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=-7.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 C58DCC43219 for ; Sat, 4 May 2019 02:07:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8DC0220449 for ; Sat, 4 May 2019 02:07:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="NpnaNJZ+" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726912AbfEDCHm (ORCPT ); Fri, 3 May 2019 22:07:42 -0400 Received: from mail-pg1-f193.google.com ([209.85.215.193]:38421 "EHLO mail-pg1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726059AbfEDCHl (ORCPT ); Fri, 3 May 2019 22:07:41 -0400 Received: by mail-pg1-f193.google.com with SMTP id j26so3590341pgl.5; Fri, 03 May 2019 19:07:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:openpgp:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=38+4eU8WgqZwPRPwmTdRt5lD2lmx6xd+gWZh4oao4Mw=; b=NpnaNJZ+ZjJBwtiAZryBHs3e5jDy7zGcBHZNsCYK5RUApK29m9vLtrWBewlgKRYQBp 2z2TmqR9thnzJBgPKE0xnCz03VViGry9MLrGsYyWaCk/Tulx09Jv2VME2t/6pzMo3OIN iY6YfIH24iASLB7GoZQrMKO7eSp0onbEs5HGvPgWgsaZ9/bv3UHxdRXxFV0vvK/rMYjz mby8dnZbnxtjiO/a1vDDgQanXI/8EJHOoIkwVbzD+D6jPu/loGMuQ9Qc5H2Qz3MmLDWJ sU/evkNPzUb7e1JpBKjLS6O8AgmlDBqKKL+lWpT9FQuefDNvkr3DGEnNHArIh26qF5Dh L0gQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:openpgp:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=38+4eU8WgqZwPRPwmTdRt5lD2lmx6xd+gWZh4oao4Mw=; b=pCCIolnELmjvn+9uYqxMFBpg7rrNe1+Z4H3J+VeYLJ4bjcTDS2obhj+E+nXPvslQb7 dMFzCQOJZjG+uT88f3dYVM0//RbiGn5R/CWgrSKEEtQ5C8LZJ0YQY1ix/ZrUoCA/YUBs qW6jk0c5HDQYjdBASsbl/1VGx/hogyELX0kP+vGSxMhJBgJTgAit02pOJtJfOo1HBscY v735NUTIbhuPtSC83qKAB5ta57uUrHoWaWX8Cfe1L0VyTRVrK85x/2iQN2EItAZlZrVi DXxVXo5FX3SiHr37ADCZKRTf43qZq5opvzvijTPmZjTDBxzyhX+gi78bTnqSwfQf3GVo JRQw== X-Gm-Message-State: APjAAAXrVMkcSDutumOsBcMrGMgrFYvjtfr5C9e9yCzNMPW/Q9AAfNv7 G4jUk7O/ZPXWL8ZflYjDIIKzQ00C X-Google-Smtp-Source: APXvYqyVijvW2WSBxF0LRYWIF0AVfL4T8/oWXKh2ztmFogrmIfKHZ3bGGHSOslw/AjcRPAF8lOpVng== X-Received: by 2002:a63:4a5a:: with SMTP id j26mr14329988pgl.361.1556935660616; Fri, 03 May 2019 19:07:40 -0700 (PDT) Received: from [10.230.28.107] ([192.19.223.250]) by smtp.gmail.com with ESMTPSA id f15sm3976351pgf.18.2019.05.03.19.07.38 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 03 May 2019 19:07:39 -0700 (PDT) Subject: Re: [PATCH net-next 5/9] net: dsa: Add support for deferred xmit To: Vladimir Oltean , vivien.didelot@gmail.com, andrew@lunn.ch, davem@davemloft.net Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20190504011826.30477-1-olteanv@gmail.com> <20190504011826.30477-6-olteanv@gmail.com> From: Florian Fainelli Openpgp: preference=signencrypt Message-ID: <3232ef43-d568-0851-4511-6fe7c86d9e8a@gmail.com> Date: Fri, 3 May 2019 19:07:37 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190504011826.30477-6-olteanv@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/3/2019 6:18 PM, Vladimir Oltean wrote: > Some hardware needs to take some convincing work in order to receive > frames on the CPU port (such as the sja1105 which takes temporary L2 > forwarding rules over SPI that last for a single frame). Such work needs > a sleepable context, and because the regular .ndo_start_xmit is atomic, > this cannot be done in the tagger. So introduce a generic DSA mechanism > that sets up a transmit skb queue and a workqueue for deferred > transmission. > > The new driver callback (.port_deferred_xmit) is in dsa_switch and not > in the tagger because the operations that require sleeping typically > also involve interacting with the hardware, and not simply skb > manipulations. Therefore having it there simplifies the structure a bit > and makes it unnecessary to export functions from the driver to the > tagger. > > The driver is responsible of calling dsa_enqueue_skb which transfers it > to the master netdevice. This is so that it has a chance of performing > some more work afterwards, such as cleanup or TX timestamping. > > To tell DSA that skb xmit deferral is required, I have thought about > changing the return type of the tagger .xmit from struct sk_buff * into > a enum dsa_tx_t that could potentially encode a DSA_XMIT_DEFER value. > > But the trailer tagger is reallocating every skb on xmit and therefore > making a valid use of the pointer return value. So instead of reworking > the API in complicated ways, right now a boolean property in the newly > introduced DSA_SKB_CB is set. > > Signed-off-by: Vladimir Oltean > --- [snip] > static inline struct dsa_port *dsa_slave_to_port(const struct net_device *dev) > { > struct dsa_slave_priv *p = netdev_priv(dev); > diff --git a/net/dsa/slave.c b/net/dsa/slave.c > index 8ad9bf957da1..cfb8cba6458c 100644 > --- a/net/dsa/slave.c > +++ b/net/dsa/slave.c > @@ -120,6 +120,9 @@ static int dsa_slave_close(struct net_device *dev) > struct net_device *master = dsa_slave_to_master(dev); > struct dsa_port *dp = dsa_slave_to_port(dev); > > + cancel_work_sync(&dp->xmit_work); > + skb_queue_purge(&dp->xmit_queue); > + > phylink_stop(dp->pl); Don't you also need to do that for dsa_slave_suspend() in case the xmit() raced with netif_device_detach() somehow? -- Florian