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=-16.2 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,URIBL_BLOCKED autolearn=unavailable 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 E0707C433E0 for ; Fri, 12 Mar 2021 20:40:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9C6A464F49 for ; Fri, 12 Mar 2021 20:40:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234976AbhCLUj4 (ORCPT ); Fri, 12 Mar 2021 15:39:56 -0500 Received: from mail.kernel.org ([198.145.29.99]:37322 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234936AbhCLUji (ORCPT ); Fri, 12 Mar 2021 15:39:38 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 7CA2864F4F; Fri, 12 Mar 2021 20:39:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1615581577; bh=9xbU4dGm9+BmmqkFklPfuZZosdug6fd3AsnEv7H5YFw=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=HwKo5k8pp1FCYm+q0FK8hZDzmOtZx9D48iVHE47cQK63UFdrBQCVKqUKLkgEBggln 9ztDXjeFMO5NtU6M81ttmz3YIzjAGdpaoj3WUyaTpYbLYPOIKTitTDDSUkBhPVh3ei uZsnO60vXuNiDQWVZ67GOIH2ex/69BES8gJ7TKBgxsWmrOjmXpp0jtb76zJB+drQ+5 ttjsPLmcKVIKwI3YB6xyobjyZP8xBLzeJdU5wwcKBBOdxC6tVTrjKJeom0pbVqECZk AfgwD4VNAjFL9YMwxOIBwj+mIvgXP13JwgZm35A3RHZfv+EulcxAypQ0uvjMBrvARD TGvtqBg9cRwfw== Date: Fri, 12 Mar 2021 14:39:36 -0600 From: Bjorn Helgaas To: Logan Gunthorpe Cc: linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, linux-pci@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org, Stephen Bates , Christoph Hellwig , Dan Williams , Jason Gunthorpe , Christian =?iso-8859-1?Q?K=F6nig?= , Ira Weiny , John Hubbard , Don Dutile , Matthew Wilcox , Daniel Vetter , Jakowski Andrzej , Minturn Dave B , Jason Ekstrand , Dave Hansen , Xiong Jianxin Subject: Re: [RFC PATCH v2 01/11] PCI/P2PDMA: Pass gfp_mask flags to upstream_bridge_distance_warn() Message-ID: <20210312203936.GA2286981@bjorn-Precision-5520> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210311233142.7900-2-logang@deltatee.com> Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Thu, Mar 11, 2021 at 04:31:31PM -0700, Logan Gunthorpe wrote: > In order to call this function from a dma_map function, it must not sleep. > The only reason it does sleep so to allocate the seqbuf to print > which devices are within the ACS path. s/this function/upstream_bridge_distance_warn()/ ? s/so to/is to/ Maybe the subject could say something about the purpose, e.g., allow calling from atomic context or something? "Pass gfp_mask flags" sort of restates what we can read from the patch, but without the motivation of why this is useful. > Switch the kmalloc call to use a passed in gfp_mask and don't print that > message if the buffer fails to be allocated. > > Signed-off-by: Logan Gunthorpe Acked-by: Bjorn Helgaas > --- > drivers/pci/p2pdma.c | 21 +++++++++++---------- > 1 file changed, 11 insertions(+), 10 deletions(-) > > diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c > index 196382630363..bd89437faf06 100644 > --- a/drivers/pci/p2pdma.c > +++ b/drivers/pci/p2pdma.c > @@ -267,7 +267,7 @@ static int pci_bridge_has_acs_redir(struct pci_dev *pdev) > > static void seq_buf_print_bus_devfn(struct seq_buf *buf, struct pci_dev *pdev) > { > - if (!buf) > + if (!buf || !buf->buffer) > return; > > seq_buf_printf(buf, "%s;", pci_name(pdev)); > @@ -495,25 +495,26 @@ upstream_bridge_distance(struct pci_dev *provider, struct pci_dev *client, > > static enum pci_p2pdma_map_type > upstream_bridge_distance_warn(struct pci_dev *provider, struct pci_dev *client, > - int *dist) > + int *dist, gfp_t gfp_mask) > { > struct seq_buf acs_list; > bool acs_redirects; > int ret; > > - seq_buf_init(&acs_list, kmalloc(PAGE_SIZE, GFP_KERNEL), PAGE_SIZE); > - if (!acs_list.buffer) > - return -ENOMEM; > + seq_buf_init(&acs_list, kmalloc(PAGE_SIZE, gfp_mask), PAGE_SIZE); > > ret = upstream_bridge_distance(provider, client, dist, &acs_redirects, > &acs_list); > if (acs_redirects) { > pci_warn(client, "ACS redirect is set between the client and provider (%s)\n", > pci_name(provider)); > - /* Drop final semicolon */ > - acs_list.buffer[acs_list.len-1] = 0; > - pci_warn(client, "to disable ACS redirect for this path, add the kernel parameter: pci=disable_acs_redir=%s\n", > - acs_list.buffer); > + > + if (acs_list.buffer) { > + /* Drop final semicolon */ > + acs_list.buffer[acs_list.len - 1] = 0; > + pci_warn(client, "to disable ACS redirect for this path, add the kernel parameter: pci=disable_acs_redir=%s\n", > + acs_list.buffer); > + } > } > > if (ret == PCI_P2PDMA_MAP_NOT_SUPPORTED) { > @@ -566,7 +567,7 @@ int pci_p2pdma_distance_many(struct pci_dev *provider, struct device **clients, > > if (verbose) > ret = upstream_bridge_distance_warn(provider, > - pci_client, &distance); > + pci_client, &distance, GFP_KERNEL); > else > ret = upstream_bridge_distance(provider, pci_client, > &distance, NULL, NULL); > -- > 2.20.1 >