[dpdk-dev] [Bug 361] device reset handling with igb_uio

[bugzilla@dpdk.org]

https://bugs.dpdk.org/show_bug.cgi?id=361

            Bug ID: 361
           Summary: device reset handling with igb_uio
           Product: DPDK
           Version: unspecified
          Hardware: All
                OS: All
            Status: UNCONFIRMED
          Severity: normal
          Priority: Normal
         Component: ethdev
          Assignee: dev@dpdk.org
          Reporter: santosh.rastapur@broadcom.com
  Target Milestone: ---

Created attachment 73
  --> https://bugs.dpdk.org/attachment.cgi?id=73&action=edit
msi-x vector allocation for igb_uio after device reset

Hi,

    I have a question on igb_uio.

From the below function call traces, vfio-pci module frees/allocates msi-x
vector table as part of
interrupt disable/enable. Where as igb-uio module, only masks/unmasks the
msi-x interrupt.
Does this mean, when using igb_uio, device can't undergo reset which clears
MSI-X vector table?
How to handle device reset with igb_uio?

igb-uio:
rte_intr_disable->uio_intr_disable->igbuio_pci_irqcontrol->pci_msi_mask_irq
rte_intr_enable->uio_intr_enable->igbuio_pci_irqcontrol->pci_msi_unmask_irq

igbuio_pci_open->igbuio_pci_enable_interrupts->pci_alloc_irq_vectors/request_irq
igbuio_pci_release->igbuio_pci_disable_interrupts->free_irq->pci_free_irq_vectors

vfio-pci:
rte_intr_disable->vfio_disable_msix->vfio_pci_ioctl->vfio_msi_disable->pci_free_irq_vectors
rte_intr_enable->vfio_enable_msix->vfio_pci_ioctl->vfio_msi_enable->pci_alloc_irq_vectors/vfio_msi_set_vector_signal->request_irq

I am using the attached hack to overcome this. What is the correct way to
handle this? 
This is a hack as I am assigning "udev->info.irq = -1" when interrupt is
disabled to prevent uio_write from exiting.

kernel/linux/igb_uio/igb_uio.c: igbuio_pci_irqcontrol
    igbuio_pci_disable_interrupts(udev);
    udev->info.irq = -1; <-- Assigning to -1 and not 0.

Basically uio_write will not call igbuio_pci_enable_interrupts to enable the
interrupts back if irq is 0.

drivers/uio/uio.c: uio_write
        if (!idev->info->irq) {
                retval = -EIO;
                goto out;
        }
        if (!idev->info->irqcontrol) {
                retval = -ENOSYS;
                goto out;
        }
        retval = idev->info->irqcontrol(idev->info, irq_on);


Regards
-Santosh

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