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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 BFEA8C433EF for ; Fri, 24 Sep 2021 08:04:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A6F1360F48 for ; Fri, 24 Sep 2021 08:04:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244528AbhIXIFi (ORCPT ); Fri, 24 Sep 2021 04:05:38 -0400 Received: from szxga08-in.huawei.com ([45.249.212.255]:16235 "EHLO szxga08-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244543AbhIXIEY (ORCPT ); Fri, 24 Sep 2021 04:04:24 -0400 Received: from dggemv704-chm.china.huawei.com (unknown [172.30.72.56]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4HG4G917Dcz1DH3m; Fri, 24 Sep 2021 16:00:33 +0800 (CST) Received: from dggpemm500005.china.huawei.com (7.185.36.74) by dggemv704-chm.china.huawei.com (10.3.19.47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.8; Fri, 24 Sep 2021 16:01:45 +0800 Received: from [10.69.30.204] (10.69.30.204) by dggpemm500005.china.huawei.com (7.185.36.74) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2308.8; Fri, 24 Sep 2021 16:01:45 +0800 Subject: Re: [PATCH net-next 1/7] page_pool: disable dma mapping support for 32-bit arch with 64-bit DMA To: Ilias Apalodimas CC: Jesper Dangaard Brouer , "David S. Miller" , Jakub Kicinski , "Jesper Dangaard Brouer" , Networking , open list , , "Jesper Dangaard Brouer" , Jonathan Lemon , Alexander Lobakin , Willem de Bruijn , Cong Wang , Paolo Abeni , "Kevin Hao" , Aleksandr Nogikh , Marco Elver , , Eric Dumazet , Alexander Duyck , David Ahern References: <20210922094131.15625-1-linyunsheng@huawei.com> <20210922094131.15625-2-linyunsheng@huawei.com> <0ffa15a1-742d-a05d-3ea6-04ff25be6a29@redhat.com> <27bc803a-1687-a583-fa6b-3691fef7552e@huawei.com> From: Yunsheng Lin Message-ID: <001c1518-b5db-c1e3-0feb-657ecde61cdc@huawei.com> Date: Fri, 24 Sep 2021 16:01:44 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.69.30.204] X-ClientProxiedBy: dggeme718-chm.china.huawei.com (10.1.199.114) To dggpemm500005.china.huawei.com (7.185.36.74) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/9/24 15:25, Ilias Apalodimas wrote: > On Fri, 24 Sept 2021 at 10:04, Yunsheng Lin wrote: >> >> On 2021/9/23 21:07, Ilias Apalodimas wrote: >>> On Thu, Sep 23, 2021 at 07:13:11PM +0800, Yunsheng Lin wrote: >>>> On 2021/9/23 18:02, Ilias Apalodimas wrote: >>>>> Hi Jesper, >>>>> >>>>> On Thu, 23 Sept 2021 at 12:33, Jesper Dangaard Brouer >>>>> wrote: >>>>>> >>>>>> >>>>>> On 22/09/2021 11.41, Yunsheng Lin wrote: >>>>>>> diff --git a/net/core/page_pool.c b/net/core/page_pool.c >>>>>>> index 1a6978427d6c..a65bd7972e37 100644 >>>>>>> --- a/net/core/page_pool.c >>>>>>> +++ b/net/core/page_pool.c >>>>>>> @@ -49,6 +49,12 @@ static int page_pool_init(struct page_pool *pool, >>>>>>> * which is the XDP_TX use-case. >>>>>>> */ >>>>>>> if (pool->p.flags & PP_FLAG_DMA_MAP) { >>>>>>> + /* DMA-mapping is not supported on 32-bit systems with >>>>>>> + * 64-bit DMA mapping. >>>>>>> + */ >>>>>>> + if (sizeof(dma_addr_t) > sizeof(unsigned long)) >>>>>>> + return -EINVAL; >>>>>> >>>>>> As I said before, can we please use another error than EINVAL. >>>>>> We should give drivers a chance/ability to detect this error, and e.g. >>>>>> fallback to doing DMA mappings inside driver instead. >>>>>> >>>>>> I suggest using EOPNOTSUPP 95 (Operation not supported). >>>> >>>> Will change it to EOPNOTSUPP, thanks. >>> >>> Mind sending this one separately (and you can keep my reviewed-by). It >>> fits nicely on it's own and since I am not sure about the rest of the >>> changes yet, it would be nice to get this one in. >> >> I am not sure sending this one separately really makes sense, as it is >> mainly used to make supporting the "keep track of pp page when __skb_frag_ref() >> is called" in patch 5 easier. > > It rips out support for devices that are 32bit and have 64bit dma and > make the whole code easier to follow. I thought we agreed on removing > the support for those devices regardless didn't we? I am actually not convinced that the code about PAGE_POOL_DMA_USE_PP_FRAG_COUNT (maybe the name is somewhat confusiong) as it it now, but it is after adding patch 5, and it seems we are not handing the skb_split() case in tso_fragment() for 32bit arch with 64bit dma too if we still keep PAGE_POOL_DMA_USE_PP_FRAG_COUNT macro. > > Regards > /Ilias > . >