Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751948AbdC0Fog (ORCPT ); Mon, 27 Mar 2017 01:44:36 -0400 Received: from fllnx209.ext.ti.com ([198.47.19.16]:55799 "EHLO fllnx209.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751852AbdC0Fo1 (ORCPT ); Mon, 27 Mar 2017 01:44:27 -0400 Subject: Re: [PATCH] PCI: dwc: fix crash seen due to missing ops To: Niklas Cassel , Joao Pinto , , References: <20170321144354.15452-1-niklass@axis.com> <744bf393-4fd8-5e64-423f-f9a033d61106@axis.com> CC: , , From: Kishon Vijay Abraham I Message-ID: <0aec14f1-619a-e6a2-2e1c-1230e373a551@ti.com> Date: Mon, 27 Mar 2017 11:13:20 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 MIME-Version: 1.0 In-Reply-To: <744bf393-4fd8-5e64-423f-f9a033d61106@axis.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4087 Lines: 110 Hi, On Thursday 23 March 2017 01:10 PM, Niklas Cassel wrote: > On 03/22/2017 04:47 PM, Joao Pinto wrote: >> Hi Niklas, >> >> ?s 2:43 PM de 3/21/2017, Niklas Cassel escreveu: >>> From: Niklas Cassel >>> >>> Fix the following crash, seen in dwc/pcie-artpec6. >>> >>> Unable to handle kernel NULL pointer dereference at virtual address 00000004 >>> pgd = c0204000 >>> [00000004] *pgd=00000000 >>> Internal error: Oops: 5 [#1] SMP ARM >>> Modules linked in: >>> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.11.0-rc3-next-20170321 #1 >>> Hardware name: Axis ARTPEC-6 Platform >>> task: db098000 task.stack: db096000 >>> PC is at dw_pcie_writel_dbi+0x2c/0xd0 >>> ... >>> >>> While at it, fix the same problem for pcie-designware-plat. >>> >>> Fixes: 442ec4c04d12 ("PCI: dwc: all: Split struct pcie_port into host-only and core structures") >>> Signed-off-by: Niklas Cassel >>> --- >>> drivers/pci/dwc/pcie-artpec6.c | 4 ++++ >>> drivers/pci/dwc/pcie-designware-plat.c | 4 ++++ >>> 2 files changed, 8 insertions(+) >>> >>> diff --git a/drivers/pci/dwc/pcie-artpec6.c b/drivers/pci/dwc/pcie-artpec6.c >>> index fcd3ef845883..6d23683c0892 100644 >>> --- a/drivers/pci/dwc/pcie-artpec6.c >>> +++ b/drivers/pci/dwc/pcie-artpec6.c >>> @@ -234,6 +234,9 @@ static int artpec6_add_pcie_port(struct artpec6_pcie *artpec6_pcie, >>> return 0; >>> } >>> >>> +static const struct dw_pcie_ops dw_pcie_ops = { >>> +}; >>> + >>> static int artpec6_pcie_probe(struct platform_device *pdev) >>> { >>> struct device *dev = &pdev->dev; >>> @@ -252,6 +255,7 @@ static int artpec6_pcie_probe(struct platform_device *pdev) >>> return -ENOMEM; >>> >>> pci->dev = dev; >>> + pci->ops = &dw_pcie_ops; >>> >>> artpec6_pcie->pci = pci; >>> >>> diff --git a/drivers/pci/dwc/pcie-designware-plat.c b/drivers/pci/dwc/pcie-designware-plat.c >>> index b6c832ba39dd..f20d494922ab 100644 >>> --- a/drivers/pci/dwc/pcie-designware-plat.c >>> +++ b/drivers/pci/dwc/pcie-designware-plat.c >>> @@ -86,6 +86,9 @@ static int dw_plat_add_pcie_port(struct pcie_port *pp, >>> return 0; >>> } >>> >>> +static const struct dw_pcie_ops dw_pcie_ops = { >>> +}; >>> + >>> static int dw_plat_pcie_probe(struct platform_device *pdev) >>> { >>> struct device *dev = &pdev->dev; >>> @@ -103,6 +106,7 @@ static int dw_plat_pcie_probe(struct platform_device *pdev) >>> return -ENOMEM; >>> >>> pci->dev = dev; >>> + pci->ops = &dw_pcie_ops; >>> >>> dw_plat_pcie->pci = pci; >>> >>> >> In the case of pcie-designware-plat you have the declaration of pci->ops: >> https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git/tree/drivers/pci/dwc/pcie-designware-plat.c#n78 >> >> and in artpec6 in here: >> https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git/tree/drivers/pci/dwc/pcie-artpec6.c#n226 >> >> Both declarations are made previously of calling dw_pcie_host_init(), so why do >> you need this dummy ops in the probe function? I never had that necessity. > > Hello Joao > > Since commit 442ec4c04d12, we now have two different ops, > dw_pcie_ops (ops for dw_pcie) and dw_pcie_host_ops (ops for a pcie_port), > note that they are different. The dw_pcie_ops is missing for pcie-artpec6 > and pcie-designware-plat (since we are using the generic link-up function). > > Before commit 442ec4c04d12, dw_pcie_writel_dbi had dw_pcie_host_ops as > parameter, after the commit it has dw_pcie_ops as parameter. > It should crash on pcie-designware-plat as well, since there are other > functions, like dw_pcie_link_up, that assumes that pci->ops != null. > > Another alternative to adding the dummy ops would be to add null checks > for all uses off pci->ops in pcie-designware.c. > I don't like the idea to sprinkle null checks everywhere pci->ops is used. I'm okay either ways. Acked-by: Kishon Vijay Abraham I > > One could add a null check in dw_pcie_host_init, but without a dummy ops > we would still fail this check, so our drivers would still be non-functional > in Linus's tree. >