> The uverbs layer DOES handle the counting/listing (see, for example, > list_add_tail at the end of ib_uverbs_create_xrc_rcv_qp.
But that is the per-process list of rcv QPs... not the reference counting for each rcv QP. Look at how trivial ib_uverbs_destroy_xrc_rcv_qp is -- there is no reference counting of the real object there. > However, I had an additional problem -- to distribute async events received > for the xrc_rcv QP to all registered processes (so that each could unregister > and allow the QP to be destroyed -- the ref count going to zero). > In my original implementation, the low-level driver was responsible for > generating > the events for all the processes. To move this mechanism to the core would > require > a fairly extensive re-write. I would need to introduce ib_core methods for > create, > reg, unreg, and destroy, since the uverbs layer operates per user process > and does > not track across multiple processes. I was concerned that modifications of > this > magnitude would introduce instability in XRC, and would require a > significant QA cycle It seems to me that it should, if anything, be easier to track all these lists at the uverbs layer. We already have a global xrcd structure for each xrcd that we could easily stick a list of rcv QPs in (and keep the list of rcv QP registrations per rcv QP). I do see your point that the changes might be fairly large (although the total XRC code is not so big), but we shouldn't stick ourselves with a wrong implementation just because that implementation was already tested. > Finally, I do not believe that it is such a bad thing to have low-level > driver > procedures for reg/unreg here. If a given low-level driver has > implementation > details that it wishes to record, it should have the opportunity to do so. Hmm. I'm having a hard time imagining what those details are -- I really do feel that this tracking of per-process reference counting etc is something that we should do once in the core, rather than hiding it in low-level drivers. - R. -- Roland Dreier <rola...@cisco.com> || For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/index.html -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
