From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ivan Khoronzhuk Subject: Re: [PATCH] net: core: page_pool: add user refcnt and reintroduce page_pool_destroy Date: Tue, 2 Jul 2019 21:58:40 +0300 Message-ID: <20190702185839.GH4510@khorivan> References: <20190702153902.0e42b0b2@carbon> <156207778364.29180.5111562317930943530.stgit@firesoul> <20190702144426.GD4510@khorivan> <20190702165230.6caa36e3@carbon> <20190702145612.GF4510@khorivan> <20190702171029.76c60538@carbon> <20190702152112.GG4510@khorivan> <20190702202907.15fb30ce@carbon> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Return-path: Content-Disposition: inline In-Reply-To: <20190702202907.15fb30ce@carbon> Sender: linux-kernel-owner@vger.kernel.org To: Jesper Dangaard Brouer Cc: netdev@vger.kernel.org, Ilias Apalodimas , grygorii.strashko@ti.com, jakub.kicinski@netronome.com, daniel@iogearbox.net, john.fastabend@gmail.com, ast@kernel.org, linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org List-Id: linux-omap@vger.kernel.org On Tue, Jul 02, 2019 at 08:29:07PM +0200, Jesper Dangaard Brouer wrote: >On Tue, 2 Jul 2019 18:21:13 +0300 >Ivan Khoronzhuk wrote: > >> On Tue, Jul 02, 2019 at 05:10:29PM +0200, Jesper Dangaard Brouer wrote: >> >On Tue, 2 Jul 2019 17:56:13 +0300 >> >Ivan Khoronzhuk wrote: >> > >> >> On Tue, Jul 02, 2019 at 04:52:30PM +0200, Jesper Dangaard Brouer wrote: >> >> >On Tue, 2 Jul 2019 17:44:27 +0300 >> >> >Ivan Khoronzhuk wrote: >> >> > >> >> >> On Tue, Jul 02, 2019 at 04:31:39PM +0200, Jesper Dangaard Brouer wrote: >> >> >> >From: Ivan Khoronzhuk >> >> >> > >> >> >> >Jesper recently removed page_pool_destroy() (from driver invocation) and >> >> >> >moved shutdown and free of page_pool into xdp_rxq_info_unreg(), in-order to >> >> >> >handle in-flight packets/pages. This created an asymmetry in drivers >> >> >> >create/destroy pairs. >> >> >> > >> >> >> >This patch add page_pool user refcnt and reintroduce page_pool_destroy. >> >> >> >This serves two purposes, (1) simplify drivers error handling as driver now >> >> >> >drivers always calls page_pool_destroy() and don't need to track if >> >> >> >xdp_rxq_info_reg_mem_model() was unsuccessful. (2) allow special cases >> >> >> >where a single RX-queue (with a single page_pool) provides packets for two >> >> >> >net_device'es, and thus needs to register the same page_pool twice with two >> >> >> >xdp_rxq_info structures. >> >> >> >> >> >> As I tend to use xdp level patch there is no more reason to mention (2) case >> >> >> here. XDP patch serves it better and can prevent not only obj deletion but also >> >> >> pool flush, so, this one patch I could better leave only for (1) case. >> >> > >> >> >I don't understand what you are saying. >> >> > >> >> >Do you approve this patch, or do you reject this patch? >> >> > >> >> It's not reject, it's proposition to use both, XDP and page pool patches, >> >> each having its goal. >> > >> >Just to be clear, if you want this patch to get accepted you have to >> >reply with your Signed-off-by (as I wrote). >> > >> >Maybe we should discuss it in another thread, about why you want two >> >solutions to the same problem. >> >> If it solves same problem I propose to reject this one and use this: >> https://lkml.org/lkml/2019/7/2/651 > >No, I propose using this one, and rejecting the other one. There is at least several arguments against this one (related (2) purpose) It allows: - avoid changes to page_pool/mlx5/netsec - save not only allocator obj but allocator "page/buffer flush" - buffer flush can be present not only in page_pool but for other allocators that can behave differently and not so simple solution. - to not limit cpsw/(potentially others) to use "page_pool" allocator only .... This patch better leave also, as it simplifies error path for page_pool and have more error prone usage comparing with existent one. Please, don't limit cpsw and potentially other drivers to use only page_pool it can be zca or etc... I don't won't to modify each allocator. I propose to add both as by fact they solve different problems with common solution. -- Regards, Ivan Khoronzhuk