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author | Jiang Liu <jiang.liu@linux.intel.com> | 2015-07-08 15:41:42 +0800 |
---|---|---|
committer | Vinod Koul <vinod.koul@intel.com> | 2015-07-16 18:28:28 +0530 |
commit | b6c52c634506d52b3a2dc18503980d717e478739 (patch) | |
tree | 751c0c1fd2b536507355bc4ed5f85c5e005e8e21 /drivers/dma/ioat | |
parent | 7618d0359c167d89d7e904a00487be4945c10a65 (diff) | |
download | linux-stable-b6c52c634506d52b3a2dc18503980d717e478739.tar.gz linux-stable-b6c52c634506d52b3a2dc18503980d717e478739.tar.bz2 linux-stable-b6c52c634506d52b3a2dc18503980d717e478739.zip |
dmaengine: ioatdma: Ignore IOAT devices under hotplug-capable PCI host bridge
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 <jiang.liu@linux.intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Diffstat (limited to 'drivers/dma/ioat')
-rw-r--r-- | drivers/dma/ioat/pci.c | 34 |
1 files changed, 34 insertions, 0 deletions
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; |