> >>>>>>>> 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... -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
