> >>>>>>>>>> Moving the QP into error state right after with rdma_disconnect > >>>>>>>>>> you are not sure that none of the subset of the invalidations > >>>>>>>>>> that _were_ posted completed and you get the corresponding MRs > >>>>>>>>>> in a bogus state... > >>>>>>>>> > >>>>>>>>> Moving the QP to error state and then draining the CQs means > >>>>>>>>> that all LOCAL_INV WRs that managed to get posted will get > >>>>>>>>> completed or flushed. That's already handled today. > >>>>>>>>> > >>>>>>>>> It's the WRs that didn't get posted that I'm worried about > >>>>>>>>> in this patch. > >>>>>>>>> > >>>>>>>>> Are there RDMA consumers in the kernel that use that third > >>>>>>>>> argument to recover when LOCAL_INV WRs cannot be posted? > >>>>>>>> > >>>>>>>> None :) > >>>>>>>> > >>>>>>>>>>> I suppose I could reset these MRs instead (that is, > >>>>>>>>>>> pass them to ib_dereg_mr). > >>>>>>>>>> > >>>>>>>>>> Or, just wait for a completion for those that were posted > >>>>>>>>>> and then all the MRs are in a consistent state. > >>>>>>>>> > >>>>>>>>> When a LOCAL_INV completes with IB_WC_SUCCESS, the associated > >>>>>>>>> MR is in a known state (ie, invalid). > >>>>>>>>> > >>>>>>>>> The WRs that flush mean the associated MRs are not in a known > >>>>>>>>> state. Sometimes the MR state is different than the hardware > >>>>>>>>> state, for example. Trying to do anything with one of these > >>>>>>>>> inconsistent MRs results in IB_WC_BIND_MW_ERR until the thing > >>>>>>>>> is deregistered. > >>>>>>>> > >>>>>>>> Correct. > >>>>>>>> > >>>>>>> > >>>>>>> It is legal to invalidate an MR that is not in the valid state. So you > >>>>> don't > >>>>>>> have to deregister it, you can assume it is valid and post another LINV > >>> WR. > >>>>>> > >>>>>> I've tried that. Once the MR is inconsistent, even LOCAL_INV > >>>>>> does not work. > >>>>>> > >>>>> > >>>>> Maybe IB Verbs don't mandate that invalidating an invalid MR must be > >>> allowed? > >>>>> (looking at the verbs spec now). > >>>> > >>> > >>> IB Verbs doesn't have specify this requirement. iW verbs does. So > > transport > >>> independent applications cannot rely on it. So ib_dereg_mr() seems to be > > the > >>> only thing you can do. > >>> > >>>> If the MR is truly invalid, then there is no issue, and > >>>> the second LOCAL_INV completes successfully. > >>>> > >>>> The problem is after a flushed LOCAL_INV, the MR state > >>>> sometimes does not match the hardware state. The MR is > >>>> neither registered or invalid. > >>>> > >>> > >>> There is a difference, at least with iWARP devices, between the MR state: > > VALID > >>> vs INVALID, and if the MR is allocated or not. > >>> > >>>> A flushed LOCAL_INV tells you nothing more than that the > >>>> LOCAL_INV didn't complete. The MR state at that point is > >>>> unknown. > >>>> > >>> > >>> With respect to iWARP and cxgb4: when you allocate a fastreg MR, HW has an > >> entry > >>> for that MR and it is marked "allocated". The MR record in HW also has a > > state: > >>> VALID or INVALID. While the MR is "allocated" you can post WRs to > > invalidate it > >>> which changes the state to INVALID, or fast-register memory which makes it > >>> VALID. Regardless of what happens on any given QP, the MR remains > > "allocated" > >>> until you call ib_dereg_mr(). So at least for cxgb4, you could in fact just > >>> post another LINV to get it back to a known state that allows subsequent > >>> fast-reg WRs. > >>> > >>> Perhaps IB devices don't work this way. > >>> > >>> What error did you get when you tried just doing an LINV after a flush? > >> > >> With CX-2 and CX-3, after a flushed LOCAL_INV, trying either > >> a FASTREG or LOCAL_INV on that MR can sometimes complete with > >> IB_WC_MW_BIND_ERR. > > > > > > I wonder if you post a FASREG+LINV+LINV if you'd get the same failure? IE > > invalidate the same rkey twice. Just as an experiment... > > Once the MR is in this state, FASTREG does not work either. > All FASTREG and LINV flush with IB_WC_MW_BIND_ERR until > the MR is deregistered. Mellanox can probably tell us why. I was just wondering if posting a double LINV on a valid working FRMR would fail with these devices. But its moot. As you've concluded, looks like the only safe was to handle this is to dereg them and reallocate... -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
