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=-0.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 23266C04EB8 for ; Wed, 12 Dec 2018 06:50:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CF8C72084E for ; Wed, 12 Dec 2018 06:50:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CF8C72084E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=davemloft.net Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726605AbeLLGuC (ORCPT ); Wed, 12 Dec 2018 01:50:02 -0500 Received: from shards.monkeyblade.net ([23.128.96.9]:51226 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726242AbeLLGuC (ORCPT ); Wed, 12 Dec 2018 01:50:02 -0500 Received: from localhost (unknown [IPv6:2601:601:9f80:35cd::bf5]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id A039D1455330F; Tue, 11 Dec 2018 22:50:01 -0800 (PST) Date: Tue, 11 Dec 2018 22:50:00 -0800 (PST) Message-Id: <20181211.225000.726755542677275663.davem@davemloft.net> To: lucien.xin@gmail.com Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-sctp@vger.kernel.org, marcelo.leitner@gmail.com, nhorman@tuxdriver.com, dave.hansen@linux.intel.com, rientjes@google.com, eparis@redhat.com, khorenko@virtuozzo.com Subject: Re: [PATCHv2 net 0/3] net: add support for flex_array_resize in flex_array From: David Miller In-Reply-To: References: X-Mailer: Mew version 6.8 on Emacs 26.1 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Tue, 11 Dec 2018 22:50:02 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Xin Long Date: Fri, 7 Dec 2018 14:30:32 +0800 > Without the support for the total_nr_elements's growing or shrinking > dynamically, flex_array is not that 'flexible'. Like when users want > to change the size, they have to redo flex_array_alloc and copy all > the elements from the old to the new one. The worse thing is every > element's memory gets changed. > > To implement flex_array_resize based on current code, the difficult > thing is to process the size border of FLEX_ARRAY_BASE_BYTES_LEFT, > where the base data memory may change to an array for the 2nd level > data memory for growing, likewise for shrinking. > > To make this part easier, we separate the base data memory and define > FLEX_ARRAY_BASE_SIZE as a same value of FLEX_ARRAY_PART_SIZE, as Neil > suggested. When new size is crossing the border, the base memory is > allocated as the array for the 2nd level data memory and its part[0] > is pointed to the old base memory, and do the opposite for shrinking. > > But it doesn't do any memory allocation or shrinking for elements in > flex_array_resize, as which should be done by flex_array_prealloc or > flex_array_shrink called by users. No memory leaks can be caused by > that. > > SCTP has benefited a lot from flex_array_resize() for managing its > stream memory so far. > > v1->v2: > Cc LKML and more developers. So I don't know what to do about this series. One of the responses stated that it has been proposed to remove flex_array and I don't know what to make of that, nor can I tell if that makes this series inappropriate or not.