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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 3BBECC352A4 for ; Fri, 7 Feb 2020 08:46:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1301921741 for ; Fri, 7 Feb 2020 08:46:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581065206; bh=g9SrhGvzn/0L5RyKMhVNFT5H0ZJLAOL4KnvytsXZq8A=; h=Subject:To:Cc:From:Date:List-ID:From; b=b5tBSLh6GVM/pdEuLYfDC4PBbkXWkN0Ga7T2RM/9lwH643Vu51XlxUAZKj6Q3SwjT CjEk2KqRegsh5SVSmPoM+XBWldzycG1WTH0Cd/0AmM0ZG97uC6TnnEyHjNczx2NIG6 lu0aCtFoWWzohOmPopkA9B1dgJ9dVWxRKGh+wq28= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726619AbgBGIqp (ORCPT ); Fri, 7 Feb 2020 03:46:45 -0500 Received: from out2-smtp.messagingengine.com ([66.111.4.26]:37257 "EHLO out2-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726451AbgBGIqp (ORCPT ); Fri, 7 Feb 2020 03:46:45 -0500 Received: from compute6.internal (compute6.nyi.internal [10.202.2.46]) by mailout.nyi.internal (Postfix) with ESMTP id A7E2621B55; Fri, 7 Feb 2020 03:46:44 -0500 (EST) Received: from mailfrontend1 ([10.202.2.162]) by compute6.internal (MEProxy); Fri, 07 Feb 2020 03:46:44 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:from:message-id:mime-version:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm2; bh=82SqsV ph7Ky/Rafs6WDHHZq0M0UeB7TrQyzUbLl0Frw=; b=VyOVNnQu40+zUpqBHEB2Zh TLLnCOCOtxED3qmW6yUTEwasRxu1Lpl3OYRL/XRf4c0VwqmxZWqoXeRs6a5fJvls PY0/zhLoBLMARBJcMHFFi5CZ8Gd+FLhzeFJJS9ow9UHJvpNyG43d7bUhKIJddtOH ZuE51v/DVz9NBOCSUEDV5qHIMM/ZrHY7HEM+Hw/U0bA8fMODt69pechXQjq/etK9 1MEjglrHBxL+87jQx2/yT9uCJt9VRFNbys7GBVGEntznlczgC0FUZNoJds7T3RaF PNAG/HsMvML38MGtJ4sr/uaF+tk4J0PHQQhby1MWbIRdSt7KH2YcYwNL9x8yE3UA == X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedugedrheeggdduvdegucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucenucfjughrpefuvffhfffkgggtgfesthekredttd dtlfenucfhrhhomhepoehgrhgvghhkhheslhhinhhugihfohhunhgurghtihhonhdrohhr gheqnecukfhppeekfedrkeeirdekledruddtjeenucevlhhushhtvghrufhiiigvpedune curfgrrhgrmhepmhgrihhlfhhrohhmpehgrhgvgheskhhrohgrhhdrtghomh X-ME-Proxy: Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) by mail.messagingengine.com (Postfix) with ESMTPA id 4F42C3280064; Fri, 7 Feb 2020 03:46:44 -0500 (EST) Subject: FAILED: patch "[PATCH] padata: Remove broken queue flushing" failed to apply to 4.4-stable tree To: herbert@gondor.apana.org.au, daniel.m.jordan@oracle.com, stable@vger.kernel.org Cc: From: Date: Fri, 07 Feb 2020 09:46:33 +0100 Message-ID: <15810651932494@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 07928d9bfc81640bab36f5190e8725894d93b659 Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Tue, 19 Nov 2019 13:17:31 +0800 Subject: [PATCH] padata: Remove broken queue flushing 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 diff --git a/kernel/padata.c b/kernel/padata.c index c3fec1413295..da56a235a255 100644 --- a/kernel/padata.c +++ b/kernel/padata.c @@ -35,6 +35,8 @@ #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; @@ -283,6 +285,7 @@ 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); @@ -292,6 +295,8 @@ 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; @@ -301,9 +306,12 @@ 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); } /** @@ -440,7 +448,7 @@ static struct parallel_data *padata_alloc_pd(struct padata_instance *pinst, padata_init_squeues(pd); atomic_set(&pd->seq_nr, -1); atomic_set(&pd->reorder_objects, 0); - atomic_set(&pd->refcnt, 0); + atomic_set(&pd->refcnt, 1); spin_lock_init(&pd->lock); pd->cpu = cpumask_first(pd->cpumask.pcpu); INIT_WORK(&pd->reorder_work, invoke_padata_reorder); @@ -466,29 +474,6 @@ 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); - } - - 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; @@ -502,10 +487,6 @@ 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. */ @@ -526,8 +507,8 @@ 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,