[ofa-general] Re: potential device removal deadlock

[Steve Wise]

Sean Hefty wrote:
>> I'm looking at the rdma_[u]cm modules and how they generate
>> DEVICE_REMOVAL events to user applications, and I see a potential
>> deadlock.  ib_unregister_device() calls the ib_client remove() functions
>> in the reverse order from which the ib_clients were registered.  And if
>> you look at ib_uverbs_remove_one(), you'll see it will block until all
>> references from user apps are released.  So if ib_uverbs remove() gets
>> called _before_ the rdma_cm remove() function, then the unregister
>> process will deadlock since applications don't get notification of the
>> device removal.
>>     
>
> You want the remove device functions called in the reverse order of
> registration.
>
>   

Not quite. You want rdma_cm to be notified of the device removal 
_before_ ib_uverbs...