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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 6C0DCC43460 for ; Fri, 9 Apr 2021 09:03:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3439460238 for ; Fri, 9 Apr 2021 09:03:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231749AbhDIJDf (ORCPT ); Fri, 9 Apr 2021 05:03:35 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:36540 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231127AbhDIJDa (ORCPT ); Fri, 9 Apr 2021 05:03:30 -0400 Received: from 1.general.cking.uk.vpn ([10.172.193.212]) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1lUn2p-0002Js-BC; Fri, 09 Apr 2021 09:03:15 +0000 Subject: Re: [PATCH][next] mlxsw: spectrum_router: remove redundant initialization of variable force To: Ido Schimmel Cc: Jiri Pirko , Ido Schimmel , "David S . Miller" , Jakub Kicinski , netdev@vger.kernel.org, kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org, petrm@nvidia.com References: <20210327223334.24655-1-colin.king@canonical.com> From: Colin Ian King Message-ID: Date: Fri, 9 Apr 2021 10:03:14 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 29/03/2021 08:13, Ido Schimmel wrote: > On Sat, Mar 27, 2021 at 10:33:34PM +0000, Colin King wrote: >> From: Colin Ian King >> >> The variable force is being initialized with a value that is >> never read and it is being updated later with a new value. The >> initialization is redundant and can be removed. >> >> Addresses-Coverity: ("Unused value") >> Signed-off-by: Colin Ian King >> --- >> drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c >> index 6ccaa194733b..ff240e3c29f7 100644 >> --- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c >> +++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c >> @@ -5059,7 +5059,7 @@ mlxsw_sp_nexthop_obj_bucket_adj_update(struct mlxsw_sp *mlxsw_sp, >> { >> u16 bucket_index = info->nh_res_bucket->bucket_index; >> struct netlink_ext_ack *extack = info->extack; >> - bool force = info->nh_res_bucket->force; >> + bool force; > > Actually, there is a bug to be fixed here: > > ``` > diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c > index 6ccaa194733b..41259c0004d1 100644 > --- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c > +++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c > @@ -5068,8 +5068,9 @@ mlxsw_sp_nexthop_obj_bucket_adj_update(struct mlxsw_sp *mlxsw_sp, > /* No point in trying an atomic replacement if the idle timer interval > * is smaller than the interval in which we query and clear activity. > */ > - force = info->nh_res_bucket->idle_timer_ms < > - MLXSW_SP_NH_GRP_ACTIVITY_UPDATE_INTERVAL; > + if (!force && info->nh_res_bucket->idle_timer_ms < > + MLXSW_SP_NH_GRP_ACTIVITY_UPDATE_INTERVAL) > + force = true; > > adj_index = nh->nhgi->adj_index + bucket_index; > err = mlxsw_sp_nexthop_update(mlxsw_sp, adj_index, nh, force, ratr_pl); > ``` > > We should only fallback to a non-atomic replacement when the current > replacement is atomic and the idle timer is too short. > > We currently ignore the value of 'force'. This means that a non-atomic > replacement ('force' is true) can be made atomic if idle timer is larger > than 1 second. > > Colin, do you mind if I submit it formally as a fix later this week? I > want to run it through our usual process. Will mention you in > Reported-by, obviously. Sure. Good idea. > >> char ratr_pl_new[MLXSW_REG_RATR_LEN]; >> char ratr_pl[MLXSW_REG_RATR_LEN]; >> u32 adj_index; >> -- >> 2.30.2 >>