From mboxrd@z Thu Jan 1 00:00:00 1970 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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY, 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 60DA9C3B1BF for ; Fri, 14 Feb 2020 19:47:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1D6842073A for ; Fri, 14 Feb 2020 19:47:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="YHVGfQTJ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388318AbgBNTrR (ORCPT ); Fri, 14 Feb 2020 14:47:17 -0500 Received: from aserp2120.oracle.com ([141.146.126.78]:39546 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388080AbgBNTrR (ORCPT ); Fri, 14 Feb 2020 14:47:17 -0500 Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 01EJUtgF081417; Fri, 14 Feb 2020 19:47:00 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding; s=corp-2020-01-29; bh=mRjcUyVsU+8e7lhhG/jnargLILgurytrYJr0CopghsM=; b=YHVGfQTJbe3bRbmVw8jXm6vAZFXGdlhMJy/Pq9GSKyMit5e4+x12tmjbhtRUblz3KHMB iOw8PZLob90IQcKh+2EcN2gL6ttl8Na6+Yibt361snQXaMuwahuzuPIMONtHxB9F4jm0 faPNfwYyswbBqhGkhXu/yU3pLTcEmd6Pwogp89X5SOR6i6bkifTC3aHK1MhzKR3LJJEb CaK8pWJQftObX5ZwfsZHS4CsotfMGOq18dga7tUaVltGR0GJm0Vj5Hh0vnmRP5mMEwbC f2jcpx/rzGGqPctK9Hp6WXl3l70QAZmTKo65ZWRgXq5dRhk6lPQ9O+brosbAYzp1QrDS nQ== Received: from aserp3020.oracle.com (aserp3020.oracle.com [141.146.126.70]) by aserp2120.oracle.com with ESMTP id 2y2jx6uhu3-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 14 Feb 2020 19:47:00 +0000 Received: from pps.filterd (aserp3020.oracle.com [127.0.0.1]) by aserp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 01EJRhtV111366; Fri, 14 Feb 2020 19:46:59 GMT Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by aserp3020.oracle.com with ESMTP id 2y4k3e5rf8-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 14 Feb 2020 19:46:59 +0000 Received: from abhmp0014.oracle.com (abhmp0014.oracle.com [141.146.116.20]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 01EJkv5P014768; Fri, 14 Feb 2020 19:46:57 GMT Received: from localhost.localdomain (/98.229.125.203) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 14 Feb 2020 11:46:56 -0800 From: Daniel Jordan To: Greg Kroah-Hartman , Sasha Levin Cc: Steffen Klassert , linux-kernel@vger.kernel.org, Herbert Xu , stable@vger.kernel.org, Daniel Jordan Subject: [PATCH v2 4.14] padata: Remove broken queue flushing Date: Fri, 14 Feb 2020 14:46:51 -0500 Message-Id: <20200214194651.442848-1-daniel.m.jordan@oracle.com> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200213151948.275124464@linuxfoundation.org> References: <20200213151948.275124464@linuxfoundation.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9531 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxscore=0 mlxlogscore=999 adultscore=0 bulkscore=0 malwarescore=0 phishscore=0 suspectscore=2 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002140142 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9531 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=999 malwarescore=0 priorityscore=1501 adultscore=0 phishscore=0 impostorscore=0 spamscore=0 bulkscore=0 lowpriorityscore=0 mlxscore=0 suspectscore=2 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002140142 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Herbert Xu [ Upstream commit 07928d9bfc81640bab36f5190e8725894d93b659 ] The function padata_flush_queues is fundamentally broken because it cannot force padata users to complete the request that is underway. IOW padata has to passively wait for the completion of any outstanding work. As it stands flushing is used in two places. Its use in padata_stop is simply unnecessary because nothing depends on the queues to be flushed afterwards. The other use in padata_replace is more substantial as we depend on it to free the old pd structure. This patch instead uses the pd->refcnt to dynamically free the pd structure once all requests are complete. Fixes: 2b73b07ab8a4 ("padata: Flush the padata queues actively") Cc: Signed-off-by: Herbert Xu Reviewed-by: Daniel Jordan Signed-off-by: Herbert Xu [dj: leave "pd->pinst = pinst" assignment in padata_alloc_pd()] Signed-off-by: Daniel Jordan --- kernel/padata.c | 45 ++++++++++++--------------------------------- 1 file changed, 12 insertions(+), 33 deletions(-) diff --git a/kernel/padata.c b/kernel/padata.c index 87540ce72aea..528a251217df 100644 --- a/kernel/padata.c +++ b/kernel/padata.c @@ -34,6 +34,8 @@ #define MAX_OBJ_NUM 1000 +static void padata_free_pd(struct parallel_data *pd); + static int padata_index_to_cpu(struct parallel_data *pd, int cpu_index) { int cpu, target_cpu; @@ -292,6 +294,7 @@ static void padata_serial_worker(struct work_struct *serial_work) struct padata_serial_queue *squeue; struct parallel_data *pd; LIST_HEAD(local_list); + int cnt; local_bh_disable(); squeue = container_of(serial_work, struct padata_serial_queue, work); @@ -301,6 +304,8 @@ static void padata_serial_worker(struct work_struct *serial_work) list_replace_init(&squeue->serial.list, &local_list); spin_unlock(&squeue->serial.lock); + cnt = 0; + while (!list_empty(&local_list)) { struct padata_priv *padata; @@ -310,9 +315,12 @@ static void padata_serial_worker(struct work_struct *serial_work) list_del_init(&padata->list); padata->serial(padata); - atomic_dec(&pd->refcnt); + cnt++; } local_bh_enable(); + + if (atomic_sub_and_test(cnt, &pd->refcnt)) + padata_free_pd(pd); } /** @@ -435,7 +443,7 @@ static struct parallel_data *padata_alloc_pd(struct padata_instance *pinst, setup_timer(&pd->timer, padata_reorder_timer, (unsigned long)pd); atomic_set(&pd->seq_nr, -1); atomic_set(&pd->reorder_objects, 0); - atomic_set(&pd->refcnt, 0); + atomic_set(&pd->refcnt, 1); pd->pinst = pinst; spin_lock_init(&pd->lock); @@ -460,31 +468,6 @@ static void padata_free_pd(struct parallel_data *pd) kfree(pd); } -/* Flush all objects out of the padata queues. */ -static void padata_flush_queues(struct parallel_data *pd) -{ - int cpu; - struct padata_parallel_queue *pqueue; - struct padata_serial_queue *squeue; - - for_each_cpu(cpu, pd->cpumask.pcpu) { - pqueue = per_cpu_ptr(pd->pqueue, cpu); - flush_work(&pqueue->work); - } - - del_timer_sync(&pd->timer); - - if (atomic_read(&pd->reorder_objects)) - padata_reorder(pd); - - for_each_cpu(cpu, pd->cpumask.cbcpu) { - squeue = per_cpu_ptr(pd->squeue, cpu); - flush_work(&squeue->work); - } - - BUG_ON(atomic_read(&pd->refcnt) != 0); -} - static void __padata_start(struct padata_instance *pinst) { pinst->flags |= PADATA_INIT; @@ -498,10 +481,6 @@ static void __padata_stop(struct padata_instance *pinst) pinst->flags &= ~PADATA_INIT; synchronize_rcu(); - - get_online_cpus(); - padata_flush_queues(pinst->pd); - put_online_cpus(); } /* Replace the internal control structure with a new one. */ @@ -522,8 +501,8 @@ static void padata_replace(struct padata_instance *pinst, if (!cpumask_equal(pd_old->cpumask.cbcpu, pd_new->cpumask.cbcpu)) notification_mask |= PADATA_CPU_SERIAL; - padata_flush_queues(pd_old); - padata_free_pd(pd_old); + if (atomic_dec_and_test(&pd_old->refcnt)) + padata_free_pd(pd_old); if (notification_mask) blocking_notifier_call_chain(&pinst->cpumask_change_notifier, -- 2.25.0