From: Tom Tucker Subject: FW: [PATCH for 2.6.25] SVCRDMA: Use only 1 RDMA read scatter entry for iWARP adapters Date: Sun, 23 Mar 2008 22:06:08 -0500 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Cc: Roland Dreier , To: "J. Bruce Fields" Return-path: Received: from mail.es335.com ([67.65.19.105]:27124 "EHLO mail.es335.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750820AbYCXDGV (ORCPT ); Sun, 23 Mar 2008 23:06:21 -0400 In-Reply-To: Sender: linux-nfs-owner@vger.kernel.org List-ID: Bruce: If possible, this should go in 2.6.25. This was a merge error on my part. Thanks to Roland for figuring this out... Tom ------ Forwarded Message From: Tom Tucker Date: Sun, 23 Mar 2008 18:52:49 -0500 To: Roland Dreier , "J. Bruce Fields" Cc: NeilBrown , Trond Myklebust , , Conversation: [PATCH for 2.6.25] SVCRDMA: Use only 1 RDMA read scatter entry for iWARP adapters Subject: Re: [PATCH for 2.6.25] SVCRDMA: Use only 1 RDMA read scatter entry for iWARP adapters Ack. It's actually an _ancient_ remnant when it had to compile against iWARP vs. non-iWARP enabled OFA trees. On 3/23/08 4:27 PM, "Roland Dreier" wrote: > The iWARP protocol limits RDMA read requests to a single scatter > entry. NFS/RDMA has code in rdma_read_max_sge() that is supposed to > limit the sge_count for RDMA read requests to 1, but the code to do > that is inside an #ifdef RDMA_TRANSPORT_IWARP block. In the mainline > kernel at least, RDMA_TRANSPORT_IWARP is an enum and not a > preprocessor #define, so the #ifdef'ed code is never compiled. > > In my test of a kernel build with -j8 on an NFS/RDMA mount, this > problem eventually leads to trouble starting with: > > svcrdma: Error posting send = -22 > svcrdma : RDMA_READ error = -22 > > and things go downhill from there. > > The trivial fix is to delete the #ifdef guard. The check seems to be > a remnant of when the NFS/RDMA code was not merged and needed to > compile against multiple kernel versions, although I don't think it > ever worked as intended. In any case now that the code is upstream > there's no need to test whether the RDMA_TRANSPORT_IWARP constant is > defined or not. > > Without this patch, my kernel build on an NFS/RDMA mount using NetEffect > adapters quickly and 100% reproducibly failed with an error like: > > ld: final link failed: Software caused connection abort > > With the patch applied I was able to complete a kernel build on the > same setup. > > Signed-off-by: Roland Dreier > --- > I guess this should probably go into 2.6.25 if possible, since things > get seriously screwed up in my testing once this bug is hit. > > Not sure why this doesn't trigger on Chelsio or Ammasso adapters (or > does it?), but it's easily reproducible here on Neteffect adapters > (and that driver is now upstream for 2.6.25). > > diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c > b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c > index ab54a73..9712716 100644 > --- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c > +++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c > @@ -237,14 +237,12 @@ static void rdma_set_ctxt_sge(struct svc_rdma_op_ctxt > *ctxt, > > static int rdma_read_max_sge(struct svcxprt_rdma *xprt, int sge_count) > { > -#ifdef RDMA_TRANSPORT_IWARP > if ((RDMA_TRANSPORT_IWARP == > rdma_node_get_transport(xprt->sc_cm_id-> > device->node_type)) > && sge_count > 1) > return 1; > else > -#endif > return min_t(int, sge_count, xprt->sc_max_sge); > } > > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html ------ End of Forwarded Message