From patchwork Tue Jan 31 18:09:15 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bjorn Helgaas X-Patchwork-Id: 9547975 X-Patchwork-Delegate: geert@linux-m68k.org Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 892FC60425 for ; Tue, 31 Jan 2017 18:12:17 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7BE30209CD for ; Tue, 31 Jan 2017 18:12:17 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 7068C27DF9; Tue, 31 Jan 2017 18:12:17 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D9708209CD for ; Tue, 31 Jan 2017 18:12:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751515AbdAaSKJ (ORCPT ); Tue, 31 Jan 2017 13:10:09 -0500 Received: from mail.kernel.org ([198.145.29.136]:51866 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751525AbdAaSJU (ORCPT ); Tue, 31 Jan 2017 13:09:20 -0500 Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 1188E2020F; Tue, 31 Jan 2017 18:09:18 +0000 (UTC) Received: from localhost (unknown [69.55.156.165]) (using TLSv1.2 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E408C20204; Tue, 31 Jan 2017 18:09:16 +0000 (UTC) Date: Tue, 31 Jan 2017 12:09:15 -0600 From: Bjorn Helgaas To: Geert Uytterhoeven Cc: Bjorn Helgaas , Simon Horman , Linux-Renesas , linux-pci Subject: Re: [PATCH] PCI: rcar: Check for OF device match early Message-ID: <20170131180915.GA16450@bhelgaas-glaptop.roam.corp.google.com> References: <20170131151044.14062.85997.stgit@bhelgaas-glaptop.roam.corp.google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-Virus-Scanned: ClamAV using ClamSMTP Sender: linux-renesas-soc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-renesas-soc@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP On Tue, Jan 31, 2017 at 04:33:15PM +0100, Geert Uytterhoeven wrote: > Hi Bjorn, > > On Tue, Jan 31, 2017 at 4:10 PM, Bjorn Helgaas wrote: > > A match in the rcar_pcie_of_match[] table is required, so check that first, > > before we start setting up things that need to be undone if it fails. No > > functional change intended. > > > > Signed-off-by: Bjorn Helgaas > > --- > > drivers/pci/host/pcie-rcar.c | 10 +++++----- > > 1 file changed, 5 insertions(+), 5 deletions(-) > > > > diff --git a/drivers/pci/host/pcie-rcar.c b/drivers/pci/host/pcie-rcar.c > > index 0d9b96c3c49d..c91ff0b91be8 100644 > > --- a/drivers/pci/host/pcie-rcar.c > > +++ b/drivers/pci/host/pcie-rcar.c > > @@ -1129,6 +1129,10 @@ static int rcar_pcie_probe(struct platform_device *pdev) > > int err; > > int (*hw_init_fn)(struct rcar_pcie *); > > > > + of_id = of_match_device(rcar_pcie_of_match, dev); > > + if (!of_id || !of_id->data) > > + return -EINVAL; > > + > > As this driver is DT-only, none of the above can fail, and you could just do > > hw_init_fn = of_device_get_match_data(dev); > > instead, getting rid of of_id completely. Oh, I really like that, thanks for pointing that out! I was about to say that I personally would not check of_id->data for NULL, because it is only NULL if somebody adds an entry to rcar_pcie_of_match without a .data member. In that case, I'd rather take the NULL pointer dereference than return -EINVAL because it's too easy to ignore the -EINVAL. What do you think about the following? commit 25bd3aa972ee32f04590aa68b2b785dce36b036a Author: Bjorn Helgaas Date: Tue Jan 31 08:45:49 2017 -0600 PCI: rcar: Use of_device_get_match_data() to simplify probe This is a DT-only driver, so the only way to call rcar_pcie_probe() is to match an entry in rcar_pcie_of_match[], so of_id cannot be NULL. Furthermore, of_id->data can only be NULL if an rcar_pcie_of_match[] entry has a NULL .data member. That's a driver defect, and we don't want to return -EINVAL, which is easy to ignore. We'd rather take the NULL pointer dereference so we notice the problem and fix it. Use of_device_get_match_data() to retrieve the hw_init_fn pointer. No functional change intended. Suggested-by: Geert Uytterhoeven Signed-off-by: Bjorn Helgaas Reviewed-by: Geert Uytterhoeven Acked-by: Simon Horman diff --git a/drivers/pci/host/pcie-rcar.c b/drivers/pci/host/pcie-rcar.c index 0d9b96c3c49d..cb07c45c1858 100644 --- a/drivers/pci/host/pcie-rcar.c +++ b/drivers/pci/host/pcie-rcar.c @@ -1125,7 +1125,6 @@ static int rcar_pcie_probe(struct platform_device *pdev) struct device *dev = &pdev->dev; struct rcar_pcie *pcie; unsigned int data; - const struct of_device_id *of_id; int err; int (*hw_init_fn)(struct rcar_pcie *); @@ -1149,11 +1148,6 @@ static int rcar_pcie_probe(struct platform_device *pdev) if (err) return err; - of_id = of_match_device(rcar_pcie_of_match, dev); - if (!of_id || !of_id->data) - return -EINVAL; - hw_init_fn = of_id->data; - pm_runtime_enable(dev); err = pm_runtime_get_sync(dev); if (err < 0) { @@ -1162,6 +1156,7 @@ static int rcar_pcie_probe(struct platform_device *pdev) } /* Failure to get a link might just be that no cards are inserted */ + hw_init_fn = of_device_get_match_data(dev); err = hw_init_fn(pcie); if (err) { dev_info(dev, "PCIe link down\n");