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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 86550C433EF for ; Mon, 18 Oct 2021 11:36:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6EA0B61077 for ; Mon, 18 Oct 2021 11:36:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231220AbhJRLil (ORCPT ); Mon, 18 Oct 2021 07:38:41 -0400 Received: from mail.kernel.org ([198.145.29.99]:43152 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230346AbhJRLil (ORCPT ); Mon, 18 Oct 2021 07:38:41 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id AF6DE60E76; Mon, 18 Oct 2021 11:36:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1634556990; bh=z6AydGC4A6ArPdvqzYVHmE38LAxTFQx6eEXB/CS+6gY=; h=Subject:To:Cc:From:Date:From; b=f8kP509rP1Eph4khnmuE33UtiakHi+HryAX92W8JOos2RYokMl0FO+1LVv5Oo9G0O 7f23enI9UheEn84ogtuq8xGdl+FlVrnc4NYesFnsY0vEBhDp6RMlXgbeXsq/Udr37h l7DPoQ4Q6NffpeLoNIu8TaKJncL2J+K2GDZxRZ7k= Subject: FAILED: patch "[PATCH] net: dsa: felix: purge skb from TX timestamping queue if it" failed to apply to 5.14-stable tree To: vladimir.oltean@nxp.com, kuba@kernel.org Cc: From: Date: Mon, 18 Oct 2021 13:36:27 +0200 Message-ID: <1634556987377@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 5.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 1328a883258b4507909090ed0a9ad63771f9f780 Mon Sep 17 00:00:00 2001 From: Vladimir Oltean Date: Tue, 12 Oct 2021 14:40:42 +0300 Subject: [PATCH] net: dsa: felix: purge skb from TX timestamping queue if it cannot be sent At present, when a PTP packet which requires TX timestamping gets dropped under congestion by the switch, things go downhill very fast. The driver keeps a clone of that skb in a queue of packets awaiting TX timestamp interrupts, but interrupts will never be raised for the dropped packets. Moreover, matching timestamped packets to timestamps is done by a 2-bit timestamp ID, and this can wrap around and we can match on the wrong skb. Since with the default NPI-based tagging protocol, we get no notification about packet drops, the best we can do is eventually recover from the drop of a PTP frame: its skb will be dead memory until another skb which was assigned the same timestamp ID happens to find it. However, with the ocelot-8021q tagger which injects packets using the manual register interface, it appears that we can check for more information, such as: - whether the input queue has reached the high watermark or not - whether the injection group's FIFO can accept additional data or not so we know that a PTP frame is likely to get dropped before actually sending it, and drop it ourselves (because DSA uses NETIF_F_LLTX, so it can't return NETDEV_TX_BUSY to ask the qdisc to requeue the packet). But when we do that, we can also remove the skb from the timestamping queue, because there surely won't be any timestamp that matches it. Fixes: 0a6f17c6ae21 ("net: dsa: tag_ocelot_8021q: add support for PTP timestamping") Signed-off-by: Vladimir Oltean Signed-off-by: Jakub Kicinski diff --git a/drivers/net/dsa/ocelot/felix.c b/drivers/net/dsa/ocelot/felix.c index f8603e068e7c..9af8f900aa56 100644 --- a/drivers/net/dsa/ocelot/felix.c +++ b/drivers/net/dsa/ocelot/felix.c @@ -1074,6 +1074,33 @@ static int felix_init_structs(struct felix *felix, int num_phys_ports) return 0; } +static void ocelot_port_purge_txtstamp_skb(struct ocelot *ocelot, int port, + struct sk_buff *skb) +{ + struct ocelot_port *ocelot_port = ocelot->ports[port]; + struct sk_buff *clone = OCELOT_SKB_CB(skb)->clone; + struct sk_buff *skb_match = NULL, *skb_tmp; + unsigned long flags; + + if (!clone) + return; + + spin_lock_irqsave(&ocelot_port->tx_skbs.lock, flags); + + skb_queue_walk_safe(&ocelot_port->tx_skbs, skb, skb_tmp) { + if (skb != clone) + continue; + __skb_unlink(skb, &ocelot_port->tx_skbs); + skb_match = skb; + break; + } + + spin_unlock_irqrestore(&ocelot_port->tx_skbs.lock, flags); + + WARN_ONCE(!skb_match, + "Could not find skb clone in TX timestamping list\n"); +} + #define work_to_xmit_work(w) \ container_of((w), struct felix_deferred_xmit_work, work) @@ -1097,6 +1124,7 @@ static void felix_port_deferred_xmit(struct kthread_work *work) if (!retries) { dev_err(ocelot->dev, "port %d failed to inject skb\n", port); + ocelot_port_purge_txtstamp_skb(ocelot, port, skb); kfree_skb(skb); return; }