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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=no 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 1941FC33CAA for ; Tue, 21 Jan 2020 23:34:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E3C0124125 for ; Tue, 21 Jan 2020 23:34:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728913AbgAUXeB (ORCPT ); Tue, 21 Jan 2020 18:34:01 -0500 Received: from kvm5.telegraphics.com.au ([98.124.60.144]:46418 "EHLO kvm5.telegraphics.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725933AbgAUXeA (ORCPT ); Tue, 21 Jan 2020 18:34:00 -0500 Received: from localhost (localhost.localdomain [127.0.0.1]) by kvm5.telegraphics.com.au (Postfix) with ESMTP id 9E474272D8; Tue, 21 Jan 2020 18:33:54 -0500 (EST) Date: Wed, 22 Jan 2020 10:33:53 +1100 (AEDT) From: Finn Thain To: Eric Dumazet cc: "David S. Miller" , Thomas Bogendoerfer , Chris Zankel , Laurent Vivier , Geert Uytterhoeven , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net v2 01/12] net/sonic: Add mutual exclusion for accessing shared state In-Reply-To: <0113c00f-3f77-8324-95a8-31dd6f64fa6a@gmail.com> Message-ID: References: <0113c00f-3f77-8324-95a8-31dd6f64fa6a@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, 21 Jan 2020, Eric Dumazet wrote: > 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. > Well, yes, assuming we're dealing with SMP [1]. Probably just disabling pre-emption is all that will ever be needed. Anyway, the real problem solved by disabling irqs is that macsonic must avoid re-entrance of sonic_interrupt(). [2] [1] https://lore.kernel.org/netdev/alpine.LNX.2.21.1.2001211026190.8@nippy.intranet/T/#m0523c8b2a26a410ed56889d9230c37ba1160d40a [2] https://lore.kernel.org/netdev/alpine.LNX.2.21.1.2001211026190.8@nippy.intranet/T/#m1c8ca580d2b45e61a628d17839978d0bd5aaf061