From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jiri Pirko Subject: Re: [Patch net-next v2 3/4] net_sched: remove tc class reference counting Date: Fri, 25 Aug 2017 11:41:16 +0200 Message-ID: <20170825094116.GE2023@nanopsycho> References: <20170824235130.28503-1-xiyou.wangcong@gmail.com> <20170824235130.28503-4-xiyou.wangcong@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org, jhs@mojatatu.com To: Cong Wang Return-path: Received: from mail-wr0-f196.google.com ([209.85.128.196]:38844 "EHLO mail-wr0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754938AbdHYJlT (ORCPT ); Fri, 25 Aug 2017 05:41:19 -0400 Received: by mail-wr0-f196.google.com with SMTP id o76so760188wrb.5 for ; Fri, 25 Aug 2017 02:41:18 -0700 (PDT) Content-Disposition: inline In-Reply-To: <20170824235130.28503-4-xiyou.wangcong@gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: Fri, Aug 25, 2017 at 01:51:29AM CEST, xiyou.wangcong@gmail.com wrote: >For TC classes, their ->get() and ->put() are always paired, and the >reference counting is completely useless, because: > >1) For class modification and dumping paths, we already hold RTNL lock, > so all of these ->get(),->change(),->put() are atomic. > >2) For filter bindiing/unbinding, we use other reference counter than > this one, and they should have RTNL lock too. > >3) For ->qlen_notify(), it is special because it is called on ->enqueue() > path, but we already hold qdisc tree lock there, and we hold this > tree lock when graft or delete the class too, so it should not be gone > or changed until we release the tree lock. > >Therefore, this patch removes ->get() and ->put(), but: > >1) Adds a new ->find() to find the pointer to a class by classid, no > refcnt. > >2) Move the original class destroy upon the last refcnt into ->delete(), > right after releasing tree lock. This is fine because the class is > already removed from hash when holding the lock. > >For those who also use ->put() as ->unbind(), just rename them to reflect >this change. > >Cc: Jamal Hadi Salim >Signed-off-by: Cong Wang Look very nice. Thanks! Acked-by: Jiri Pirko