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 23:28:30 +0300 Message-ID: <20190702202829.GI4510@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> <20190702185839.GH4510@khorivan> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Return-path: Content-Disposition: inline In-Reply-To: <20190702185839.GH4510@khorivan> Sender: linux-kernel-owner@vger.kernel.org To: Jesper Dangaard Brouer , 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 09:58:40PM +0300, Ivan Khoronzhuk wrote: >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. I can pick up this one but remove description related to (2) and add appropriate modifications to cpsw. -- Regards, Ivan Khoronzhuk