[ofw] RE: convert_av_handle

[Sean Hefty]

list copied on reply:

>I have a question for you.  I am dying with access violation in ibald.dll due
>to this dereference of dgrm.ud.h_av.
>
>
>
>if( h_qp->type == IB_QPT_UNRELIABLE_DGRM )
>
>{
>
>p_qp_ioctl->in.send_wr[num_wr].dgrm.ud.h_av =
>
>            (ib_av_handle_t) (ULONG_PTR) p_wr->dgrm.ud.h_av->obj.hdl;
>
>}
>
>
>
>It turns out that dgrm.ud.h_av was "converted " in this code:
>
>      /* Convert all AV handles for verb provider usage. */
>
>      for( p_wr = p_send_wr; p_wr; p_wr = p_wr->p_next )
>
>      {
>
>            CL_ASSERT( p_wr->dgrm.ud.h_av );
>
>            p_wr->dgrm.ud.rsvd = p_wr->dgrm.ud.h_av;
>
>            p_wr->dgrm.ud.h_av = convert_av_handle( h_qp, p_wr->dgrm.ud.h_av );
>
>      }
>
>
>
>      status = h_qp->pfn_ud_post_send(
>
>            h_qp->h_ud_send_qp, p_send_wr, pp_send_failure );
>
>
>
>And, the conversion does this:
>
>#define convert_av_handle(h_qp, h_av) \
>
>                ((h_qp)->h_ci_qp?(h_av)-
>>h_ci_av:(ib_av_handle_t)(ULONG_PTR)(h_av)->obj.hdl)
>
>
>
>I suppose that means that obj.hdl in h_av is not initialized correctly.
>
>I don't understand what this av conversion is and I'm trying to figure out what
>this means in terms of missing driver functionality.  So, any help most
>appreciated.

IBAL and verbs providers maintain separate structures.  When crossing from the
IBAL interface to the verbs provider interface, all handles must be converted.
This is easily seen when for objects like QPs or CQs.  E.g. IBAL takes a pointer
to its QP structure, then calls the verbs provider with its handle.
ib_query_qp(h_qp ...) becomes ci_query_qp(h_qp->h_ci_qp ...)

The use of address vectors is similar.  Only in this case, since the IBAL
address vector handle is inside the work request, rather than creating an
entirely new work request list with the correct verbs provider handle, IBAL
simply munges the handle in the original list before giving the WR list to the
verbs provider.

This is the reason that winverbs uses an address vector 'key' in work requests,
rather than a handle that must be replaced.

- Sean