[openib-general] [PATCH 1/2] ib/core/uverbs: return sq_draining value in query_qp response

[Roland Dreier]

    Jack> Why is this any worse than having a situation where a kernel
    Jack> module has a bug in which it returns an incorrect value in
    Jack> an ABI field in which no name change is involved?

    Jack> If we fix such a bug, do we need to increment the ABI as well?

Obviously fixing the kernel so it doesn't return a wrong value is OK.
And I don't see any way to fix old libibverbs, which is just returning
garbage to the consumer in the sq_draining field.

However, you snipped the second part of my reply:

    Roland> Fortunately ib_uverbs_query_qp_resp has some reserved
    Roland> slots we can use for sq_draining.  However, this means
    Roland> that an old kernel will always return 0 for sq_draining.
    Roland> However I'm not sure if we could do better...

So I don't think we need to bump the ABI.  Let's just take one of the
reserved fields that we're lucky to have in the query QP response, and
put sq_draining in there.

 - R.