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=-6.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no 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 5647CC4338F for ; Mon, 16 Aug 2021 15:55:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3D76D60FD7 for ; Mon, 16 Aug 2021 15:55:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236907AbhHPP4R (ORCPT ); Mon, 16 Aug 2021 11:56:17 -0400 Received: from mail.kernel.org ([198.145.29.99]:42472 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237406AbhHPPyt (ORCPT ); Mon, 16 Aug 2021 11:54:49 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 79E3660F4B; Mon, 16 Aug 2021 15:53:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1629129229; bh=wjnnlmVi3Qh8uS9MigPn3yJA2hsAEy/ZbPM5padIYCI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=eR/LqbLzu0HGG6fZDVjcWPHFekOC2mneksHBNVGKeuM9Cw1T1xzV9bbzjuBxgM4tj nYvJPXZZQ7o3v51+n3svA0qXNaulJG9xK00Q9XOEiYlTG6tRQKQcCrFMNXBKGnpab/ FVQEHFabQBsmdr2te0sSHcg4MKwJ0svoTihZcgbOWoZA0DoaqCp+qUvWK8NzWKU2zN 1vLyDRANb7AVO36P2kMmtWK+iwp0WVo2XI7i7wttx7zL4GceB0nSmlyPitZoG4DCg3 4V5dR45G+J3nF8bJCw9mdVky+JYZt7LuWfIwKcvV5+F+LA9kFiWI08tQuG+ltBuuza 1UYeUDAgk/pfw== Date: Mon, 16 Aug 2021 18:53:45 +0300 From: Leon Romanovsky To: Jakub Kicinski Cc: "David S . Miller" , Guangbin Huang , Jacob Keller , Jiri Pirko , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Salil Mehta , Shannon Nelson , Yisen Zhuang , Yufeng Mo Subject: Re: [PATCH net-next 3/6] devlink: Count struct devlink consumers Message-ID: References: <20210816084741.1dd1c415@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210816084741.1dd1c415@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 16, 2021 at 08:47:41AM -0700, Jakub Kicinski wrote: > On Sat, 14 Aug 2021 12:57:28 +0300 Leon Romanovsky wrote: > > From: Leon Romanovsky > > > > The struct devlink itself is protected by internal lock and doesn't > > need global lock during operation. That global lock is used to protect > > addition/removal new devlink instances from the global list in use by > > all devlink consumers in the system. > > > > The future conversion of linked list to be xarray will allow us to > > actually delete that lock, but first we need to count all struct devlink > > users. > > Not a problem with this set but to state the obvious the global devlink > lock also protects from concurrent execution of all the ops which don't > take the instance lock (DEVLINK_NL_FLAG_NO_LOCK). You most likely know > this but I thought I'd comment on an off chance it helps. The end goal will be something like that: 1. Delete devlink lock 2. Rely on xa_lock() while grabbing devlink instance (past devlink_try_get) 3. Convert devlink->lock to be read/write lock to make sure that we can run get query in parallel. 4. Open devlink netlink to parallel ops, ".parallel_ops = true". Thanks > > > The reference counting provides us a way to ensure that no new user > > space commands success to grab devlink instance which is going to be > > destroyed makes it is safe to access it without lock. >