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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,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 8010BC32771 for ; Wed, 22 Jan 2020 22:24:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4961D2465A for ; Wed, 22 Jan 2020 22:24:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728998AbgAVWYE (ORCPT ); Wed, 22 Jan 2020 17:24:04 -0500 Received: from kvm5.telegraphics.com.au ([98.124.60.144]:47750 "EHLO kvm5.telegraphics.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725911AbgAVWYD (ORCPT ); Wed, 22 Jan 2020 17:24:03 -0500 Received: by kvm5.telegraphics.com.au (Postfix, from userid 502) id 2974929988; Wed, 22 Jan 2020 17:23:59 -0500 (EST) To: "David S. Miller" Cc: Thomas Bogendoerfer , Chris Zankel , Laurent Vivier , Geert Uytterhoeven , Eric Dumazet , Stephen Hemminger , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Message-Id: <0c53b516bac19ca785b0a8e9ada7bcb6970fda5b.1579730846.git.fthain@telegraphics.com.au> In-Reply-To: References: From: Finn Thain Subject: [PATCH net v3 01/12] net/sonic: Add mutual exclusion for accessing shared state Date: Thu, 23 Jan 2020 09:07:26 +1100 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- Changed since v1: - Added spin lock, as requested by Geert. Changed since v2: - Added comment to explain the need for an irq lock. --- drivers/net/ethernet/natsemi/sonic.c | 49 ++++++++++++++++++++-------- drivers/net/ethernet/natsemi/sonic.h | 1 + 2 files changed, 36 insertions(+), 14 deletions(-) diff --git a/drivers/net/ethernet/natsemi/sonic.c b/drivers/net/ethernet/natsemi/sonic.c index b339125b2f09..8a7cff516281 100644 --- a/drivers/net/ethernet/natsemi/sonic.c +++ b/drivers/net/ethernet/natsemi/sonic.c @@ -64,6 +64,8 @@ static int sonic_open(struct net_device *dev) netif_dbg(lp, ifup, dev, "%s: initializing sonic driver\n", __func__); + spin_lock_init(&lp->lock); + for (i = 0; i < SONIC_NUM_RRS; i++) { struct sk_buff *skb = netdev_alloc_skb(dev, SONIC_RBSIZE + 2); if (skb == NULL) { @@ -206,8 +208,6 @@ static void sonic_tx_timeout(struct net_device *dev) * wake the tx queue * Concurrently with all of this, the SONIC is potentially writing to * the status flags of the TDs. - * Until some mutual exclusion is added, this code will not work with SMP. However, - * MIPS Jazz machines and m68k Macs were all uni-processor machines. */ static int sonic_send_packet(struct sk_buff *skb, struct net_device *dev) @@ -215,7 +215,8 @@ static int sonic_send_packet(struct sk_buff *skb, struct net_device *dev) struct sonic_local *lp = netdev_priv(dev); dma_addr_t laddr; int length; - int entry = lp->next_tx; + int entry; + unsigned long flags; netif_dbg(lp, tx_queued, dev, "%s: skb=%p\n", __func__, skb); @@ -237,6 +238,10 @@ static int sonic_send_packet(struct sk_buff *skb, struct net_device *dev) return NETDEV_TX_OK; } + spin_lock_irqsave(&lp->lock, flags); + + entry = lp->next_tx; + sonic_tda_put(dev, entry, SONIC_TD_STATUS, 0); /* clear status */ sonic_tda_put(dev, entry, SONIC_TD_FRAG_COUNT, 1); /* single fragment */ sonic_tda_put(dev, entry, SONIC_TD_PKTSIZE, length); /* length of packet */ @@ -246,10 +251,6 @@ static int sonic_send_packet(struct sk_buff *skb, struct net_device *dev) sonic_tda_put(dev, entry, SONIC_TD_LINK, sonic_tda_get(dev, entry, SONIC_TD_LINK) | SONIC_EOL); - /* - * Must set tx_skb[entry] only after clearing status, and - * before clearing EOL and before stopping queue - */ wmb(); lp->tx_len[entry] = length; lp->tx_laddr[entry] = laddr; @@ -272,6 +273,8 @@ static int sonic_send_packet(struct sk_buff *skb, struct net_device *dev) SONIC_WRITE(SONIC_CMD, SONIC_CR_TXP); + spin_unlock_irqrestore(&lp->lock, flags); + return NETDEV_TX_OK; } @@ -284,9 +287,21 @@ 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; + + /* The lock has two purposes. Firstly, it synchronizes sonic_interrupt() + * with sonic_send_packet() so that the two functions can share state. + * Secondly, it makes sonic_interrupt() re-entrant, as that is required + * by macsonic which must use two IRQs with different priority levels. + */ + spin_lock_irqsave(&lp->lock, flags); + + 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 +315,12 @@ 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 +422,12 @@ 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; } diff --git a/drivers/net/ethernet/natsemi/sonic.h b/drivers/net/ethernet/natsemi/sonic.h index 2b27f7049acb..f9506863e9d1 100644 --- a/drivers/net/ethernet/natsemi/sonic.h +++ b/drivers/net/ethernet/natsemi/sonic.h @@ -322,6 +322,7 @@ struct sonic_local { int msg_enable; struct device *device; /* generic device */ struct net_device_stats stats; + spinlock_t lock; }; #define TX_TIMEOUT (3 * HZ) -- 2.24.1