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    SubjectRe: [PATCH 3/4] pci aer: fix deadlock in do_recovery
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    On 9/27/2017 5:42 PM, Govindarajulu Varadarajan wrote:
    > CPU0 CPU1
    > ---------------------------------------------------------------------
    > __driver_attach()
    > device_lock(&dev->mutex) <--- device mutex lock here
    > driver_probe_device()
    > pci_enable_sriov()
    > pci_iov_add_virtfn()
    > pci_device_add()
    > aer_isr() <--- pci aer error
    > do_recovery()
    > broadcast_error_message()
    > pci_walk_bus()
    > down_read(&pci_bus_sem) <--- rd sem

    How about releasing the device_lock here on CPU0? or in other words keep
    device_lock as short as possible?

    > down_write(&pci_bus_sem) <-- stuck on wr sem
    > report_error_detected()
    > device_lock(&dev->mutex)<--- DEAD LOCK


    --
    Sinan Kaya
    Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
    Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.

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