Return-Path: linux-nfs-owner@vger.kernel.org Received: from smtp.opengridcomputing.com ([72.48.136.20]:45256 "EHLO smtp.opengridcomputing.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756807AbaGBT4S convert rfc822-to-8bit (ORCPT ); Wed, 2 Jul 2014 15:56:18 -0400 From: "Steve Wise" To: "'Devesh Sharma'" , "'Chuck Lever'" , , References: <20140623223201.1634.83888.stgit@manet.1015granger.net> <20140623223942.1634.89063.stgit@manet.1015granger.net> <53B45D7B.4020705@opengridcomputing.com> <006001cf962e$e20df020$a629d060$@opengridcomputing.com> In-Reply-To: Subject: RE: [PATCH v1 05/13] xprtrdma: Don't drain CQs on transport disconnect Date: Wed, 2 Jul 2014 14:56:54 -0500 Message-ID: <006401cf962f$c5ec49e0$51c4dda0$@opengridcomputing.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Sender: linux-nfs-owner@vger.kernel.org List-ID: > -----Original Message----- > From: Devesh Sharma [mailto:Devesh.Sharma@Emulex.Com] > Sent: Wednesday, July 02, 2014 2:54 PM > To: Steve Wise; 'Chuck Lever'; linux-rdma@vger.kernel.org; linux-nfs@vger.kernel.org > Subject: RE: [PATCH v1 05/13] xprtrdma: Don't drain CQs on transport disconnect > > > > > -----Original Message----- > > From: Steve Wise [mailto:swise@opengridcomputing.com] > > Sent: Thursday, July 03, 2014 1:21 AM > > To: Devesh Sharma; 'Chuck Lever'; linux-rdma@vger.kernel.org; linux- > > nfs@vger.kernel.org > > Subject: RE: [PATCH v1 05/13] xprtrdma: Don't drain CQs on transport > > disconnect > > > > > > > > > -----Original Message----- > > > From: Devesh Sharma [mailto:Devesh.Sharma@Emulex.Com] > > > Sent: Wednesday, July 02, 2014 2:43 PM > > > To: Steve Wise; Chuck Lever; linux-rdma@vger.kernel.org; > > > linux-nfs@vger.kernel.org > > > Subject: RE: [PATCH v1 05/13] xprtrdma: Don't drain CQs on transport > > > disconnect > > > > > > > -----Original Message----- > > > > From: Steve Wise [mailto:swise@opengridcomputing.com] > > > > Sent: Thursday, July 03, 2014 12:59 AM > > > > To: Devesh Sharma; Chuck Lever; linux-rdma@vger.kernel.org; linux- > > > > nfs@vger.kernel.org > > > > Subject: Re: [PATCH v1 05/13] xprtrdma: Don't drain CQs on transport > > > > disconnect > > > > > > > > On 7/2/2014 2:06 PM, Devesh Sharma wrote: > > > > > This change is very much prone to generate poll_cq errors because > > > > > of un-cleaned completions which still point to the non-existent > > > > > QPs. On the new connection when these completions are polled, the > > > > > poll_cq will fail > > > > because old QP pointer is already NULL. > > > > > Did anyone hit this situation during their testing? > > > > > > > > Hey Devesh, > > > > > > > > iw_cxgb4 will silently toss CQEs if the QP is not active. > > > > > > Ya, just now checked that in mlx and cxgb4 driver code. On the other > > > hand ocrdma is asserting a BUG-ON for such CQEs causing system panic. > > > Out of curiosity I am asking, how this change is useful here, is it > > > reducing the re-connection time...Anyhow rpcrdma_clean_cq was > > > discarding the completions (flush/successful both) > > > > > > > Well, I don't think there is anything restricting an application from destroying > > the QP with pending CQEs on its CQs. So it definitely shouldn't cause a > > BUG_ON() I think. I'll have to read up in the Verbs specs if destroying a QP > > kills all the pending CQEs... > > Oh confusion...let me clarify: in ocrdma BUG ON is hit in poll_cq() after re-connection happens > and cq is polled again. > Now the first completion in CQ still points to old QP-ID for which ocrdma does not have valid > QP pointer. > Right. Which means it’s a stale CQE. I don't think that should cause a BUG_ON. > > > > > > > > > > > > > > > > >> -----Original Message----- > > > > >> From: linux-rdma-owner@vger.kernel.org [mailto:linux-rdma- > > > > >> owner@vger.kernel.org] On Behalf Of Chuck Lever > > > > >> Sent: Tuesday, June 24, 2014 4:10 AM > > > > >> To: linux-rdma@vger.kernel.org; linux-nfs@vger.kernel.org > > > > >> Subject: [PATCH v1 05/13] xprtrdma: Don't drain CQs on transport > > > > >> disconnect > > > > >> > > > > >> CQs are not destroyed until unmount. By draining CQs on transport > > > > >> disconnect, successful completions that can change the > > > > >> r.frmr.state field can be missed. > > > > > > Still those are missed isn’t it....Since those successful completions > > > will still be dropped after re- connection. Am I missing something to > > > understanding the motivation... > > > > > > > >> > > > > >> Signed-off-by: Chuck Lever > > > > >> --- > > > > >> net/sunrpc/xprtrdma/verbs.c | 5 ----- > > > > >> 1 file changed, 5 deletions(-) > > > > >> > > > > >> diff --git a/net/sunrpc/xprtrdma/verbs.c > > > > >> b/net/sunrpc/xprtrdma/verbs.c index 3c7f904..451e100 100644 > > > > >> --- a/net/sunrpc/xprtrdma/verbs.c > > > > >> +++ b/net/sunrpc/xprtrdma/verbs.c > > > > >> @@ -873,9 +873,6 @@ retry: > > > > >> dprintk("RPC: %s: > > rpcrdma_ep_disconnect" > > > > >> " status %i\n", __func__, rc); > > > > >> > > > > >> - rpcrdma_clean_cq(ep->rep_attr.recv_cq); > > > > >> - rpcrdma_clean_cq(ep->rep_attr.send_cq); > > > > >> - > > > > >> xprt = container_of(ia, struct rpcrdma_xprt, rx_ia); > > > > >> id = rpcrdma_create_id(xprt, ia, > > > > >> (struct sockaddr *)&xprt- > > >rx_data.addr); > > > > @@ -985,8 +982,6 @@ > > > > >> rpcrdma_ep_disconnect(struct rpcrdma_ep *ep, struct rpcrdma_ia > > > > >> *ia) { > > > > >> int rc; > > > > >> > > > > >> - rpcrdma_clean_cq(ep->rep_attr.recv_cq); > > > > >> - rpcrdma_clean_cq(ep->rep_attr.send_cq); > > > > >> rc = rdma_disconnect(ia->ri_id); > > > > >> if (!rc) { > > > > >> /* returns without wait if not connected */ > > > > >> > > > > >> -- > > > > >> To unsubscribe from this list: send the line "unsubscribe linux-rdma" > > > > >> in the body of a message to majordomo@vger.kernel.org More > > > > majordomo > > > > >> info at http://vger.kernel.org/majordomo-info.html > > > > > N r y b X ǧv ^ )޺{.n + { " ^n r z  h &  G h  > > > > > ( 階 ݢj"  m z ޖ f h ~ mml== > >