086-1-jlayton@kernel.org> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: ceph-devel@vger.kernel.org The first thing metric_delayed_work does is check mdsc->stopping, and then return immediately if it's set. That's good since we would have already torn down the metric structures at this point, otherwise, but there is no locking around mdsc->stopping. It's possible that the ceph_metric_destroy call could race with the delayed_work, in which case we could end up with the delayed_work accessing destroyed percpu variables. At this point in the mdsc teardown, the "stopping" flag has already been set, so there's no benefit to flushing the work. Move the work cancellation in ceph_metric_destroy ahead of the percpu variable destruction, and eliminate the flush_delayed_work call in ceph_mdsc_destroy. Cc: Xiubo Li Fixes: 18f473b384a6 ("ceph: periodically send perf metrics to MDSes") Signed-off-by: Jeff Layton --- fs/ceph/mds_client.c | 1 - fs/ceph/metric.c | 4 ++-- 2 files changed, 2 insertions(+), 3 deletions(-) v2: just drop the flush call altogether and move the cancel before the percpu variables are destroyed (per Xiubo's suggestion). diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c index c43091a30ba8..34124fb1605e 100644 --- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -4979,7 +4979,6 @@ void ceph_mdsc_destroy(struct ceph_fs_client *fsc) ceph_metric_destroy(&mdsc->metric); - flush_delayed_work(&mdsc->metric.delayed_work); fsc->mdsc = NULL; kfree(mdsc); dout("mdsc_destroy %p done\n", mdsc); diff --git a/fs/ceph/metric.c b/fs/ceph/metric.c index 5ac151eb0d49..04d5df29bbbf 100644 --- a/fs/ceph/metric.c +++ b/fs/ceph/metric.c @@ -302,6 +302,8 @@ void ceph_metric_destroy(struct ceph_client_metric *m) if (!m) return; + cancel_delayed_work_sync(&m->delayed_work); + percpu_counter_destroy(&m->total_inodes); percpu_counter_destroy(&m->opened_inodes); percpu_counter_destroy(&m->i_caps_mis); @@ -309,8 +311,6 @@ void ceph_metric_destroy(struct ceph_client_metric *m) percpu_counter_destroy(&m->d_lease_mis); percpu_counter_destroy(&m->d_lease_hit); - cancel_delayed_work_sync(&m->delayed_work); - ceph_put_mds_session(m->session); }