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,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 8C8BEC433DF for ; Tue, 26 May 2020 19:01:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 69776208B6 for ; Tue, 26 May 2020 19:01:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590519684; bh=XJJyoQtDvFZe4chBEWSdTN/XbaT92U3oizYWFpXeESA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=TMab4pRyHNf8lOmbX6qhzC8FAFw+Mn387i5LucfmKI2YiriBCyNLa1f5hTNbKwqiq FQIasZ6oBDEkfdpyKV2pBaulP2HJW3/gBkckOclcSYUY8qkMHKQIRyrUVVyQZNURmQ v6E5wxfR/pcI+5fzyJZfBaTRQwi6ghd3H2CNX4aw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389859AbgEZTBX (ORCPT ); Tue, 26 May 2020 15:01:23 -0400 Received: from mail.kernel.org ([198.145.29.99]:55404 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389833AbgEZTBJ (ORCPT ); Tue, 26 May 2020 15:01:09 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A3D9F20849; Tue, 26 May 2020 19:01:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590519669; bh=XJJyoQtDvFZe4chBEWSdTN/XbaT92U3oizYWFpXeESA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zgPFCbQ42cu0IBU5bkkTDxPL0+tGHUYiYNlO1ygS/zAQnF+CZ5tLQ8g4SL9AHX4xk VbnP7LbYCJW7QSBAzYhubOOCO/0qqAoZ+ckL0IMyNixyeAsFZic1LoXLkbuyvdXDwf ixzZeZPyuQa4zQnqxj5oK54ypG1gW6Pq2ZF7WUfg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mathias Krause , Herbert Xu , Ben Hutchings Subject: [PATCH 4.14 05/59] padata: ensure padata_do_serial() runs on the correct CPU Date: Tue, 26 May 2020 20:52:50 +0200 Message-Id: <20200526183908.707547348@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200526183907.123822792@linuxfoundation.org> References: <20200526183907.123822792@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Mathias Krause commit 350ef88e7e922354f82a931897ad4a4ce6c686ff upstream. If the algorithm we're parallelizing is asynchronous we might change CPUs between padata_do_parallel() and padata_do_serial(). However, we don't expect this to happen as we need to enqueue the padata object into the per-cpu reorder queue we took it from, i.e. the same-cpu's parallel queue. Ensure we're not switching CPUs for a given padata object by tracking the CPU within the padata object. If the serial callback gets called on the wrong CPU, defer invoking padata_reorder() via a kernel worker on the CPU we're expected to run on. Signed-off-by: Mathias Krause Signed-off-by: Herbert Xu Cc: Ben Hutchings Signed-off-by: Greg Kroah-Hartman --- include/linux/padata.h | 2 ++ kernel/padata.c | 20 +++++++++++++++++++- 2 files changed, 21 insertions(+), 1 deletion(-) --- a/include/linux/padata.h +++ b/include/linux/padata.h @@ -37,6 +37,7 @@ * @list: List entry, to attach to the padata lists. * @pd: Pointer to the internal control structure. * @cb_cpu: Callback cpu for serializatioon. + * @cpu: Cpu for parallelization. * @seq_nr: Sequence number of the parallelized data object. * @info: Used to pass information from the parallel to the serial function. * @parallel: Parallel execution function. @@ -46,6 +47,7 @@ struct padata_priv { struct list_head list; struct parallel_data *pd; int cb_cpu; + int cpu; int info; void (*parallel)(struct padata_priv *padata); void (*serial)(struct padata_priv *padata); --- a/kernel/padata.c +++ b/kernel/padata.c @@ -133,6 +133,7 @@ int padata_do_parallel(struct padata_ins padata->cb_cpu = cb_cpu; target_cpu = padata_cpu_hash(pd); + padata->cpu = target_cpu; queue = per_cpu_ptr(pd->pqueue, target_cpu); spin_lock(&queue->parallel.lock); @@ -376,10 +377,21 @@ void padata_do_serial(struct padata_priv int cpu; struct padata_parallel_queue *pqueue; struct parallel_data *pd; + int reorder_via_wq = 0; pd = padata->pd; cpu = get_cpu(); + + /* We need to run on the same CPU padata_do_parallel(.., padata, ..) + * was called on -- or, at least, enqueue the padata object into the + * correct per-cpu queue. + */ + if (cpu != padata->cpu) { + reorder_via_wq = 1; + cpu = padata->cpu; + } + pqueue = per_cpu_ptr(pd->pqueue, cpu); spin_lock(&pqueue->reorder.lock); @@ -396,7 +408,13 @@ void padata_do_serial(struct padata_priv put_cpu(); - padata_reorder(pd); + /* If we're running on the wrong CPU, call padata_reorder() via a + * kernel worker. + */ + if (reorder_via_wq) + queue_work_on(cpu, pd->pinst->wq, &pqueue->reorder_work); + else + padata_reorder(pd); } EXPORT_SYMBOL(padata_do_serial);