From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7BE19C3B1A1 for ; Fri, 14 Feb 2020 17:25:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5ECC5222C2 for ; Fri, 14 Feb 2020 17:25:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391317AbgBNRY7 (ORCPT ); Fri, 14 Feb 2020 12:24:59 -0500 Received: from mga17.intel.com ([192.55.52.151]:43172 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390928AbgBNRY7 (ORCPT ); Fri, 14 Feb 2020 12:24:59 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga107.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 14 Feb 2020 09:24:56 -0800 X-IronPort-AV: E=Sophos;i="5.70,441,1574150400"; d="scan'208";a="223081205" Received: from ddalessa-mobl.amr.corp.intel.com (HELO [10.254.204.146]) ([10.254.204.146]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-SHA; 14 Feb 2020 09:24:54 -0800 Subject: Re: [PATCH 1/3] infiniband: hw: hfi1: verbs.c: Use built-in RCU list checking To: Madhuparna Bhowmik , Jason Gunthorpe Cc: mike.marciniszyn@intel.com, "Paul E. McKenney" , Joel Fernandes , Amol Grover , linux-kernel-mentees@lists.linuxfoundation.org, rcu@vger.kernel.org, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org References: <20200114162345.19995-1-madhuparnabhowmik04@gmail.com> <20200114165740.GB22037@ziepe.ca> <74adec84-ec5b-ea1b-7adf-3f8608838259@intel.com> <25133367-6544-d0af-ae30-5178909748b1@intel.com> From: Dennis Dalessandro Message-ID: Date: Fri, 14 Feb 2020 12:24:52 -0500 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.4.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On 2/14/2020 10:43 AM, Madhuparna Bhowmik wrote: > > > On Wed, Jan 15, 2020 at 12:05 AM > wrote: > > From: Dennis Dalessandro > > > On 1/14/2020 12:00 PM, Dennis Dalessandro wrote: > > On 1/14/2020 11:57 AM, Jason Gunthorpe wrote: > >> On Tue, Jan 14, 2020 at 09:53:45PM +0530, > >> madhuparnabhowmik04@gmail.com > wrote: > >>> From: Madhuparna Bhowmik > > >>> > >>> list_for_each_entry_rcu has built-in RCU and lock checking. > >>> Pass cond argument to list_for_each_entry_rcu. > >>> > >>> Signed-off-by: Madhuparna Bhowmik > > > >>>   drivers/infiniband/hw/hfi1/verbs.c | 2 +- > >>>   1 file changed, 1 insertion(+), 1 deletion(-) > >>> > >>> diff --git a/drivers/infiniband/hw/hfi1/verbs.c > >>> b/drivers/infiniband/hw/hfi1/verbs.c > >>> index 089e201d7550..22f2d4fd2577 100644 > >>> +++ b/drivers/infiniband/hw/hfi1/verbs.c > >>> @@ -515,7 +515,7 @@ static inline void hfi1_handle_packet(struct > >>> hfi1_packet *packet, > >>>                          opa_get_lid(packet->dlid, 9B)); > >>>           if (!mcast) > >>>               goto drop; > >>> -        list_for_each_entry_rcu(p, &mcast->qp_list, list) { > >>> +        list_for_each_entry_rcu(p, &mcast->qp_list, list, > >>> lockdep_is_held(&(ibp->rvp.lock))) { > >> > >> Okay, this looks reasonable > >> > >> Mike, Dennis, is this the right lock to test? > >> > > > > I'm looking at that right now actually, I don't think this is > correct. > > Wanted to talk to Mike before I send a response though. > > > > -Denny > > That's definitely going to throw a ton of lock dep messages. It's not > really the right lock either. Instead what we probably need to do is > what we do in the non-multicast part of the code and take the > rcu_read_lock(). > > I'd say hold off on this and we'll fix it right. Same goes for the > qib one. > > Alright, thank you for reviewing. > > The rdmavt one though looks to be OK. I'll give it a test. > > Hi, > I just wanted to follow up on this. > Any updates? > Also, is the bug fixed now? > > Thank you, > Madhuparna > > Thank you, > Madhuparna > > -Denny > I've got a patch going through internal discussion and testing for adding rcu read locking. The RDMAVT patch, I was OK with going in, I guess I just mentioned that in a reply rather than adding an RB tag. Let me go ahead and do that. -Denny