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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 27F53C43334 for ; Wed, 20 Jul 2022 11:00:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232114AbiGTLAe (ORCPT ); Wed, 20 Jul 2022 07:00:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44126 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231916AbiGTLAc (ORCPT ); Wed, 20 Jul 2022 07:00:32 -0400 Received: from mail-ed1-x52e.google.com (mail-ed1-x52e.google.com [IPv6:2a00:1450:4864:20::52e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5C58023BFF for ; Wed, 20 Jul 2022 04:00:30 -0700 (PDT) Received: by mail-ed1-x52e.google.com with SMTP id y4so23263380edc.4 for ; Wed, 20 Jul 2022 04:00:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=resnulli-us.20210112.gappssmtp.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=C4+HHnUIuB2/v0S+7mvaPyVjpmyHFc/HVYrgbDdX/ck=; b=xzdceVJuHTXh9s5fbz29KbEHKtIvl/0dZgD2GZY7UeIHA2LVoOD8DKJj5B6aoMqTWm JSejXaYonUpOlUESeSDFodEOQI56lWcZ7afAMgdKf9f/cx8nM4Cot4k64yxg/p3enQ9o DcGMR77GPOfvPl+XfJlfwgepy43AO4zqea6mk/rTZgjlAr+MFeCmAdGL0HUkbrSocXev KP9IZ+vENnoC/qiEUT60ZGFBHQhjiM347vU/EW75k+SdKnzd27fhw+BkO9ii0edR2GRq QWdVB4oBPDyoJ0tqGBJ2xDowzQYp7gXjvpDqTXrahi+TDleh1SfqDLUcLKw3xr3N1KDM u+Ag== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=C4+HHnUIuB2/v0S+7mvaPyVjpmyHFc/HVYrgbDdX/ck=; b=pRva7rhnZPKOlGagqqaTOvTTSgNtjHClmISkRcrCMDUZ40R6BmMuoWxfug7v0WAee0 MGbPM/C9mllae31o9W6u1U3kcGGEOjakNcyX8GS3zyuNJ0oHriOvddLWfwY0j+nFB6TZ 2IFVMDHSx9nluCmWLDYZyuc9qY9lZpYabicsZ0vleM7XK7j9Hr1gPQH5si5y4zZ8ekJ0 CzsBmFioqQpZbiNBl9aeIuJkQHA0EXFD31c3TeMNHhxodURnbkHWcrgYABiwB3kMd1UK 9vTY1KvEfjXRxwCJnm9Wr5hsF6qYvTNEAdrAefUDqjOQFVo5mVNu8ldTJqTxXgyyDyVD GSLQ== X-Gm-Message-State: AJIora+9/xKTkasdVg1jvwe5uIrOEpMx50M74ffwUumwaw/wYZstvsPc kXR1YGDbSBQ8G58Yk83ebHUfAsqta/2rxfXo5RE= X-Google-Smtp-Source: AGRyM1u+6mYq2PWgMsdUM4ZJtYa805Yi+PyS4tk0i01EQv3aAN1xSsEryMXZKp3cL26rA3Sy2aWZmA== X-Received: by 2002:a50:fa91:0:b0:43a:4f13:4767 with SMTP id w17-20020a50fa91000000b0043a4f134767mr51052843edr.10.1658314828839; Wed, 20 Jul 2022 04:00:28 -0700 (PDT) Received: from localhost ([85.163.43.78]) by smtp.gmail.com with ESMTPSA id 8-20020a170906328800b0072f5fa175b2sm1323654ejw.8.2022.07.20.04.00.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 20 Jul 2022 04:00:28 -0700 (PDT) Date: Wed, 20 Jul 2022 13:00:27 +0200 From: Jiri Pirko To: Ido Schimmel Cc: netdev@vger.kernel.org, davem@davemloft.net, kuba@kernel.org, petrm@nvidia.com, pabeni@redhat.com, edumazet@google.com, mlxsw@nvidia.com, saeedm@nvidia.com, snelson@pensando.io Subject: Re: [patch net-next v2 01/12] net: devlink: make sure that devlink_try_get() works with valid pointer during xarray iteration Message-ID: References: <20220719064847.3688226-1-jiri@resnulli.us> <20220719064847.3688226-2-jiri@resnulli.us> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Wed, Jul 20, 2022 at 09:45:26AM CEST, idosch@nvidia.com wrote: >On Tue, Jul 19, 2022 at 08:48:36AM +0200, Jiri Pirko wrote: >> From: Jiri Pirko >> >> Remove dependency on devlink_mutex during devlinks xarray iteration. > >Missing motivation... Need to explain that devlink_mutex is held >throughout every user space command and that while issuing a reload and >registering / unregistering auxiliary devlink instances we will >deadlock on this mutex. Fixed. > >> >> The devlinks xarray consistency is ensured by internally by xarray. > >s/by// Fixed. > >> There is a reference taken when working with devlink using >> devlink_try_get(). But there is no guarantee that devlink pointer >> picked during xarray iteration is not freed before devlink_try_get() >> is called. >> >> Make sure that devlink_try_get() works with valid pointer. >> Achieve it by: >> 1) Splitting devlink_put() so the completion is sent only >> after grace period. Completion unblocks the devlink_unregister() >> routine, which is followed-up by devlink_free() >> 2) Iterate the devlink xarray holding RCU read lock. >> >> Signed-off-by: Jiri Pirko