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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT 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 16BA3C282DA for ; Fri, 19 Apr 2019 19:13:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D2815204FD for ; Fri, 19 Apr 2019 19:12:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="iKNqEgMD" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729601AbfDSTM6 (ORCPT ); Fri, 19 Apr 2019 15:12:58 -0400 Received: from mail-wm1-f68.google.com ([209.85.128.68]:54602 "EHLO mail-wm1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726088AbfDSTM6 (ORCPT ); Fri, 19 Apr 2019 15:12:58 -0400 Received: by mail-wm1-f68.google.com with SMTP id c1so7128654wml.4 for ; Fri, 19 Apr 2019 12:12:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=es1iLl139MqIIzoVQVdVNHyENizy6SXrassvrh1IEwI=; b=iKNqEgMDx2SvsoTV74mwhZhYo0sszYqcp1d14TvGu+HDIhKsGeYJRFhMSBbDpv/zXz MKT9HcX9EAn9qI4RCBZv+nORLy/1W7/77k9RGE7I82EM2TE/EZQgYiKMffKkxlmfM1UM WZo8DOE4qlgbd9lxWY8XDMru9TdFx/dGmQoN+JjrAn9uWavvXEPWd9ZUkeurGqxx4EjW tNC+L2LjBP2AUACKFaVAvPwGXy0QnsTgpHzu44HYcU8CoUbR/cSO04qk7Bjwmlbji1h1 9ONheE2IzenBZm5L1nNfsZlPlx1OeZJ0H87K01xpocbSvSIRv5/K6cBEtWBJnMeeeDZ6 /Mug== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=es1iLl139MqIIzoVQVdVNHyENizy6SXrassvrh1IEwI=; b=Iq/a/9mcwWRBJ7SKfE1MwXnqLEywyQEuH65mk/fBv44Lr1krGF+T7eGK7uAJ2p0im6 eJ9OhODr64sN/kVtJihlANBdQoUz8zM5qXmtsaF69V+7kt/p7Ey9DGwZEYCXmVvh8qkT tiQ6hOLGM6//gsUXn+eVio+OerWVIObnXNc/3Lgsr0zEZoH8bllQMMRAtkqdRpkkRJ6M YYOmPG6DgAN7ZdfVIDAPTA3egHg2LDdMoU91rEZeA5326tNsqgXC5lWXi4mecj5htx3G vJoUpYwUzF0i2YRB4A8jbyajzJt8hpXWYtxEJj7DKL3sYFwey1BGoW0KqAUSTtj/kDOZ Y19A== X-Gm-Message-State: APjAAAX/qp9ZNYUO7mOZDaDZt/LtOJGWR0J6g/tBBGv1KrFPmnTA3ldw qfERkNT7XGOaid5xkmOSeGGgANxaCHc= X-Google-Smtp-Source: APXvYqyxnX7B2gQanmwA6RUDY5jBFce9H2LGwab2QkWaHpOGfs6Eg7RNQNbrGj6B19LxNM+9PaE97g== X-Received: by 2002:a1c:e709:: with SMTP id e9mr1819419wmh.14.1555662720183; Fri, 19 Apr 2019 01:32:00 -0700 (PDT) Received: from apalos (athedsl-4485328.home.otenet.gr. [94.71.60.216]) by smtp.gmail.com with ESMTPSA id h12sm1046285wrw.36.2019.04.19.01.31.58 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 19 Apr 2019 01:31:59 -0700 (PDT) Date: Fri, 19 Apr 2019 11:31:56 +0300 From: Ilias Apalodimas To: Ivan Khoronzhuk Cc: grygorii.strashko@ti.com, linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, hawk@kernel.org, xdp-newbies@vger.kernel.org, ast@kernel.org, aniel@iogearbox.net, jakub.kicinski@netronome.com, john.fastabend@gmail.com Subject: Re: [RFC PATCH 3/3] net: ethernet: ti: cpsw: add XDP support Message-ID: <20190419083156.GA6687@apalos> References: <20190417174942.11811-1-ivan.khoronzhuk@linaro.org> <20190417174942.11811-4-ivan.khoronzhuk@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190417174942.11811-4-ivan.khoronzhuk@linaro.org> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Ivan, > +static struct page *cpsw_alloc_page(struct cpsw_common *cpsw) > +{ > + struct page_pool *pool = cpsw->rx_page_pool; > + struct page *page; > + int i = 0; > + > + do { > + page = page_pool_dev_alloc_pages(pool); > + if (!page) > + return NULL; > + > + /* skip pages used by skb netstack */ I think the comment here is wrong and might confuse people. The page ref cnt is 1, which means the packet was *processed* and netstack is done with it, hence you can re-use it. If it's !=1 then you correctly unmap the buffer and decrease the ref cnt, so it will eventually be freed and not returned to the pool, right? > + if (page_ref_count(page) == 1) > + break; > + > + /* it's a pitty, but free page */ > + page_pool_recycle_direct(pool, page); > + } while (++i < descs_pool_size); > + > + return page; > +} > + /Ilias