On Tue, Jun 02, 2015 at 02:37:31PM +0800, Jiang Liu wrote: > Ccing Rafael, it's ACPI hotplug related. > > 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. > > So below looks okay though I wonder how hard would it be to fix hot unplug ?
-- ~Vinod > > Signed-off-by: Jiang Liu <[email protected]> > > --- > > 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 <linux/interrupt.h> > > #include <linux/dca.h> > > #include <linux/slab.h> > > +#include <linux/acpi.h> > > #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; > > -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
