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=-5.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 B7CEEC33CAF for ; Tue, 21 Jan 2020 22:19:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8D154217F4 for ; Tue, 21 Jan 2020 22:19:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="V6+0gFQx" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729130AbgAUWT4 (ORCPT ); Tue, 21 Jan 2020 17:19:56 -0500 Received: from mail-pg1-f195.google.com ([209.85.215.195]:34436 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727847AbgAUWTz (ORCPT ); Tue, 21 Jan 2020 17:19:55 -0500 Received: by mail-pg1-f195.google.com with SMTP id r11so2292446pgf.1; Tue, 21 Jan 2020 14:19:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=87q9xhoPKVsZRpT7sXkkO2m2/qUarjs1kR3PGeTcCa8=; b=V6+0gFQxv4KVdfOevLuORPsMA0IRumBkHZGOYQyPErMao8SthHHq7cBPYxHBMZjQGI TNZuiJNT4SeYK8K0hdMIqq7jJSaF40Tp7OuUfxFOqlBI+iSSJX63CpbOZS0BcUeIGeoA iVRvlfpR6KCTMSGOZyFpbivijF8HsnSHpmRCRG2298dfJEJmdXkeWIZl4Mz6IMyuebYc 5KqCSCfsCnmhYTj4RyLanptRRVWnLmbu/hd3dMZYbxEFVWfms6NurkIlCs2oanVYqAHO Viop3Ydl33vbMniGsD8HecJnNHKeAxPqa1Nmu3bZGcKMAQRrsEP/LsWkBH6TrqNOqSjv G0sQ== 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:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=87q9xhoPKVsZRpT7sXkkO2m2/qUarjs1kR3PGeTcCa8=; b=hgHab1ttOOuH3FRnCuCAJ1glqxLk4HVJbU827Yy2+GEwzU+qyhX+wNNk25yRxnHbtk cYcHWXNuG8ICDHXRet/rhAEnd5kauhkzJj8b9TDxJaBafpEezRgYjd/tWOGCCc75tWGz CsffxYnFmia1dfBiFPxKGPl+9Ea1zfNwfaVzaV02A+aHHNV07S60iheOSVUMZq1brKmg /FfFnRsi+v4NSqgdgQzEPd0XelKRj1V48bcUu0UxbiK7QrqwSittxuLMAIR8eD8y1RRv vNt7sP9HmPFkc9c8w+OPvmEAUVWlTecShiDlYGgYICb2KdU5aHYqfApx3xrFi+nYIY6+ hMnA== X-Gm-Message-State: APjAAAU4nxyPF86fhkO/YFJnq0hPuUhnAKpKkn4MdiVd9+8o1QhfIw5q zbZ/6XwfzT7eo7tOur6lZgJHQRmU X-Google-Smtp-Source: APXvYqzX+G5EAYzlbOeRoettvDYSWW16bHWnmdXsnq9AUn5obiFNsulAcXmnW6RhQSNdd6qnIwIbQQ== X-Received: by 2002:a62:5447:: with SMTP id i68mr6697130pfb.44.1579645194049; Tue, 21 Jan 2020 14:19:54 -0800 (PST) Received: from ?IPv6:2620:15c:2c1:200:55c7:81e6:c7d8:94b? ([2620:15c:2c1:200:55c7:81e6:c7d8:94b]) by smtp.gmail.com with ESMTPSA id a1sm43969982pfo.68.2020.01.21.14.19.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 21 Jan 2020 14:19:53 -0800 (PST) Subject: Re: [PATCH net v2 01/12] net/sonic: Add mutual exclusion for accessing shared state To: Finn Thain , "David S. Miller" Cc: Thomas Bogendoerfer , Chris Zankel , Laurent Vivier , Geert Uytterhoeven , netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: From: Eric Dumazet Message-ID: <0113c00f-3f77-8324-95a8-31dd6f64fa6a@gmail.com> Date: Tue, 21 Jan 2020 14:19:51 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: 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 1/21/20 1:22 PM, Finn Thain wrote: > The netif_stop_queue() call in sonic_send_packet() races with the > netif_wake_queue() call in sonic_interrupt(). This causes issues > like "NETDEV WATCHDOG: eth0 (macsonic): transmit queue 0 timed out". > Fix this by disabling interrupts when accessing tx_skb[] and next_tx. > Update a comment to clarify the synchronization properties. > > Fixes: efcce839360f ("[PATCH] macsonic/jazzsonic network drivers update") > Tested-by: Stan Johnson > Signed-off-by: Finn Thain > @@ -284,9 +287,16 @@ static irqreturn_t sonic_interrupt(int irq, void *dev_id) > struct net_device *dev = dev_id; > struct sonic_local *lp = netdev_priv(dev); > int status; > + unsigned long flags; > + > + spin_lock_irqsave(&lp->lock, flags); This is a hard irq handler, no need to block hard irqs. spin_lock() here is enough. > + > + status = SONIC_READ(SONIC_ISR) & SONIC_IMR_DEFAULT; > + if (!status) { > + spin_unlock_irqrestore(&lp->lock, flags); > > - if (!(status = SONIC_READ(SONIC_ISR) & SONIC_IMR_DEFAULT)) > return IRQ_NONE; > + } > > do { > if (status & SONIC_INT_PKTRX) { > @@ -300,11 +310,12 @@ static irqreturn_t sonic_interrupt(int irq, void *dev_id) > int td_status; > int freed_some = 0; > > - /* At this point, cur_tx is the index of a TD that is one of: > - * unallocated/freed (status set & tx_skb[entry] clear) > - * allocated and sent (status set & tx_skb[entry] set ) > - * allocated and not yet sent (status clear & tx_skb[entry] set ) > - * still being allocated by sonic_send_packet (status clear & tx_skb[entry] clear) > + /* The state of a Transmit Descriptor may be inferred > + * from { tx_skb[entry], td_status } as follows. > + * { clear, clear } => the TD has never been used > + * { set, clear } => the TD was handed to SONIC > + * { set, set } => the TD was handed back > + * { clear, set } => the TD is available for re-use > */ > > netif_dbg(lp, intr, dev, "%s: tx done\n", __func__); > @@ -406,7 +417,12 @@ static irqreturn_t sonic_interrupt(int irq, void *dev_id) > /* load CAM done */ > if (status & SONIC_INT_LCD) > SONIC_WRITE(SONIC_ISR, SONIC_INT_LCD); /* clear the interrupt */ > - } while((status = SONIC_READ(SONIC_ISR) & SONIC_IMR_DEFAULT)); > + > + status = SONIC_READ(SONIC_ISR) & SONIC_IMR_DEFAULT; > + } while (status); > + > + spin_unlock_irqrestore(&lp->lock, flags); > + > return IRQ_HANDLED;