From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753173AbbF2C0x (ORCPT ); Sun, 28 Jun 2015 22:26:53 -0400 Received: from mga03.intel.com ([134.134.136.65]:44988 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752950AbbF2C0p convert rfc822-to-8bit (ORCPT ); Sun, 28 Jun 2015 22:26:45 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.13,696,1427785200"; d="scan'208";a="752198370" From: "Jiang, Dave" To: Jiang Liu CC: "Williams, Dan J" , "Koul, Vinod" , Jarkko Nikula , "David Woodhouse" , "Luck, Tony" , "x86@kernel.org" , "linux-kernel@vger.kernel.org" , "dmaengine@vger.kernel.org" Subject: Re: [RFC Patch V1] ioatdma: Ignore IOAT devices under hotplug-capable PCI host bridge Thread-Topic: [RFC Patch V1] ioatdma: Ignore IOAT devices under hotplug-capable PCI host bridge Thread-Index: AQHQnP4m1YypbcHp5kOCOZmVensfd53DXe+A//+OIjk= Date: Mon, 29 Jun 2015 02:26:38 +0000 Message-ID: <5F215805-02D7-4E23-8FDC-33522BD6247B@intel.com> References: <1433226969-8748-1-git-send-email-jiang.liu@linux.intel.com>,<5590A9F3.6070408@linux.intel.com> In-Reply-To: <5590A9F3.6070408@linux.intel.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Jun 28, 2015, at 7:14 PM, Jiang Liu wrote: > > Hi Dave, > Gentle Ping:) Any suggestion about this patch? > Thanks! > Gerry I'm fine with it if Dan has no objections. >> On 2015/6/2 14:36, Jiang Liu wrote: >> The dmaengine core assumes that async DMA devices will only be removed >> when they not used anymore, or it assumes dma_async_device_unregister() >> will only be called by dma driver exit routines. But this assumption is >> not true for the IOAT driver, which calls dma_async_device_unregister() >> from ioat_remove(). So current IOAT driver doesn't support device >> hot-removal because it may cause system crash to hot-remove an inuse >> IOAT device. >> >> To support CPU socket hot-removal, all PCI devices, including IOAT >> devices embedded in the socket, will be hot-removed. The idea solution >> is to enhance the dmaengine core and IOAT driver to support hot-removal, >> but that's too hard. >> >> This patch implements a hack to disable IOAT devices under hotplug-capable >> CPU socket so it won't break socket hot-removal. >> >> Signed-off-by: Jiang Liu >> --- >> drivers/dma/ioat/pci.c | 34 ++++++++++++++++++++++++++++++++++ >> 1 file changed, 34 insertions(+) >> >> diff --git a/drivers/dma/ioat/pci.c b/drivers/dma/ioat/pci.c >> index 76f0dc688a19..3b8c9b03f4b3 100644 >> --- a/drivers/dma/ioat/pci.c >> +++ b/drivers/dma/ioat/pci.c >> @@ -27,6 +27,7 @@ >> #include >> #include >> #include >> +#include >> #include "dma.h" >> #include "dma_v2.h" >> #include "registers.h" >> @@ -148,6 +149,34 @@ alloc_ioatdma(struct pci_dev *pdev, void __iomem *iobase) >> return d; >> } >> >> +/* >> + * The dmaengine core assumes that async DMA devices will only be removed >> + * when they not used anymore, or it assumes dma_async_device_unregister() >> + * will only be called by dma driver exit routines. But this assumption is >> + * not true for the IOAT driver, which calls dma_async_device_unregister() >> + * from ioat_remove(). So current IOAT driver doesn't support device >> + * hot-removal because it may cause system crash to hot-remove inuse IOAT >> + * devices. >> + * >> + * This is a hack to disable IOAT devices under ejectable PCI host bridge >> + * so it won't break PCI host bridge hot-removal. >> + */ >> +static bool ioat_pci_has_ejectable_acpi_ancestor(struct pci_dev *pdev) >> +{ >> +#ifdef CONFIG_ACPI >> + struct pci_bus *bus = pdev->bus; >> + struct acpi_device *adev; >> + >> + while (bus->parent) >> + bus = bus->parent; >> + for (adev = ACPI_COMPANION(bus->bridge); adev; adev = adev->parent) >> + if (adev->flags.ejectable) >> + return true; >> +#endif >> + >> + return false; >> +} >> + >> static int ioat_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id) >> { >> void __iomem * const *iomap; >> @@ -155,6 +184,11 @@ static int ioat_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id) >> struct ioatdma_device *device; >> int err; >> >> + if (ioat_pci_has_ejectable_acpi_ancestor(pdev)) { >> + dev_dbg(&pdev->dev, "ignore ejectable IOAT device.\n"); >> + return -ENODEV; >> + } >> + >> err = pcim_enable_device(pdev); >> if (err) >> return err; >>