Re: Bad behavior by rdma-core ?

Bob Pearson
2021-10-14T16:43:43Z

On 10/14/21 11:14 AM, Bob Pearson wrote:
> On 10/14/21 9:57 AM, Bob Pearson wrote:
>> I have been chasing a bug in the rxe driver seen in the python tests (test_cq_events_ud).
>> The following occurs
>>
>> The first time I execute this test it creates two AHs which are allocated by
>> rdma-core and passed to rxe_create_ah. The test attempts to destroy them
>> (i.e. rxe_destroy_ah is called in the provider driver) but rdma-core does not
>> destroy them (i.e. rxe_destroy_ah is not called in the kernel).
>>
>> The rxe driver saves the AV state and some metadata for these AHs and keeps it
>> since it thinks they are still active.
>>
>> The second or third time I execute this test two new AHs are created by
>> rxe_create_ah but the memory passed in from rdma-core is the same as the first
>> test. I.e. it has recycled them but they are still active in the driver so
>> the result is chaos.
>>
>> Somehow rdma-core thinks it has destroyed the AHs but it does not call down to the
>> driver. This only occurs for AHs AFAIK.
>>
>> Bob
>>
>
> The cause seems simple enough.
>
> In uverbs_cmd.c ib_uverbs_create_ah() calls rdma_create_user_ah() which
> eventually calls device->ops.create_user_ah() or device->ops.create_ah().
>
> But ib_uverbs_destroy_ah does *not* call rdma_uverbs_destroy_ah() it just
should be rdma_destroy_user_ah()
> deletes the object.
>