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=-10.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 7003FC433DF for ; Wed, 5 Aug 2020 19:22:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2570A206D4 for ; Wed, 5 Aug 2020 19:22:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596655340; bh=Xh72F486odY76FUAK2jXhgVJtEsGnpXK2OaBFEF9p80=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=n1cyUZXXzBHAdkhl/aUTr90+yG+4wPw6EOIvCKyZqcqw3iu+m6h5FPZVhvMarcDOp yu8NEsihBuNdAMecu6ereJUlGIf8JqFmlgrIcpF+m3JTLnn29yq253Ccu7t7cX7CIE 93sPW1BQEeIywCc+9zaiNdhyMAg+O2guxZ/3nc94= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728371AbgHETWE (ORCPT ); Wed, 5 Aug 2020 15:22:04 -0400 Received: from mail.kernel.org ([198.145.29.99]:43124 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728975AbgHERl7 (ORCPT ); Wed, 5 Aug 2020 13:41:59 -0400 Received: from localhost (unknown [213.57.247.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 44D3423330; Wed, 5 Aug 2020 14:55:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596639331; bh=Xh72F486odY76FUAK2jXhgVJtEsGnpXK2OaBFEF9p80=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=u1Iv44Shaxv8Aru3MEjHnMPn8CDTLDu+wrfhSzC2DzurOxUCTBxyKjE80y25mZpCs Jdd9tAzfvX6VGlWlKtx2DZUEikva+ha8idKqetB2keaQScFqFZQeunVW667D6+KlLK DMXKgKlm/EfFM8UXoGdzCxne5/TM37y5qPLs8tvM= Date: Wed, 5 Aug 2020 17:55:28 +0300 From: Leon Romanovsky To: Haris Iqbal Cc: Danil Kipnis , Jinpu Wang , linux-rdma@vger.kernel.org, linux-block@vger.kernel.org, dledford@redhat.com, Jason Gunthorpe , kernel test robot Subject: Re: [PATCH v2] RDMA/rtrs-srv: Incorporate ib_register_client into rtrs server init Message-ID: <20200805145528.GK4432@unreal> References: <20200623172321.GC6578@ziepe.ca> <20200804133759.377950-1-haris.iqbal@cloud.ionos.com> <20200805055712.GE4432@unreal> <20200805090435.GF4432@unreal> <20200805131239.GI4432@unreal> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Wed, Aug 05, 2020 at 07:23:58PM +0530, Haris Iqbal wrote: > On Wed, Aug 5, 2020 at 6:42 PM Leon Romanovsky wrote: > > > > On Wed, Aug 05, 2020 at 04:39:16PM +0530, Haris Iqbal wrote: > > > On Wed, Aug 5, 2020 at 2:34 PM Leon Romanovsky wrote: > > > > > > > > On Wed, Aug 05, 2020 at 01:20:09PM +0530, Haris Iqbal wrote: > > > > > On Wed, Aug 5, 2020 at 11:27 AM Leon Romanovsky wrote: > > > > > > > > > > > > On Tue, Aug 04, 2020 at 07:07:58PM +0530, Md Haris Iqbal wrote: > > > > > > > The rnbd_server module's communication manager (cm) initialization depends > > > > > > > on the registration of the "network namespace subsystem" of the RDMA CM > > > > > > > agent module. As such, when the kernel is configured to load the > > > > > > > rnbd_server and the RDMA cma module during initialization; and if the > > > > > > > rnbd_server module is initialized before RDMA cma module, a null ptr > > > > > > > dereference occurs during the RDMA bind operation. > > > > > > > > > > > > > > Call trace below, > > > > > > > > > > > > > > [ 1.904782] Call Trace: > > > > > > > [ 1.904782] ? xas_load+0xd/0x80 > > > > > > > [ 1.904782] xa_load+0x47/0x80 > > > > > > > [ 1.904782] cma_ps_find+0x44/0x70 > > > > > > > [ 1.904782] rdma_bind_addr+0x782/0x8b0 > > > > > > > [ 1.904782] ? get_random_bytes+0x35/0x40 > > > > > > > [ 1.904782] rtrs_srv_cm_init+0x50/0x80 > > > > > > > [ 1.904782] rtrs_srv_open+0x102/0x180 > > > > > > > [ 1.904782] ? rnbd_client_init+0x6e/0x6e > > > > > > > [ 1.904782] rnbd_srv_init_module+0x34/0x84 > > > > > > > [ 1.904782] ? rnbd_client_init+0x6e/0x6e > > > > > > > [ 1.904782] do_one_initcall+0x4a/0x200 > > > > > > > [ 1.904782] kernel_init_freeable+0x1f1/0x26e > > > > > > > [ 1.904782] ? rest_init+0xb0/0xb0 > > > > > > > [ 1.904782] kernel_init+0xe/0x100 > > > > > > > [ 1.904782] ret_from_fork+0x22/0x30 > > > > > > > [ 1.904782] Modules linked in: > > > > > > > [ 1.904782] CR2: 0000000000000015 > > > > > > > [ 1.904782] ---[ end trace c42df88d6c7b0a48 ]--- > > > > > > > > > > > > > > All this happens cause the cm init is in the call chain of the module init, > > > > > > > which is not a preferred practice. > > > > > > > > > > > > > > So remove the call to rdma_create_id() from the module init call chain. > > > > > > > Instead register rtrs-srv as an ib client, which makes sure that the > > > > > > > rdma_create_id() is called only when an ib device is added. > > > > > > > > > > > > > > Fixes: 9cb837480424 ("RDMA/rtrs: server: main functionality") > > > > > > > Reported-by: kernel test robot > > > > > > > Signed-off-by: Md Haris Iqbal > > > > > > > --- > > > > > > > drivers/infiniband/ulp/rtrs/rtrs-srv.c | 77 +++++++++++++++++++++++++- > > > > > > > drivers/infiniband/ulp/rtrs/rtrs-srv.h | 7 +++ > > > > > > > 2 files changed, 81 insertions(+), 3 deletions(-) > > > > > > > > > > > > Please don't send vX patches as reply-to in "git send-email" command. > > > > > > > > > > > > > > > > > > > > diff --git a/drivers/infiniband/ulp/rtrs/rtrs-srv.c b/drivers/infiniband/ulp/rtrs/rtrs-srv.c > > > > > > > index 0d9241f5d9e6..916f99464d09 100644 > > > > > > > --- a/drivers/infiniband/ulp/rtrs/rtrs-srv.c > > > > > > > +++ b/drivers/infiniband/ulp/rtrs/rtrs-srv.c > > > > > > > @@ -16,6 +16,7 @@ > > > > > > > #include "rtrs-srv.h" > > > > > > > #include "rtrs-log.h" > > > > > > > #include > > > > > > > +#include > > > > > > > > > > > > > > MODULE_DESCRIPTION("RDMA Transport Server"); > > > > > > > MODULE_LICENSE("GPL"); > > > > > > > @@ -31,6 +32,7 @@ MODULE_LICENSE("GPL"); > > > > > > > static struct rtrs_rdma_dev_pd dev_pd; > > > > > > > static mempool_t *chunk_pool; > > > > > > > struct class *rtrs_dev_class; > > > > > > > +static struct rtrs_srv_ib_ctx ib_ctx; > > > > > > > > > > > > > > static int __read_mostly max_chunk_size = DEFAULT_MAX_CHUNK_SIZE; > > > > > > > static int __read_mostly sess_queue_depth = DEFAULT_SESS_QUEUE_DEPTH; > > > > > > > @@ -2033,6 +2035,62 @@ static void free_srv_ctx(struct rtrs_srv_ctx *ctx) > > > > > > > kfree(ctx); > > > > > > > } > > > > > > > > > > > > > > +static int rtrs_srv_add_one(struct ib_device *device) > > > > > > > +{ > > > > > > > + struct rtrs_srv_ctx *ctx; > > > > > > > + int ret; > > > > > > > + > > > > > > > + /* > > > > > > > + * Keep a track on the number of ib devices added > > > > > > > + */ > > > > > > > + ib_ctx.ib_dev_count++; > > > > > > > + > > > > > > > + if (!ib_ctx.rdma_init) { > > > > > > > + /* > > > > > > > + * Since our CM IDs are NOT bound to any ib device we will create them > > > > > > > + * only once > > > > > > > + */ > > > > > > > + ctx = ib_ctx.srv_ctx; > > > > > > > + ret = rtrs_srv_rdma_init(ctx, ib_ctx.port); > > > > > > > + if (ret) { > > > > > > > + /* > > > > > > > + * We errored out here. > > > > > > > + * According to the ib code, if we encounter an error here then the > > > > > > > + * error code is ignored, and no more calls to our ops are made. > > > > > > > + */ > > > > > > > + pr_err("Failed to initialize RDMA connection"); > > > > > > > + return ret; > > > > > > > + } > > > > > > > + ib_ctx.rdma_init = true; > > > > > > > > > > > > This rdma_init == false is equal to ib_ctx.ib_dev_count == 0 and the > > > > > > logic can be simplified. > > > > > > > > > > Yes, this was the first logic in my head. But I have few thoughts, > > > > > The below suggestions uses "ib_ctx.ib_dev_count" as a marker for > > > > > successful execution of rtrs_srv_rdma_init() and not really an IB > > > > > device count. Meaning if we have multiple calls to add, due to > > > > > multiple devices, our count would stay 1. And while removal we might > > > > > end up calling rdma_destroy_id() on our first remove call even though > > > > > another device is still remaining. > > > > > > > > > > If we increment "ib_ctx.ib_dev_count" every time add is called, even > > > > > before we call rtrs_srv_rdma_init() and irrespective of whether > > > > > rtrs_srv_rdma_init() succeeds or not, then we are keeping a count of > > > > > IB devices added. However, when remove is called, we now know the > > > > > number of devices added, but not whether rtrs_srv_rdma_init() was > > > > > successful or not. We may end up calling rdma_destroy_id() on NULL > > > > > cm_ids > > > > > > > > > > Does this make sense or am I missing something? > > > > > > > > > > > > > > > > > > > > > > if (ib_ctx.ib_dev_count) > > > > > > return 0; > > > > > > My understanding is, with the above 2 lines, after one add in which > > > rtrs_srv_rdma_init() succeeds, we won't even go below this, and hence > > > subsequent increments will not happen. > > > > Is it better? > > > > if (ib_ctx.ib_dev_count) > > goto out; > > > > .... > > > > out: > > ib_ctx.ib_dev_count++; > > return 0; > > > > You don't need to take the code proposed in the ML as is. > > Yes, hence I posted a theoretical scenario which discussed 2 possible scenarios. > > case 1, single variable tracking only number of devices added. > when remove is called, we now know the > number of devices added, but not whether rtrs_srv_rdma_init() was > successful or not. We may end up calling rdma_destroy_id() on NULL > cm_ids If rtrs_srv_rdma_init() fails to initialize on first attempt, why do you want to continue to load rtrs? > > case 2, single variable tracking success of rtrs_srv_rdma_init() > If we have multiple IB devices added, while removal we won't know when > to call rdma_destroy_id(), Your code doesn't know it either, it calls to destroy on last ib_dev. > > > > > > > > > > > > > > > > > > ctx = ib_ctx.srv_ctx; > > > > > > ret = rtrs_srv_rdma_init(ctx, ib_ctx.port); > > > > > > if (ret) > > > > > > return ret; > > > > > > Also here, when rtrs_srv_rdma_init() fails, we return without > > > incrementing. IMHO, in this logic, we are not using > > > "ib_ctx.ib_dev_count" to track the number of devices, but to mark > > > successful execution of rtrs_srv_rdma_init() > > > > Of course, you should increment in success only. > > I am confused again. What exactly are you suggesting we track with > "ib_ctx.ib_dev_count"? > According to my understanding, we can't possibly track both "number of > devices added" and "success of rtrs_srv_rdma_init()". Why don't you ask your colleagues? They will guide you. Thanks